Precision Digital PD6938-EX, PD6938-HA, PD6938 User guide

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

PRECISION DIGITAL CORPORATION

233 South Street • Hopkinton MA 01748 USA
Tel [phone] • [phone]

www.predig.com

• Fully-Approved Explosion-Proof & Intrinsically Safe Pulse Input Flow Rate/Totalizers

• NPN Open Collector, PNP, TTL, Switch Contact,

Sine Wave (Magnetic Pickup Coil), or Active Square Wave Inputs

• Top Display: Five 12-Segment Alphanumeric Characters, 0.7" (17.8 mm)

• Bottom Display: Eight 14-Segment Alphanumeric Characters, 0.4" (10.2 mm)

• Display Mountable at 0°, 90°, 180°, & 270° (No Tools Required)

• CapTouch Through-Glass Button Programming with Normal and Delayed Modes

• Red Backlight for Alarm Conditions, Enable and Disable Backlight from Menu

• 8-Digit Total & Grand Total Display, Up to 13 Digits Using Both Lines

• Display Rate & Total Simultaneously

• Bi-Directional Flow Detection Via Digital Input

• Non-Resettable Grand Total

• Display Previous Total and Previous Grand Total with Time-of-Day Reset Feature

• Reset Total / Grand Total with CapTouch Button, Digital Input, or Time-of-Day Feature

• Automatic or Manual Batch Control

• K-Factor Calibration or Scaling with Up to 32-Point Linearization

• Gate Function for Rate Display of Slow Pulse Rates

• (2) Open Collector Outputs Standard; Assignable to Pulse, Alarm, Timer, or Stopwatch

• (2) Optional Solid-State Relays; Assignable to Alarm, Sample, Timer, Batch Control, or Stopwatch

• Optional Isolated 4-20 mA Analog Output

• Free PC-Based MeterView XL USB Programming Software

• 9-30 VDC, Battery, or 4-20 mA Output Power Options

• Battery-Powered Momentary Backlight & Display Sleep and Off Modes to Extend Battery Life

• Modbus RTU RS-485 Communications Standard on DC & Battery Powered Models

• On-Board Data Logging of up to 2,032 Records and Modbus® Accessible Data

• Password Protection for Settings, Total & Grand Total

• CSA Certified for Explosion-Proof / Dust-Ignition Proof / Flame-Proof

• ATEX and IECEx Certified as Intrinsically Safe and Explosion-Proof

• Operating Temp Range: -40 to 75°C (-40 to 167°F)

• Installation Temp Range: -55 to 75°C (-67 to 167°F)

• Conformal Coated PCBs for Dust & Humidity Protection

• Flange for Wall or Pipe Mounting; Loop for Stainless Steel Tag; Holes for Tamper-Proof Seal

• Explosion-Proof Aluminum & Stainless Steel Enclosures with 1", 3/4", or M20 Connections

• 3-Year Warranty

IECEx

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

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The Complete PD6900 Series

Plastic Enclosures - General Purpose

PD6907-GP-PL

4-20 mA Input

Feet & Inches Meter

PD6908-GP-PL

4-20 mA Input

Process Meter

PD6928-GP-PL

4-20 mA Input

Flow Rate/Totalizer

PD6938-GP-PL

Pulse Input

Flow Rate/Totalizer

Aluminum Enclosures - Hazardous Area Approved

PD6907-HA-AL

4-20 mA Input

Feet & Inches Meter

PD6908-HA-AL

4-20 mA Input

Process Meter

PD6928-HA-AL

4-20 mA Input

Flow Rate/Totalizer

PD6938-XX-AL

Pulse Input

Flow Rate/Totalizer

Stainless Steel Enclosures - Hazardous Area Approved

PD6907-HA-SS

4-20 mA Input

Feet & Inches Meter

PD6908-HA-SS

4-20 mA Input

Process Meter

PD6928-HA-SS

4-20 mA Input

Flow Rate/Totalizer

PD6938-XX-SS

Pulse Input

Flow Rate/Totalizer

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

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Table of Contents

Introduction .......................................................................................................... 6

Key Features ........................................................................................................ 7

Ordering Information ......................................................................................... 13

-HA Models (Dual Hazardous Approved) .................................................... 13

-IS Models (Intrinsically Safe Approved) ..................................................... 14

-EX Models (Explosion-Proof Approved) .................................................... 15

Accessories ................................................................................................... 17

Specifications..................................................................................................... 19

Display ............................................................................................................ 19

General ........................................................................................................... 19

Battery ............................................................................................................ 20

-IS Models (Options: P & R) 3xAA-Cell ....................................................... 20

-EX Models (Options: A & M) A-Size........................................................... 20

-EX Models (Options: B & N) C-Size ........................................................... 20

Battery Life with Modbus Continuously On ................................................. 20

Enclosure ....................................................................................................... 20

Pulse Input ..................................................................................................... 21

Rate/Totalizer ................................................................................................. 21

Batch Control ................................................................................................. 21

Common Open Collector & Relay Specifications ....................................... 22

Open Collector Outputs ................................................................................ 22

Solid-State Relays ......................................................................................... 22

4-20 mA Transmitter Output ......................................................................... 22

On-Board Digital Input .................................................................................. 22

Serial Communications ................................................................................. 23

MeterView XL Software ................................................................................. 23

General Compliance Information ..................................................................... 23

Electromagnetic Compatibility ..................................................................... 23

Hazardous Area Approvals ............................................................................... 24

-HA Models (Dual Hazardous Approved) .................................................... 24

-IS Models (Intrinsically Safe Approved) ..................................................... 24

-EX Models (Explosion-Proof Approved)..................................................... 24

EU Declaration of Conformity ........................................................................... 26

Safety Information ............................................................................................. 26

Installation .......................................................................................................... 26

Unpacking ...................................................................................................... 26

Mounting ............................................................................................................. 27

Dimensions .................................................................................................... 27

Cover Jam Screw ........................................................................................... 27

Connections ....................................................................................................... 28

Display & Options Modules .......................................................................... 28

Connectors Labeling ..................................................................................... 29

DC Powered Models (-D Option)................................................................. 29

DC Powered with Battery Backup Models (-A, -B, -P Options) ................... 31

Loop Output Powered Models (-C Option) .................................................. 33

Loop Output Powered with Battery Backup Models (-R, -M, -N Options) ... 34

Wiring Diagrams ................................................................................................ 35

Intrinsically Safe Wiring (-HA and -IS Models) ............................................ 35

I/O Parameter Table .................................................................................... 35

Explosion-Proof Wiring (-HA and -EX Models) ........................................... 36

Pulse Input Connections ............................................................................. 36

DC Power Connections ............................................................................... 37

Digital Input Connections ............................................................................ 37

RS-485 Serial Connections ......................................................................... 37

4-20 mA Output Connections ...................................................................... 38

Solid-State Relay Connections.................................................................... 38

Open Collector Output Connections............................................................ 38

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

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Setup and Programming ................................................................................... 39

Overview ......................................................................................................... 39

CapTouch Buttons ........................................................................................ 39

CapTouch Buttons Delay ............................................................................ 39

Turning Off CapTouch Buttons.................................................................... 39

CapTouch Button Tips & Troubleshooting .................................................. 39

MeterView XL Programming Software ......................................................... 40

CapTouch Buttons and Status Indicators ................................................... 41

Display Functions & Messages .................................................................... 42

Main Menu ...................................................................................................... 46

Setting Numeric Values ............................................................................... 47

Entering the K-Factor (KFACTOR) ...................................................................... 48

Scaling the Pulse Input (SCALE) ....................................................................... 49

Available Engineering Units ........................................................................ 50

Volume Units ............................................................................................... 50

Setting Custom Units (CUSTOM) .................................................................. 51

Setting the Display Features (DISPLAY) ..................................................... 51

Changing the Engineering Units (UNITS) ................................................... 51

Changing the Decimal Point (DEC.PT) ......................................................... 51

Enabling or Disabling Commas on the Bottom Display (COMMA) ................ 52

Display Capabilities Optimization (TOP and BOTTOM) ................................ 52

Using 13 Digits to Display Total .................................................................. 52

Configuring the Display (TOp and BOTTOM) ................................................ 53

Programming the Bargraph (BARGRAPH) .................................................... 54

Programming the Outputs (OUTPUT) ........................................................... 54

Open Collector Outputs

(

OPEN COLLECTR

)

................................................. 55

Solid-State Relay Outputs (RELAY) ............................................................ 60

Isolated 4-20 mA Output (4-20 mA) ............................................................ 67

Output Manual Control (CONTROL) ............................................................. 67

Advanced Features Menu (ADVANCE) .......................................................... 68

Advanced Rate Setup (ADV RATE) ............................................................ 68

Advanced Total and Grand Total Setup (ADV TOTAL & ADV GTOTAL) .... 71

Low-Flow Cutoff (CUTOFF).......................................................................... 73

Gate Function (GATE) ................................................................................. 73

Contact Debounce Filter (FILTER) ............................................................. 73

Enabling Password Protection (PASSWRD) ................................................. 75

Data Log Menu (DATALOG) ......................................................................... 76

Serial Communications (COMM) ................................................................... 79

Programmable Function Keys User Menu (USER) ...................................... 79

Changing System Settings (SYSTEM) ......................................................... 82

Meter Operation ................................................................................................. 83

CapTouch Buttons Operation ...................................................................... 83

CapTouch Buttons ........................................................................................ 83

Function Keys Operation .............................................................................. 84

Digital Input Operation .................................................................................. 84

Maximum/Minimum Readings ...................................................................... 84

Total Reset Capabilities ................................................................................ 84

Total Reset via Digital Input ........................................................................ 84

Total Reset Password Protection ................................................................ 84

Runtime & Cycle Count (INFO) .................................................................... 85

Changing Engineering Units ........................................................................ 85

Batch Controller Operation ............................................................................... 86

Default Batch Control Operation .................................................................. 86

Batch Control Operation Example .............................................................. 86

Manual Batch Control ................................................................................... 89

Automatic Batch Control .............................................................................. 90

Troubleshooting................................................................................................. 91

Reset Meter to Factory Defaults ................................................................... 91

Determining Software Version ..................................................................... 91

Factory Default Settings .............................................................................. 92

Troubleshooting Tips .................................................................................... 93

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

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Table of Figures

Figure 1. Enclosure Dimensions – Front View .................................................... 27

Figure 2. Enclosure Dimensions – Side View ..................................................... 27

Figure 3. Enclosure Dimensions – Bottom View ................................................ 27

Figure 4. Connector Labeling for PD6938-##-##-DNM........................................ 29

Figure 5. Connector Labeling for PD6938-##-##-D2M ........................................ 29

Figure 6. Connector Labeling for PD6938-##-##-D3M ........................................ 30

Figure 7. Connector Labeling for PD6938-##-##-D5M ........................................ 30

Figure 8. Connector Labeling for PD6938-##-##-ANM, -BNM, -PNM ................. 31

Figure 9. Connector Labeling for PD6938-##-##-A2M, -B2M, -P2M ................... 31

Figure 10. Connector Labeling for PD6938-##-##-A3M, -B3M, -P3M ................. 32

Figure 11. Connector Labeling for PD6938-##-##-A5M, -B5M, -P5M ................. 32

Figure 12. Connector Labeling for PD6938-##-##-C3N....................................... 33

Figure 13. Connector Labeling for PD6938-##-##-C5N....................................... 33

Figure 14. Connector Labeling for PD6938-##-##-R3N, -M3N, -N3N ................. 34

Figure 15. Connector Labeling for PD6938-##-##-R5N, -M5N, -N5N ................. 34

Figure 16. Flowmeter Powered by External Supply (Active) ............................. 36

Figure 17. Flowmeter Powered by Internal Sensor Power (5 V @ 5 mA) .......... 36

Figure 18. Self-Powered Magnetic Pickup Flowmeter (Coil).............................. 36

Figure 19. Bi-Directional Flowmeter Connections .............................................. 36

Figure 20. NPN Open Collector Input ................................................................... 36

Figure 21. PNP Sensor with External Power ....................................................... 36

Figure 22. Switch Contact Input (Reed) ............................................................... 36

Figure 23. DC Power Connections ....................................................................... 37

Figure 24. Digital Input Connections ................................................................... 37

Figure 25. RS-485 2-Wire & Ground Serial Connections.................................... 37

Figure 26. RS-485 4-Wire & Ground Serial Connections.................................... 37

Figure 27. 4-20 mA Output Connections ............................................................. 38

Figure 28. Solid-State Relay Connections ........................................................... 38

Figure 29. Open Collector Output Connections.................................................. 38

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

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Disclaimer

The information contained in this document is
subject to change without notice. Precision Digital
Corporation makes no representations or
warranties with respect to the contents hereof;
and specifically disclaims any implied warranties
of merchantability or fitness for a particular
purpose.

• Read complete instructions prior to installation
and operation of the meter.

• This product is not recommended for life support
applications or applications where malfunctioning
could result in personal injury or property loss.
Anyone using this product for such applications
does so at his/her own risk. Precision Digital
Corporation shall not be held liable for damages
resulting from such improper use.

• Failure to follow installation guidelines could
result in death or serious injury. Make sure only
qualified personnel perform the installation.

WARNING

Cancer and Reproductive Harm - www.P65Warnings.ca.gov

Limited Warranty

Precision Digital Corporation warrants this
product against defects in material or
workmanship for the specified period under

“Specifications” from the date of shipment from
the factory. Precision Digital’s liability under this

limited warranty shall not exceed the purchase
value, repair, or replacement of the defective unit.
See Warranty Information and Terms &
Conditions on www.predig.com for complete
details.

Registered Trademarks

All trademarks mentioned in this document are
the property of their respective owners.

© 2023 Precision Digital Corporation.
All rights reserved.

Introduction

The PD6938 ProtEX+ pulse input flow rate/totalizers
can be installed in a variety of areas (hazardous, dirty,
wet, corrosive, hot, or cold) to provide convenient and
informative display of flow rate and total from any
pulse output flowmeter. These instruments will accept
a variety of pulse inputs, including slow pulse rates.
They can be powered from a battery, 9-30 VDC, or
the 4-20 mA output loop, have on-board datalogging
capabilities, are available with explosion-proof and
intrinsically safe approvals, and can be ordered with
optional 4-20 mA output and two relays.

The PD6938, with the addition of its two optional
relays, can also be used as a simple batch controller.

The PD6938 can operate down to -40°C and is
certified by the agencies to be installed in areas that
get as cold as -55°C. The display will cease
functioning below -40°C but no damage will be done
to the instrument.

One of the most convenient features of these
instruments is their dual-line display, which is typically
used to display the flow rate on the top display and
flow total, flow grand total, or a tag on the bottom
display. The top display has five characters and the
bottom display has eight characters for clear
indication of tags, units, or alarm messages. Further
enhancing the display on these instruments is a
20-segment bargraph and backlighting that can turn
red during an alarm condition.

The PD6938 ProtEX+ is available in aluminum and
stainless steel enclosures that are designed for easy
use and installation. The process connection is
available in M20, 3/4" NPT and 1" NPT and there are
two other conduit holes for field wiring. Field wiring is
made to removable screw terminals and the display
module can be oriented in 4 different positions to
accommodate different mounting configurations and
requires no tools to install. The display has been
designed to optimize viewing angle.

Free, PC-based, MeterView XL software that
connects to the meter via a micro-USB cable is
available for programming and setup of the
instruments. Four CapTouch through-glass buttons
are available to operate the instrument without
removing the cover.

All models come equipped with two open collector
outputs and a digital input. There are also models
available with Modbus RTU RS-485 communications,
two solid-state relays, and isolated 4-20 mA analog
output options. The open collector outputs are useful
for alarm indication or pulse output. The digital input
can be used to reset the total, to start/stop a
timer/stopwatch, to start/stop a batch, and more. The
relays can be programmed for alarm indication, on/off
control, or simple batch control.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

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Key Features

2X More Informative Display

The PD6938 display offers a 50% larger display area
and is twice more informative than previous
generations of pulse input meters. Featuring an
alphanumeric dual-line display and a 20-segment
bargraph, reading and understanding process values
is easy and intuitive. The addition of status indicators
provides a quick glance at alarm conditions, relays,
process trends, and more. Predefined display units
give users even more display flexibility. Plus, the high
contrast backlit LCD display is readable from far away
and under various lighting conditions.

Alarm Indication

When an alarm occurs, the display can be
programmed to turn red, flash, and display an alarm
indicator . In addition, a unique custom alarm
message for each of the two relays and two open
collectors can be displayed on the bottom display.
These features can be activated even if no relay or
open collector is connected.

CapTouch Through-Glass
Buttons

The PD6938 is equipped with four capacitive sensors
that operate as through-glass buttons so that it can be
operated without removing the cover (and exposing
the electronics) in a hazardous area. CapTouch
buttons are designed to work under any lighting
condition and to protect against false triggering. They
can be turned off for security via a switch on the
display module.

CapTouch buttons have two modes of operation:
Normal and Delayed. Delayed mode prevents
accidental trigger of the buttons. In the Delayed
mode, the buttons enter into a low sensitivity state
(sleep) and they ignore quick button presses after
20 seconds of inactivity. To wake up the buttons,
press and hold any button for more than 2 seconds,
the buttons respond normally.

Solid State Relays 1-2
Indicators

Predefined
Rate Units

Password Protection

Trend

Indicators

CapTouch Buttons

Self-Calibration

Battery Status Indicators

Total or Grand Total

Indicator

Alarm Indicator

Batch Control Indicators
(Run, Stop, Pause)

20-Segment
Bargraph

Two-Color
Backlight

CapTouch Buttons /
Function Keys

Five 12-Segment

Alphanumeric Characters

0.7" (17.8 mm)

Eight 14-Segment

Alphanumeric Characters

0.4" (10.2 mm)

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

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Commas on 8-Digit Totalizer for
Easy Reading

It may seem like a simple thing, but adding commas
to an eight-digit number makes it easier to read:

Predefined and Custom Units

The PD6938 flow rate/totalizer has the most common
predefined rate and volume units. If the desired unit is
not available, the user can program a custom unit.

14-Segment Characters

Notice how much better letters like “T”, “N” and “K”
appear as 14-segment characters on the bottom display
vs. 7-segment characters found on other meters.

Enable / Disable Backlight

The backlight may be enabled or disabled using the
System - Backlight menu. The backlight is enabled by
default, and it is set up to timeout after 10 seconds
when battery power is used. See Enabling or
Disabling the Backlight (BACKLITE) on page 82 for
details.

Multiple Outputs

• Two open collector outputs (standard)

• Two solid-state relays (optional)

• One 4-20 mA output (optional)

The open collector outputs and relays generally
operate in the same manner, with the major exception
being the open collectors are not available for batch
control and the relays are not available with pulse
features. The open collectors and relays can be
controlled either automatically or manually.

The isolated analog output signal can be configured
to represent the process variable (flow rate, total, or
retransmit). It can also be reverse scaled such that

the meter’s high calibration value outputs 4 mA and
the meter’s low calibration outputs 20 mA.

Password Protection

A password can be set up for programming security to
prevent unauthorized changes to the programmed
parameter settings.

Free MeterView XL
Programming Software

The fastest and easiest way to program the meter is
using the free Meterview XL programming software.
This software greatly simplifies the programming
process and allows the user to save configuration files
for later use.

The meter connects to the PC via a provided micro­USB cable and is powered by the USB connection, so
no additional power is needed during programming.

Easy Wiring & Service

The PD6938 has been designed for easy wiring and
servicing. All connections are made to removable
screw terminal blocks. There are no exposed printed
circuit boards.

Wide Viewing Angle

The window and display module have been optimized
to provide a wide viewing angle of approximately
±40°; nearly twice that of the competition.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

9

Modern and Practical Enclosure

The PD6938 NEMA 4X, IP68 enclosure provides
serious protection from the elements, high impact,
corrosion, and electrical interference. Plus, the
extensive worldwide agency approvals allow it to be
installed virtually anywhere.

Aluminum or Stainless Steel Enclosure

The enclosure is available in copper-free (0.3%),
die-cast aluminum and type 316 stainless steel.

Direct Mounting

The PD6938 features a bottom threaded conduit
opening available in M20, 3/4" NPT and 1" NPT,
which allows easy mounting directly to a flowmeter.
This image shows a battery powered PD6938
mounted to a turbine flowmeter. Even though it is
battery powered, it has a backlight that turns on only
when CapTouch buttons are in use.

Built-In Flange for Pipe Mounting
The built-in mounting flange allows easy mounting to

walls or pipes.

A slot on the back makes it easy to center the unit on
a pipe.

Grounding Screw

A grounding screw is provided on the bottom of the
enclosure.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

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SS Tag Attaching Loop

The enclosure is also equipped with a loop to easily
attach a PDA-SSTAG stainless steel tag.

Tamper-Proof Capability

The instrument can be made tamper-proof by
inserting a wire through the built-in loop on the base
of the enclosure and a hole in the lid of the enclosure
and securing this wire with a lead seal.

Rate/Totalizer Features

Display Flow Rate & Total at the
Same Time

The PD6938 can display flow rate and total at the same
time. In addition, the meter can toggle between the rate
and total and their corresponding units as the following
example illustrates.

Total Limit & Initial Value

The Advanced – Total Count menu allows the digit
limit to be selected between 8-digit (bottom display
only) and 13-digit (uses top and bottom display to
display the full number).
The user can set the initial value at which the total
and grand total should start counting.

Using 13 Digits to Display Total

The top and bottom displays can be set up to display
a 13-digit total.

Note: The number above should be read as

6,843,276,349,187

Total & Rate in Different Units

The user can select to display total in different units
than the rate. For instance, a customer could
measure flow rate in gallons per minute and total in
acre-feet by simply selecting AF (acre-feet) units for
the total. Additionally the user can enter a custom unit
and conversion factor to display the total in any unit of
measure.

Rate in Units Per Second, Minute,
Hour, or Day

The user may select a rate time base in units per
second, minute, hour, or day. The time base is the
amount of time over which the rate parameter will
totalize. For example, if the rate was 10 gallons/min
(and stayed constant for one minute), then the total
would increase by 10 every minute.

4-20 mA Output for Rate or Total

The 4-20 mA output can be assigned to the rate or
the total.

Total Stored in Non-Volatile
Memory

Total and grand total values, and all programmed
settings are stored in non-volatile memory for a
minimum of ten years if power is lost.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

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Total Reset Capabilities

The total and grand total can be reset using a
CapTouch button, an external contact closure on the
digital input, or MeterView XL software. In addition,
both total and grand total reset can be password
protected to prevent unauthorized resets.

Time of Day Total Reset

The total and grand total can be set up to reset at a
time of day every day or any day of the week. The
previous total and grand total are saved prior to
applying the reset command. The previous totals can
be read via the F1 function key and the Modbus
registers.

There are four reset times that can be set up, all
choices allow specifying the reset day and time.

Total Reset via CapTouch Button

The CapTouch function key F2 is set up to reset the
total. If reset grand total is enabled, it is possible for the
user to reset either the total or the grand total without
removing the cover or the need for external devices.

Total Reset via Digital Input

The PD6938’s digital input can also be used to reset the
total or grand total.

Total Reset Password Protection

Total and grand total passwords can be set to prevent
resetting the total or grand total unless a password is
entered. Grand total reset can be disabled through
the meter interface, and it can also be permanently
disabled.

Non-Resettable Grand Total

The user can set up the grand total to be non-resettable by
selecting YES at the PERMLOC menu; see page 72 for
details. Once this is done, the grand total can never be reset.

Batch Control Capabilities

The meter can be equipped with two solid-state relays
that may be set up for batch control. Selecting batch
control for relay 1 enables the batching features on the
meter. The top display changes to show the total and the
bottom display changes to show the batch preset. The
function keys also change for batch control functions
such as F1 starts a batch, F2 opens the preset menu to
allow the preset value to be changed, and F3 stops the
currently running batch. Enabling batch control for
relay 1 allows access to the batch menu under relay 2.
The second relay may be programmed as a preclose
relay or as another batching relay with its own preset
amount.

Manual or Automatic Operation

Batching can be set to either manual or automatic
operation.

If set to automatic, then a delay before the next batch
starts must be programmed.

Count Up or Down Batching

The batch total can be set to count up or down.

G+

DI

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

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Data Logging

The PD6938 is capable of data logging up to 2,032
records, each containing date, time, rate, total, grand
total, and relay & open collector states. The user can
choose what information to log, when, and how to log
it. The log file can be downloaded using the
MeterView XL software and it can be saved in .csv file
format.

The easiest way to set up the data logger is using the
MeterView XL software connected via the micro-USB
port or the RS-485 Modbus connection. There are
many ways to log data using the on-board memory.
Use the MeterView XL software to download the data
or a Modbus application.

• Log time: Every day or any day of the week

• Log time interval: Select the logging interval

• Select to log continuously or stop when full

Data Log Example

The log file is saved in .csv file format and it contains
all the information selected in the data log setup.

Power Options

The PD6938 offers a wide range of power options
including battery, DC with battery backup, DC only,
output loop, or output loop with battery backup. See
Specifications for details on each of the power options
available. See Ordering Information for details on
what power options are available for each hazardous
area approval.

Battery Backup

Select models are available with a battery backup
power option. For these models, the primary power
source is supplied by either DC power or the output
loop, depending on the model. The battery is used
during battery backup operation. If there is a power
failure of the primary power source, the battery will
instantly take over powering the meter. There will be
no display interruption nor any information loss.

Battery Status Indication

Battery indicators on the display alert users of the
power status of the PD6938.

Indicator

State

Description

Flashing

Meter checking battery status

Steady

Meter using battery power

Flashing

Low battery

Designed for Long Battery Life

The PD6938 is designed with power savings in mind
to help extend battery life.

LCD Sleep Mode

LCD sleep mode turns the LCD off after a user
programmable amount of time, while all inputs and
outputs continue working. Press any button for 2
seconds to wake up the display.

CapTouch Delayed Mode

In Delayed mode, the buttons enter into a low
sensitivity state (sleep) after 20 seconds of inactivity.
Press any button for 2 seconds to wake up the
buttons.

Momentary Backlight

The backlight is enabled by default. If the meter is
battery powered, then the backlight is automatically
set up to momentarily turn on for 10 seconds when
any button is pressed.

Turn Meter Off

To extend battery life even more, the meter can be
turned off completely when it is not in use. Press and
hold the Menu button for 5 seconds to turn the meter
on or off and follow the on-screen instructions.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

13

Ordering Information

-HA Models (Dual Hazardous Approved)

Aluminum Enclosure

Loop Output Powered6

Model

Description

PD6938-HA-AL-C3N

Pulse Input Explosion-Proof & Intrinsically Safe Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-HA-AL-C5N

Pulse Input Explosion-Proof & Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA
Analog Output

DC Powered5

Model

Description

PD6938-HA-AL-DNM

Pulse Input Explosion-Proof & Intrinsically Safe Flow Rate/Totalizer, No Options

PD6938-HA-AL-D2M

Pulse Input Explosion-Proof & Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays

PD6938-HA-AL-D3M

Pulse Input Explosion-Proof & Intrinsically Safe Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-HA-AL-D5M

Pulse Input Explosion-Proof & Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA
Analog Output

Stainless Steel Enclosure

Loop Output Powered6

Model

Description

PD6938-HA-SS-C3N

Pulse Input Explosion-Proof & Intrinsically Safe Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-HA-SS-C5N

Pulse Input Explosion-Proof & Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA
Analog Output

DC Powered5

Model

Description

PD6938-HA-SS-DNM

Pulse Input Explosion-Proof & Intrinsically Safe Flow Rate/Totalizer, No Options

PD6938-HA-SS-D2M

Pulse Input Explosion-Proof & Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays

PD6938-HA-SS-D3M

Pulse Input Explosion-Proof & Intrinsically Safe Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-HA-SS-D5M

Pulse Input Explosion-Proof & Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA
Analog Output

Notes:

1. All models come with bargraph, two open collector outputs, and one digital input standard.

2. The meter comes standard with three 3/4" NPT conduit holes.

3. To order models with different conduit holes, add the following at the end of the part number:

a. -21 for M20 conduit holes (e.g. PD6938-HA-AL-DNM-21)
b. -24 for one 1" bottom and two 3/4" NPT conduit holes (e.g. PD6938-HA-AL-DNM-24)

4. Meters with dual hazardous area approval are not available with battery power options.

5. Modbus is standard on all DC powered models.

6. Modbus is not available with loop-powered models.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

14

-IS Models (Intrinsically Safe Approved)

Aluminum Enclosure

Loop Output Powered6

Model

Description

PD6938-IS-AL-C3N

Pulse Input Intrinsically Safe Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-IS-AL-C5N

Pulse Input Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

DC Powered5

Model

Description

PD6938-IS-AL-DNM

Pulse Input Intrinsically Safe Flow Rate/Totalizer, No Options

PD6938-IS-AL-D2M

Pulse Input Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays

PD6938-IS-AL-D3M

Pulse Input Intrinsically Safe Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-IS-AL-D5M

Pulse Input Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

DC Powered with 3xAA Battery Pack (Primary or Backup)5

Model

Description

PD6938-IS-AL-PNM

Pulse Input Intrinsically Safe Flow Rate/Totalizer, No Options

PD6938-IS-AL-P2M

Pulse Input Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays

PD6938-IS-AL-P3M

Pulse Input Intrinsically Safe Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-IS-AL-P5M

Pulse Input Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

Loop Output Powered with 3xAA Battery Pack (Backup)6

Model

Description

PD6938-IS-AL-R3N

Pulse Input Intrinsically Safe Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-IS-AL-R5N

Pulse Input Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

Stainless Steel Enclosure

Loop Output Powered6

Model

Description

PD6938-IS-SS-C3N

Pulse Input Intrinsically Safe Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-IS-SS-C5N

Pulse Input Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

DC Powered5

Model

Description

PD6938-IS-SS-DNM

Pulse Input Intrinsically Safe Flow Rate/Totalizer, No Options

PD6938-IS-SS-D2M

Pulse Input Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays

PD6938-IS-SS-D3M

Pulse Input Intrinsically Safe Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-IS-SS-D5M

Pulse Input Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

DC Powered with 3xAA Battery Pack (Primary or Backup)5

Model

Description

PD6938-IS-SS-PNM

Pulse Input Intrinsically Safe Flow Rate/Totalizer, No Options

PD6938-IS-SS-P2M

Pulse Input Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays

PD6938-IS-SS-P3M

Pulse Input Intrinsically Safe Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-IS-SS-P5M

Pulse Input Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

Loop Output Powered with 3xAA Battery Pack (Backup)6

Model

Description

PD6938-IS-SS-R3N

Pulse Input Intrinsically Safe Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-IS-SS-R5N

Pulse Input Intrinsically Safe Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

Notes:

1. All models come with bargraph, two open collector outputs, and one digital input standard.

2. The meter comes standard with three 3/4" NPT conduit holes.

3. To order models with different conduit holes, add the following at the end of the part number:

a. -21 for M20 conduit holes (e.g. PD6938-IS-AL-PNM-21)
b. -24 for one 1" bottom and two 3/4" NPT conduit holes (e.g. PD6938-IS-AL-PNM-24)

4. Battery powered meters with Intrinsically Safe approval are available only with 3xAA battery power option.

5. Modbus is standard on all DC powered models.

6. Modbus is not available with loop-powered models.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

15

-EX Models (Explosion-Proof Approved)

Aluminum Enclosure

DC Powered with A Cell Battery Pack (Primary or Backup)5

Model

Description

PD6938-EX-AL-ANM

Pulse Input Explosion-Proof Flow Rate/Totalizer, No Options

PD6938-EX-AL-A2M

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays

PD6938-EX-AL-A3M

Pulse Input Explosion-Proof Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-EX-AL-A5M

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

DC Powered with C Cell Battery Pack (Primary or Backup)5

Model

Description

PD6938-EX-AL-BNM

Pulse Input Explosion-Proof Flow Rate/Totalizer, No Options

PD6938-EX-AL-B2M

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays

PD6938-EX-AL-B3M

Pulse Input Explosion-Proof Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-EX-AL-B5M

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

Loop Output Powered6

Model

Description

PD6938-EX-AL-C3N

Pulse Input Explosion-Proof Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-EX-AL-C5N

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

DC Powered5

Model

Description

PD6938-EX-AL-DNM

Pulse Input Explosion-Proof Flow Rate/Totalizer, No Options

PD6938-EX-AL-D2M

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays

PD6938-EX-AL-D3M

Pulse Input Explosion-Proof Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-EX-AL-D5M

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

Loop Output Powered with A Cell Battery Pack (Backup)6

Model

Description

PD6938-EX-AL-M3N

Pulse Input Explosion-Proof Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-EX-AL-M5N

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

Loop Output Powered with C Cell Battery Pack (Backup)6

Model

Description

PD6938-EX-AL-N3N

Pulse Input Explosion-Proof Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-EX-AL-N5N

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

Notes:

1. All models come with bargraph, two open collector outputs, and one digital input standard.

2. The meter comes standard with three 3/4" NPT conduit holes.

3. To order models with different conduit holes, add the following at the end of the part number:

a. -21 for M20 conduit holes (e.g. PD6938-EX-AL-ANM-21)
b. -24 for one 1" bottom and two 3/4" NPT conduit holes (e.g. PD6938-EX-AL-ANM-24)

4. Battery powered meters with Explosion-Proof approval are available only with A and C Cell battery power options.

5. Modbus is standard on all DC powered models.

6. Modbus is not available with loop-powered models.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

16

Stainless Steel Enclosure

DC Powered with A Cell Battery Pack (Primary or Backup)5

Model

Description

PD6938-EX-SS-ANM

Pulse Input Explosion-Proof Flow Rate/Totalizer, No Options

PD6938-EX-SS-A2M

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays

PD6938-EX-SS-A3M

Pulse Input Explosion-Proof Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-EX-SS-A5M

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

DC Powered with C Cell Battery Pack (Primary or Backup)5

Model

Description

PD6938-EX-SS-BNM

Pulse Input Explosion-Proof Flow Rate/Totalizer, No Options

PD6938-EX-SS-B2M

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays

PD6938-EX-SS-B3M

Pulse Input Explosion-Proof Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-EX-SS-B5M

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

Loop Output Powered6

Model

Description

PD6938-EX-SS-C3N

Pulse Input Explosion-Proof Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-EX-SS-C5N

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

DC Powered5

Model

Description

PD6938-EX-SS-DNM

Pulse Input Explosion-Proof Flow Rate/Totalizer, No Options

PD6938-EX-SS-D2M

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays

PD6938-EX-SS-D3M

Pulse Input Explosion-Proof Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-EX-SS-D5M

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

Loop Output Powered with A Cell Battery Pack (Backup)6

Model

Description

PD6938-EX-SS-M3N

Pulse Input Explosion-Proof Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-EX-SS-M5N

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

Loop Output Powered with C Cell Battery Pack (Backup)6

Model

Description

PD6938-EX-SS-N3N

Pulse Input Explosion-Proof Flow Rate/Totalizer, 4-20 mA Analog Output

PD6938-EX-SS-N5N

Pulse Input Explosion-Proof Flow Rate/Totalizer, Two Solid-State Relays & 4-20 mA Analog Output

1. All models come with bargraph, two open collector outputs, and one digital input standard.

2. The meter comes standard with three 3/4" NPT conduit holes.

3. To order models with different conduit holes, add the following at the end of the part number:

a. -21 for M20 conduit holes (e.g. PD6938-EX-SS-PNM-21)
b. -24 for one 1" bottom and two 3/4" NPT conduit holes (e.g. PD6938-EX-SS-PNM-24)

4. Battery powered meters with Explosion-Proof approval are available only with A and C Cell battery power options.

5. Modbus is standard on all DC powered models.

6. Modbus is not available with loop-powered models.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

17

Accessories

Model

Description

PDABAT36C1-PACK

3.6 V Lithium Battery, C-Size

PDABAT36A1-PACK

3.6 V Lithium Battery, A-Size

PDABAT36AA3-PACK

3.6 V Lithium Battery Pack, 3xAA-Cell

PDAPLUG75

3/4" NPT 316 Stainless Steel Conduit Plug with Approvals

PDAPLUGM20

M20 316 Stainless Steel Conduit Plug with Approvals

PDAREDUCER-75M-50F

M-3/4" NPT to F-1/2" NPT Reducer with Approvals

PDAREDUCER-75M-M20F

M-3/4" NPT to F-M20 Reducer with Approvals

PDA8485-I

USB to RS-485 Isolated Converter

PDA1002

6" DIN Rail Mounting Kit

PDA1024-01

24 VDC Transmitter Power Supply for DIN Rail

PDA6846

Steel 2" U-Bolt Kit. All Material: Zinc Plated Steel; (1) U-Bolt for 2" Pipe with (2) Washers,
(2) Lock Washers, and (2) Nuts

PDA6846-SS

Stainless Steel 2" U-Bolt Kit. All Material: Stainless Steel; (1) U-Bolt for 2" Pipe with (2)
Washers, (2) Lock Washers, and (2) Nuts

PDA-MICROUSB

Micro-USB PC Programming Cable (supplied)

PDA-SSTAG

Custom Stainless Steel Tag (see website for convenient ordering form)

• Accessories do not carry hazardous area approvals unless otherwise specified and are thus not suitable for
location in hazardous areas. The use of additional protective devices may allow them to be installed in a safe
area and connected to a device in a hazardous area. User should consult a professional engineer to determine
suitability of these products for their specific application.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

18

PDA1024-01 24 VDC Power Supply

The PDA1024-01 is a DIN rail mounted 1.5 A,
24 VDC power supply that can be used to power
the PD6938 and the 4-20 mA output.

PDA6846 2" U-Bolt Kits

The PDA6846 U-Bolt Kits provide a convenient way to
mount the meter to 1.5" or 2" pipes. They are
available in steel and stainless steel.

PDA-SSTAG Stainless Steel Tag

The PDA-SSTAG is a laser etched stainless steel tag
that can be customized with three lines of text.
Each tag comes with a stainless steel wire and lead
seal for easy mounting wherever you need.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

19

Specifications

Except where noted all specifications apply to operation at +25°C.

Display

Display

Dual-line LCD with backlight.
Both lines: alphanumeric
Top: 0.7" (17.8 mm) 5 digits, 12-segment
Bottom: 0.4" (10.2 mm) 8 characters,
14-segment
Display may be programmed to turn red and
flash a user-defined message on alarm
condition.

LCD Sleep

Never, 1, 2, 5, 10, 20, 60 min
Default: 10 min when battery powered; press
any key for 2 sec to wake up the display.
All inputs and outputs continue working.

Turn Meter
Off/On

Press & hold the Menu key for 5 sec and
follow the on-screen instructions. This feature
helps extend battery life.

On-Screen
Indicators

See CapTouch Buttons and Status Indicators
on page 41 for details.

Top Display

5 digits (-9999 to 99999) or 5 characters (all
capital & most lower-case letters)

Bottom
Display

8 digits (-9,999,999 to 99,999,999; separated
by commas) or 8 characters
(all capital & most lower-case letters)

Backlight

Normal: white LED (enabled by default)
Alarm: red LED (default)
DC powered: steady on
Battery powered: momentary (default: 10 sec)
Output loop powered: varying intensity based
on 4-20 mA output current

Bargraph

20 segments (100% label at top fixed)
Assignable to rate, total, or off
Scale: 0 to 100%

Display
Assignment

Top & bottom displays can be assigned to
rate, total, grand total, etc. See Configuring
the Display (TOp and BOTTOM) on page 53 for
a complete list of assignable parameters.

Decimal Point

Up to four decimal places on top display and
up to seven decimal places on bottom display

Commas

Commas to indicate 1000s
(e.g. 88,987,628) on the bottom display

Alarm
Indication

Programmable: red backlight, flashing display,
alarm symbol , bargraph segment flashes
on alarm.

Custom
Alarm
Messages

Programmable for each relay/open collector:
8 characters maximum; displayed every 10
sec for 1 sec on bottom display. May be
turned off.

Display
Update Rate

Ambient > -10°C: 4 updates/second
Ambient = -20°C: 1 update/2 seconds
From -20°C to -40°C the update rate slows
down 1 second for every -2°C
(e.g. at -24°C, 1 update/4 seconds).
Below -40°C the display is not readable, but
all the inputs and outputs work correctly.

Overrange

Top: 99999; Bottom: 99,999,999 (flashing)

Underrange

Top: -9999; Bottom: -9,999,999 (flashing)

General

Programming
Method

Four CapTouch through-glass buttons when
cover is installed. The CapTouch buttons can
be used with the cover removed.
Free PC-based USB MeterView XL
programming software.

Recalibration

Recommended at least every 12 months.

Environmental

Operating temperature range:

-40 to 75°C (-40 to 167°F)

Storage temperature range:

-55 to 85°C (-67 to 185°F)

Installation temperature range:

-55 to 75°C (-67 to 167°F)
(The display ceases to function, however

inputs and outputs continue to operate)
Relative humidity: 0 to 90% non-condensing
Printed circuit boards are conformally coated

Max / Min
Display

Max / min readings reached by the process
are stored until reset by the user or until
power to the meter is turned off.

Password

There are three separate passwords available
that can be set independently of each other:
Main, Total, and Grand Total. The Main
password prevents access to the meter
Programming Mode. Total and Grand Total
passwords prevent resetting the total and
grand total, respectively.

Non-Volatile
Memory

Total and Grand Total values, and all
programmed settings are stored in non­volatile memory for a minimum of ten years if
power is lost.

Power
Options

9-30 VDC Powered, 2 W max

Battery Powered or
9-30 VDC Powered with Battery Backup

Loop Output Powered (30 VDC max)
Loop Output Powered with Battery Backup

Data Logging

Up to 2,032 records, recorded 4/day at
specific times or at defined time intervals.
Record contains date, time, rate, total, grand
total, and open collectors & relays states.

Data Logging
Modes

Continuous: The log data will wrap around,
erasing the oldest records to save the new
records. Banks of 16 records will be erased at
a time.

Stop when full: The log will stop recording
when full and “LOG FULL” is displayed every
10 sec.

Connections

Removable screw terminal blocks
Display terminals: accept 16 to 30 AWG wire
Relay terminals: accept 12 to 26 AWG wire
4-20 mA output: accept 16 to 30 AWG wire

Tightening
Torque

Display terminals: 2.5 lb-in (0.28 Nm)
Relay terminals: 4.5 lb-in (0.5 Nm)
4-20 mA output terminals: 2.5 lb-in (0.28 Nm)

Overall
Dimensions

5.25" x 5.65" x 4.80" (133 x 144 x 122 mm)
(W x H x D)

Weight

Aluminum: 5.1 lbs (2.3 kg)
Stainless Steel: 9.4 lbs (4.3 kg)

Warranty

3 years parts and labor. See Warranty
Information and Terms & Conditions on

www.predig.com for complete details.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

20

Battery

Battery life is dependent on how the meter is used. Backlight
should only be used momentarily (10 sec on). Modbus should
rarely be used on battery-power, it requires approximately
26 mA. See battery life tables below for details.

-IS Models (Options: P & R) 3xAA-Cell

Battery Type

3.6 V Lithium (Li-SOCl2), non-rechargeable
P/N: PDABAT36AA3-PACK

Battery Life

Operating
Condition
@ 2,000 Hz

Estimated

Service Life

Suggested

Replacement

Interval

Monitoring only,
backlight off

35 months

30 months

LCD sleep*,
minimal CapTouch
use, backlight off

57 months

50 months

100 Hz open
collector 1&2
outputs, minimal
backlight use

24 months

20 months

Battery
Replacement

Replace only with a Precision Digital original
Model PDABAT36AA3-PACK

-EX Models (Options: A & M) A-Size

Battery Type

3.6 V Lithium (Li-SOCl2), non-rechargeable
P/N: PDABAT36A1-PACK

Battery Life

Operating
Condition
@ 2,000 Hz

Estimated

Service Life

Suggested

Replacement

Interval

Monitoring only,
backlight off

17 months

15 months

LCD sleep*,
minimal CapTouch
use, backlight off

28 months

25 months

100 Hz open
collector 1&2
outputs, minimal
backlight use

12 months

10 months

Battery
Replacement

Replace only with a Precision Digital original
Model PDABAT36A1-PACK

-EX Models (Options: B & N) C-Size

Battery Type

3.6 V Lithium (Li-SOCl2), non-rechargeable
P/N: PDABAT36C1-PACK

Battery Life

Operating
Condition
@ 2,000 Hz

Estimated

Service Life

Suggested

Replacement

Interval

Monitoring only,
backlight off

37 months

32 months

LCD sleep*,
minimal CapTouch
use, backlight off

61 months

53 months

100 Hz open
collector 1&2
outputs, minimal
backlight use

26 months

21 months

Battery
Replacement

Replace only with a Precision Digital original
Model PDABAT36C1-PACK

Battery Life with Modbus Continuously On

3XAA-Cell

277 hours

A-Size

138 hours

C-Size

296 hours

*LCD sleep: Press any key to wake up the display. All input
& outputs continue working in LCD Sleep mode.

Enclosure

Material

-AL Models:

ASTM A413 LM6 die-cast aluminum,

copper-free, enamel coated.

-SS Models:

ASTM A743 CF8M investment-cast

316 stainless steel

Gasket

Fluoroelastomer

Rating

NEMA 4X, IP68 explosion-proof

Color

-AL: Blue; -SS: Silver

Window

Borosilicate glass

Conduits

Three 3/4" NPT or M20 threaded conduit
openings. Optionally, the bottom opening can
be supplied with 1" NPT opening. See
Ordering Information on page 13 for details.

Conduit
Stopping
Plug

Sold separately. See Ordering Information on
page 13 for details.

Flange

Built-in flange for wall and pipe mounting.

Tamper-Proof
Seal

Enclosure lid may be secured with
tamper-proof seal.

Instrument
Tag Loop

Built-in loop for securing stainless steel tag

Overall
Dimensions

5.25" x 5.65" x 4.80" (133 x 144 x 122 mm)
(W x H x D)

Weight

Aluminum: 4.8 lbs (2.18 kg)
Stainless Steel: 9.0 lbs (4.08 kg)

ATEX &
IECEx
(Enclosure
only)

Flameproof protection

II 2GD
Ex db IIC Gb
Ex tb IIIC Db
IP66/IP68
Tamb: -55°C to +85°C
Certificate No.: Sira 19ATEX1252U
Certificate No.: IECEx SIR 19.0075U

CSA
(Enclosure
only)

Class I, Division 1, Groups A, B, C, D
Class II, Division 1, Group E, F, G;
Class III
Ex db IIC Gb
Ex tb IIIC Db
Class I, Zone 1, AEx db IIC Gb;
Zone 21, AEx tb IIIC Db
IP66/IP68/TYPE 4X
Tamb: -55°C to +85°C
Certificate No.: 80011200

UL
(Enclosure
only)

Class I, Division 1, Groups A, B, C and D
Class II, Division 1, Groups E, F and G
Class III;
Class I, Zone 1, AEx db IIC Gb
Zone 21, AEx tb IIIC
Ex db IIC Gb
Ex tb IIIC Db
IP66/IP68/TYPE 4X
Tamb: -55°C to +85°C
Certificate Number: E518920

Note: The above approvals are for the enclosure only.
See Hazardous Area Approvals on page 24 for approvals on
the entire instrument.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

21

Pulse Input

Pulse,
Transistor,
Contact
Closure

Pulse or square wave:
0-5 V, 0-12 V, or 0-24 V; TTL; NPN or PNP

Open collector: 100 kΩ pull-up to 2.8 V
Switch contact: 100 kΩ pull-up to 2.8 V
PNP transistor: 100 kΩ pull-down to ground
Active input: 100 kΩ pull-up to 2.8 V

NPN strong: 10 kΩ pull-up to 2.8 V (Do not
use with battery power)

Maximum Frequency: 100 kHz
Minimum Pulse Width: 5 µs

Threshold Setting Low (V) High (V)
Active/NPN 0.5 1.8
Active/NPN High 2.8 4.8

Magnetic
Pickup Coil

Sensitivity: 10 mVp-p to 24 Vp-p
Maximum Frequency: 40 kHz
Note: 10 mVp-p @ 300 Hz max

Sensor
Power

5 VDC @ 5 mA
Enabled in the Advanced – System menu

Minimum
Input
Frequency

0.0001 Hz
Minimum frequency is dependent on high gate
setting (rate display)

Input
Impedance

Pulse input: Greater than 75 k @ 1 kHz.
Open collector/switch: 100 k pull-up to 2.8 V

Contact
Debounce
Filter

Programmable contact debounce filter.
Input signal frequency speed selections:
Disable: Greater than 100 kHz (no filter)
Fast: 1,000 Hz
Medium: 240 Hz
Slow: 100 Hz

Accuracy

Rate: ±0.02% of calibrated span ±1 count
Total: Every input pulse is counted

Temperature
Drift

2 PPM/°C from -40 to 75°C ambient

Function

K-Factor: 0.000001 to 9,999,999
Rate: Linear (2-32 points)

Low-Flow
Cutoff

0.1 to 999,999 or disable. Point below at which
the display always shows zero.

HART
Transparency

The 4-20 mA output does not interfere with
existing HART communications.

Rate/Totalizer

Rate Display

Top display: -9999 to 99999;
Bottom display: -9,999,999 to 99,999,999
(with commas)

Total & Grand
Total Display

Top display: 0 to 99999;
Bottom display: 0 to 99,999,999 (with commas)

13-Digit Total
& Grand Total

Up to 9,999,999,999,999 using both lines
with 13-digit total feature enabled.

Total Decimal
Point

Up to four decimal places on top, up to seven
decimal places on bottom. Total decimal
point is independent of rate decimal point.

Totalizer

Calculates total based on input pulses and
rate units to display total in engineering units.
A custom factor must be programmed if using
custom defined units.

Time Base

Seconds, Minutes, Hours, Days

Totalizer
Rollover

Totalizer rolls over when display exceeds
99,999,999 (9,999,999,999,999 if 13-digit
limit enabled). Relay status reflects display.

Total & Grand
Total Reset

Via CapTouch button, external contact
closure on digital input, automatic based on
time of day, or MeterView XL.

Time of Day
Total & Grand
Total Reset

Four programmable reset times.
The total and grand total can be set up to
reset at a time of day every day or any day.

Previous
Total & Grand
Total

Total & grand total are saved prior to applying
the reset command.
The previous totals can be read via the F1
function key and the Modbus registers.

Total & Grand
Total Reset
Passwords

Total and grand total passwords may be
entered to prevent resetting the total or grand
total unless a password is entered.

Non­Resettable
Grand Total

Grand total reset may be disabled through
the meter interface. Grand total reset may be
permanently disabled by selecting YES at the
PERMLOCK menu.

• Once the Grand Total has been programmed as

“non-resettable” the feature CANNOT be disabled.

Non-Volatile
Memory

Total and Grand Total values are stored in
non-volatile memory for a minimum of ten
years if power is lost.

Batch Control

Methods

Automatic or Manual, count up or count down

Manual Batch
Start

Pressing F1 function key starts the batch

Manual Batch
Pause/Stop

Pressing F3 once pauses the batch,
pressing it twice cancels the batch

Automatic
Batching

The ProtEX+ can be used as an automatic
batch controller where batches run
continuously without operator input

Batching Relay
Operation

Single or dual-relay batching with optional
preclose for dual-stage operation

Batch Preset

Set via F2 function key anywhere between

0.0001 to 99,999 based on batch total
decimal point. If batch total is assigned to
bottom, the preset can be up to 8 digits.

Batch Preclose

For two-stage batch application, a preclose
value can be set to close the main flow line.

Automatic Batch
Restart Delay

1 to 9,999 seconds. The batch will
automatically restart after completion
of the last batch.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

22

Common Open Collector & Relay Specifications

Number

Two open collectors & two relays

High or Low
Alarm

User programmable for high or low alarm

Alarm
Deadband

0-100% FS, user programmable

Output
Assignment

Alarm, Timer, Stopwatch, or Disable

Alarm Output
Source

Assign to rate, total, grand total, or digital
input

On & Off Time
Delay

0 to 9,999 seconds

Fail-Safe
Operation

Independent for each open collector and
relay.
Fail-safe on, the output is on under normal
conditions.
Fail-safe off, the output is on under alarm
conditions.

Alarm
Operation

Automatic, automatic with manual override,
latching (manual reset anytime), latching with
reset after cleared (manual reset only after
alarm has cleared)

Alarm
Indication

Programmable: loop-powered red backlight,
flashing display, alarm symbol , bargraph
segment flashes on alarm.

Custom
Alarm
Messages

Programmable for each relay/open collector:
8 characters maximum; displayed every 10 sec for
1 sec on bottom display. May be turned off.

Alarm
Acknowledge

CapTouch ACK button or external digital
input resets output and screen indication.

Auto
Initialization

When power is applied to the meter, open
collectors and relays will reflect
the state of the input to the meter.

Timer Output

One-shot or Continuous
Off Time Delay: 1 sec to 99:59:59
(hrs:min:sec)
On Time: 1 sec to 99:59:59 (hrs:min:sec)

Stopwatch

Output turns on when started and off when
stopped.

Open Collector Outputs

Rating

Isolated open collector, sinking NPN
5-30 VDC @ 150 mA maximum

Output
Assignment

Pulse, Alarm, Timer, Stopwatch, or
Disable

Pulse Output
Source

Pulse output based on Rate, Total,
Grand Total, or Test Frequency, Alarm,
Timer, Total Reset, Stopwatch on/off, or
Disable

Pulse Output
Factor

0.000001 to 999,999.9

Pulse Width

0.25 ms @ 2 kHz; 500 ms @ 1 Hz;
50% duty cycle

Pulse Output
Frequency

2,000 Hz maximum

Quadrature Pulse
Output

Available for Output 2
(90° behind Output 1) 1000 Hz max

Alarm Output
Source

Assign to Rate, Total, Grand Total or
Digital Input

Solid-State Relays

Rating

250 VAC/VDC @ 0.5 A resistive
38 VA; 250 VAC; 0.3 A pilot duty
(inductive)
13 VA; 250 VDC; 0.3 A pilot duty
(inductive)

Noise
Suppression

Metal oxide varistors across outputs

Relay
Assignment

Alarm, Sample, Timer, Batch, Stopwatch
on/off, or Disable

Alarm Output
Source

Assign to Rate, Total, Grand Total, or
Digital Input

Relay
Runtime

Meter will keep track of how long each
relay has operated and display this
information.

Relay
Cycles

Meter will keep track of how many times
the relays have cycled and display this
information.

4-20 mA Transmitter Output

Accuracy

±0.05% FS ±0.001mA

Output Source

Rate, total; reverse scaling allowed

Scaling Range

1.00 to 23.0 mA

Disable

High impedance state, less than 1 mA

Calibration

Factory calibrated:
0 to 100 GAL/Sec = 4.00 to 20.00 mA

Underrange

1.0 mA, 3.5 mA, 3.8 mA; or Off;
user selectable

Overrange

20.5 mA, 20.8 mA, 23.0 mA, or Off;
user selectable

Isolation

500 V input-to-output

Temperature
Drift

0.003 mA max from -40 to 75°C ambient

External Loop
Power Supply

7.0 VDC to 30.0 VDC maximum

Output Loop
Resistance

10-750 Ω @ 24 VDC; 10-1100 Ω @ 30 VDC
(External resistance to maintain accuracy)

On-Board Digital Input

Function

Remote operation of front-panel buttons,
acknowledge/reset relays, reset total,
reset max/min values, start/stop batch,
etc. See User section of Display
Functions & Messages on page 42 for a
complete list of capabilities.

Contacts

2.1 VDC on contact. Connect normally
open contacts across G and +

Logic Levels

Logic High: 2.4 to 30 VDC (max)
Logic Low: 0 to 0.9 VDC

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

23

Serial Communications

Connection

RS-485, 3-wire; Isolation: 500 V.
Non-isolated micro-USB.

Protocol

Modbus® RTU

Meter Address /
Slave ID

1 - 247

Baud Rate

1,200; 2,400; 4,800; 9,600; 19,200;
38,400; or 57,600 bps.

Transmit Time
Delay

Programmable between 0 and 199 ms

Parity/Stop Bit

Even, odd, or none with 1 or 2 stop bits

Byte-to-Byte
Timeout

Max of 1.5 character times or 2.25 ms

Note: Refer to the ProtEX+ and VantageView+ PD6938
Modbus® Register Tables located at www.predig.com for
details.

MeterView XL Software

Availability

Free download from

www.predig.com/meterviewxl

System
Requirements

Microsoft® Windows® 10 & 11

Communications

USB 2.0 (Standard USB A to Micro USB B)
Cable provided

Configuration

Configure all parameters on the meter.
Configure meters one at a time.

Configuration
Files

Generate with or without meter
connected; Save to file for later use.

USB Power
Connection

The meter is powered by the USB
connection during programming. There
is no need to apply external power.

Note: The meter will not be damaged if
external power is applied to it during
programming.

• The meter should only be connected to a computer while

it is located in a safe area

Data Logging
Report

The on-board data log can be
downloaded via the USB or the RS-485
connection.

Saved as “.csv” file format.

PC Data Logging

MeterView XL can be used to data log
directly to a computer connected to the
meter via the USB or the RS-485
connection. The user can select what to
log and at what interval.

• Rate

• Total

• Grand total

• Open collector triggers

• Relay triggers

• Hold/Unhold outputs

Compatibility

Programs created for VantageView+ and
ProtEX+ can be run on either meter. No
other program sharing is permissible.

To download the latest MeterView XL programming
software and manual, visit predig.com/meterviewxl.

General Compliance

Information

Electromagnetic Compatibility

EMC Emissions

• CFR 47 FCC Part 15 Subpart B Class A

emissions requirements (USA)

• ICES-003 Information Technology

emissions requirements (Canada)

• AS/NZS CISPR 11 Group 1 Class A

ISM emissions requirements
(Australia/New Zealand)

• EN 55011 Group 1 Class A ISM

emissions requirements (EU)

• EN 61000-6-4 Emissions requirements

for Heavy Industrial Environments ­Generic

EMC Emissions
and Immunity

EN 61326-1 EMC requirements for
Electrical equipment for measurement,
control, and laboratory use – industrial use

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

24

Hazardous Area Approvals

-HA Models (Dual Hazardous Approved)

CSA

Explosion-proof for use in:

Class I, Division 1, Groups B, C and D
Dust-ignition proof for use in:
Class II/III, Division 1, Groups E, F and G; T6
Flame-proof for use in:
Class I, Zone 1, Ex d IIC T6
Ta = -55 to 75°C
Enclosure: Type 4X & IP66/IP68
Certificate number: CSA 11 2325749

ATEX

Intrinsically safe for use in:

II 1 G D

Ex ia IIC T4 Ga
Ex ia IIIC T200°C Da
Ta = -55 to 75°C
Enclosure: Type 4X & IP66/IP68
Install per Control Drawing DW2636
(contained within LIM6938-2)
Certificate number: CML 18ATEX2089X

Explosion-proof for use in:

II 2 G D

Ex db IIC T6 Gb
Ex tb IIIC T85°C Db IP68
Ta = -55 to 75°C
Enclosure: Type 4X & IP66/IP68
Certificate number: Sira 10ATEX1116X

IECEx

Intrinsically safe for use in:

Ex ia IIC T4 Ga
Ex ia IIIC T200°C Da
Ta = -55 to 75°C
Enclosure: Type 4X & IP66/IP68
Install per Control Drawing DW2636

(contained within LIM6938-2)
Certificate number: IECEx CML 18.0050X

Explosion-proof for use in:

Ex db IIC T6 Gb
Ex tb IIIC T85°C Db IP68
Ta = -55 to 75°C
Enclosure: Type 4X & IP66/IP68
Certificate number: IECEx SIR 10.0056X

-IS Models (Intrinsically Safe Approved)

ATEX

Intrinsically safe for use in:

II 1 G D

Ex ia IIC T4 Ga
Ex ia IIIC T200°C Da
Ta = -55 to 75°C
Enclosure: Type 4X & IP66/IP68
Install per Control Drawing DW2636
(contained within LIM6938-2)
Certificate number: CML 18ATEX2089X

IECEx

Intrinsically safe for use in:

Ex ia IIC T4 Ga
Ex ia IIIC T200°C Da
Ta = -55 to 75°C
Enclosure: Type 4X & IP66/IP68
Install per Control Drawing DW2636
(contained within LIM6938-2)
Certificate number: IECEx CML 18.0050X

-EX Models (Explosion-Proof Approved)

CSA

Explosion-proof for use in:

Class I, Division 1, Groups B, C and D
Dust-ignition proof for use in:
Class II/III, Division 1, Groups E, F and G; T6
Flame-proof for use in:
Class I, Zone 1, Ex d IIC T6
Ta = -55 to 75°C
Enclosure: Type 4X & IP66/IP68
Certificate number: CSA 11 2325749

ATEX

Explosion-proof for use in:

II 2 G D

Ex db IIC T6 Gb
Ex tb IIIC T85°C Db IP68
Ta = -55 to 75°C

Enclosure: Type 4X & IP66/IP68
Certificate number: Sira 10ATEX1116X

IECEx

Explosion-proof for use in:

Ex db IIC T6 Gb
Ex tb IIIC T85°C Db IP68
Ta = -55 to 75°C
Enclosure: Type 4X & IP66/IP68
Certificate number: IECEx SIR 10.0056X

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

25

ATEX/IECEx Specific Conditions of Use

The following conditions relate to safe installation
and/or use of the equipment.

-HA and -IS Models

• The equipment loop/power port shall be connected

to an intrinsically safe barrier with Uo ≥ 5.8V

• The Pulse and Mag inputs shall not both be
connected to external equipment simultaneously.

• The PD6938-HA-AL and PD6938-IS-AL enclosure is
manufactured from aluminum. In rare cases, ignition
sources due to impact and friction sparks could
occur. This shall be considered during installation,
particularly if the equipment is installed in a Zone 0
location.

• All cable entries into the equipment shall be via cable
glands or conduit which provide a minimum degree
of protection of IP54.

• The equipment may not have 500V isolation
between the circuit and earth. This shall be taken
into account when installing the equipment.

-HA and -EX Models

• The equipment label and epoxy coating may
generate an ignition-capable level of electrostatic
charges under certain extreme conditions. The user
should ensure that the equipment is not installed in a
location where it may be subjected to external
conditions (such as high-pressure steam) which
might cause a buildup of electrostatic charges on
non-conducting surfaces. Additionally, cleaning of
the equipment should be done only with a damp
cloth.

• Flameproof joints are not intended to be repaired.

• All entry closure devices shall be suitably certified as

“Ex d”, “Ex t” and “IP66/68” as applicable. Suitable

thread sealing compound (non-setting, non­insulating, non-corrosive, not solvent based, suitable
for the ambient rating) must be used at the NPT
conduit entries to achieve the IPx8 rating while
maintaining the Ex protection concept.

-EX and -IS Models

• The battery shall not be recharged, in addition, it
shall only be replaced by a Precision Digital battery
with the same part number as the one being
replaced. See Battery specifications on page 20 for
details.

Year of Construction

This information is contained within the serial number
with the first four digits representing the year and
month in the YYMM format.

For European Community:

-HA Models

The PD69XX Series must be installed in accordance
with the ATEX directive 2014/34/EU, the product
certificates CML 18ATEX2089X, Sira 10ATEX1116X,
IECEx CML 18.0050X, IECEx SIR 10.0056X and the
product manual.

-IS Models

The PD69XX Series must be installed in accordance
with the ATEX directive 2014/34/EU, the product
certificates CML 18ATEX2089X, IECEx CML

18.0050X, and the product manual.

-EX Models

The PD69XX Series must be installed in accordance
with the ATEX directive 2014/34/EU, the product
certificates Sira 10ATEX1116X, IECEx SIR 10.0056X
and the product manual.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

26

EU Declaration of

Conformity

For shipments to the EU and UK, a Declaration of
Conformity was printed and included with the product.
For reference, a Declaration of Conformity is also
available on our website www.predig.com/docs.

Safety Information

• Read complete instructions prior to installation
and operation of the meter.

• Hazardous voltages exist within enclosure.
Installation and service should be performed only
by trained service personnel.

• Service requiring replacement of internal
components must be performed at the factory.

• Control room equipment must not use or
generate more than 250 VRMS or VDC.

• Hazardous location installation instructions for
associated apparatus (barrier) must be followed
when installing this equipment.

• For safe installation of an ATEX approved
flowmeter with PD6938 rate/totalizers, the
hazardous location installation instructions for the
flowmeter, PD6938 flow rate/totalizer, and
associated apparatus (barrier) must be
compatible.

• PD6938 powered by the 4-20 mA output loop do
not add capacitance or inductance to the loop
under normal or fault conditions.

• Substitution of components may impair
hazardous location safety.

• Equipment contains non-metallic materials and
therefore special care and consideration should
be made to the performance of these materials
with respect to chemicals which may be present
in a harsh operating environment.

Installation

To access the connectors, remove the enclosure
cover and unclip the display module by pulling it from
the enclosure. The display module may be
disconnected from the options module to facilitate
wiring to the options module.

Refer to Control Drawing DW2636 (contained within

LIM6938-2) for details related to intrinsically safe field

wiring.

Explosion-Proof / Dust-Ignition Proof / Flame-Proof

• Disconnect from supply before opening
enclosure. Keep cover tight while circuits are live.
Conduit seals must be installed within
18" (450mm) of the enclosure.

Unpacking

Remove the meter from box. Inspect the packaging
and contents for damage. Report damages, if any,
to the carrier.

If any part is missing or the meter malfunctions,
please contact your supplier or the factory for
assistance.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

27

Mounting

The PD6938 has a slotted mounting flange that may
be used for pipe mounting or wall mounting.
Alternatively, the unit may be supported by the
conduit using the conduit holes provided. Refer to
Figure 1 and Figure 2.

• Do not attempt to loosen or remove flange bolts
while the meter is in service.

Dimensions

Figure 1. Enclosure Dimensions – Front View

Figure 2. Enclosure Dimensions – Side View

Figure 3. Enclosure Dimensions – Bottom View

Cover Jam Screw

The cover jam screw should be properly installed
once the meter has been wired and tested in a safe
environment. The cover jam screw is intended to
prevent the removal of the meter cover in a flame­proof environment without the use of tools. Using a
M2 hex wrench, turn the screw clockwise until the

screw contacts the enclosure’s base. Turn the screw

an additional 1/4 to 1/2 turn to secure the cover.

• Excess torque may damage the threads, screw
head, and/or wrench.

5.25" (133 mm)

3.35" (85.1 mm)

2.25"

(57.2 mm)

0.32"

(8.2 mm)

5.65"

(144 mm)

4.80"

(122 mm)

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

28

Connections

To access the connectors, remove the enclosure cover and unclip the display module by pulling it from the enclosure.
Signal, backlight, open collector, and digital input connections are made to removable connectors on the display
module. Relays and 4-20 mA output connections (if installed) are made to removable connectors on the options
module mounted in the base of the enclosure. The display module may be disconnected from the options module to
facilitate wiring to the options module. Grounding connections are made to the two ground screws provided on the
base of the enclosure, one internal and one external.

• Observe all safety regulations. Electrical wiring should be performed in accordance with all agency
requirements and applicable national, state, and local codes to prevent damage to the meter and ensure
personnel safety.

• Static electricity can damage sensitive components.

• Observe safe handling precautions for static-sensitive components.

• If the meter is installed in a high voltage environment and a fault or installation error occurs, high voltage may

be present on any lead or terminal.

Display & Options Modules

The display module snaps into built-in rails on the enclosure ensuring a secure and perfect fit every time. No tools are
needed to install or remove it. The options module is screwed into the base of the enclosure. Both modules
completely encase the printed circuit boards.

Display Module

Options Module (Left) and Display Module (Right)

Options Module Mounted on the Bottom of Enclosure

Display Module Mounted on Built-In Rails

(No Tools Required)

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

29

Connectors Labeling

The following graphics show the locations of the connectors for each available configuration.

DC Powered Models (-D Option)

Open Collectors, Digital Input, RS-485, DC Power

Connector

Description

OC1

Open Collector 1

OC2

Open Collector 2

RS-485

RS-485 Modbus RTU

Digital Input

G, +

Power

V+, V- (9-30 VDC)

Pulse Input

Connector

Description

C+

Magnetic Pickup Coil

S-

Signal -

S+

Signal +

SP

Sensor Power (5 V @ 5 mA)

Figure 4. Connector Labeling for PD6938-##-##-DNM

Figure 5. Connector Labeling for PD6938-##-##-D2M

USB

Connection

CapTouch

On/Off

Switch

Ribbon Cable

Connector

–+

OC2

–+

OC1

Open Collector

Outputs

Power

V+V-

Digital

Input

+G

Pulse Input

S- S+SPC+

RS-485

D- GD+

Options Module

USB

Connection

CapTouch

On/Off

Switch

Ribbon Cable

Connector

–+

OC2–+OC1

Open Collector

Outputs

NO

C NO

C

Solid State

Relay 2

Solid State

Relay 1Power

V+V-

Digital

Input+GPulse Input

S- S+SPC+

RS-485

D- GD+

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

30

Figure 6. Connector Labeling for PD6938-##-##-D3M

Figure 7. Connector Labeling for PD6938-##-##-D5M

Options Module

USB

Connection

CapTouch

On/Off

Switch

Ribbon Cable

Connector

–+

OC2

–+

OC1

Open Collector

Outputs

4-20 mA

Output

+

–

Power

V+V-

Digital

Input

+G

Pulse Input

S- S+SPC+

RS-485

D- GD+

Options Module

USB

Connection

CapTouch

On/Off

Switch

Ribbon Cable

Connector

–+

OC2

–+

OC1

Open Collector

Outputs

NO

C NO

C

Solid State

Relay 2

Solid State

Relay 1

4-20 mA

Output

+

–

Power

V+V-

Digital

Input

+G

Pulse Input

S- S+SPC+

RS-485

D- GD+

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

31

DC Powered with Battery Backup Models (-A, -B, -P Options)

Open Collectors, Digital Input, RS-485, DC Power

Pulse Input

Connector

Description

Connector

Description

OC1

Open Collector 1

C+

Magnetic Pickup Coil

OC2

Open Collector 2

S-

Signal -

RS-485

RS-485 Modbus RTU

S+

Signal +

Digital Input

G, +

SP

Sensor Power (5 V @ 5 mA)

Power

V+, V- (9-30 VDC)

Figure 8. Connector Labeling for PD6938-##-##-ANM, -BNM, -PNM

Figure 9. Connector Labeling for PD6938-##-##-A2M, -B2M, -P2M

USB

Connection

CapTouch

On/Off

Switch

Ribbon Cable

Connector

Options Module

–+

OC2

–+

OC1

Open Collector

Outputs

Battery

Connector

Battery

Power

V+V-

Digital

Input

+G

Pulse Input

S- S+SPC+

RS-485

D- GD+

Options Module

USB

Connection

CapTouch

On/Off

Switch

Ribbon Cable

Connector

–+

OC2

–+

OC1

Open Collector

Outputs

NO

C NO

C

Solid State

Relay 2

Solid State

Relay 1

Battery

Connector

Battery

Power

V+V-

Digital

Input

+G

Pulse Input

S- S+SPC+

RS-485

D- GD+

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

32

Figure 10. Connector Labeling for PD6938-##-##-A3M, -B3M, -P3M

Figure 11. Connector Labeling for PD6938-##-##-A5M, -B5M, -P5M

Options Module

USB

Connection

CapTouch

On/Off

Switch

Ribbon Cable

Connector

–+

OC2

–+

OC1

Open Collector

Outputs

4-20 mA

Output

+

–

Battery

Connector

Battery

Power

V+V-

Digital

Input

+G

Pulse Input

S- S+SPC+

RS-485

D- GD+

Options Module

USB

Connection

CapTouch

On/Off

Switch

Ribbon Cable

Connector

–+

OC2

–+

OC1

Open Collector

Outputs

NO

C NO

C

Solid State

Relay 2

Solid State

Relay 1

4-20 mA

Output

+

–

Battery

Connector

Battery

Power

V+V-

Digital

Input

+G

Pulse Input

S- S+SPC+

RS-485

D- GD+

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

33

Loop Output Powered Models (-C Option)

Open Collectors and Digital Input

Pulse Input

Connector

Description

Connector

Description

OC1

Open Collector 1

C+

Magnetic Pickup Coil

OC2

Open Collector 2

S-

Signal -

Digital Input

G, +

S+

Signal +

SP

Sensor Power (5 V @ 5 mA)

Figure 12. Connector Labeling for PD6938-##-##-C3N

Figure 13. Connector Labeling for PD6938-##-##-C5N

Options Module

USB

Connection

CapTouch

On/Off

Switch

Ribbon Cable

Connector

–+

OC2

–+

OC1

Open Collector

Outputs

4-20 mA

Output

+

–

Digital

Input

+G

Pulse Input

S- S+SPC+

Loop Output Power

Options Module

USB

Connection

CapTouch

On/Off

Switch

Ribbon Cable

Connector

–+

OC2–+OC1

Open Collector

Outputs

NO

C NO

C

Solid State

Relay 2

Solid State

Relay 1

4-20 mA

Output

+

–

Digital

Input+GPulse Input

S- S+SPC+

Loop Output Power

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

34

Loop Output Powered with Battery Backup Models (-R, -M, -N Options)

Open Collectors and Digital Input

Pulse Input

Connector

Description

Connector

Description

OC1

Open Collector 1

C+

Magnetic Pickup Coil

OC2

Open Collector 2

S-

Signal -

Digital Input

G, +

S+

Signal +

SP

Sensor Power (5 V @ 5 mA)

Figure 14. Connector Labeling for PD6938-##-##-R3N, -M3N, -N3N

Figure 15. Connector Labeling for PD6938-##-##-R5N, -M5N, -N5N

Options Module

USB

Connection

CapTouch

On/Off

Switch

Ribbon Cable

Connector

–+

OC2

–+

OC1

Open Collector

Outputs

4-20 mA

Output

+

–

Battery

Connector

Battery

Digital

Input

+G

Pulse Input

S- S+SPC+

Loop Output Power

Options Module

USB

Connection

CapTouch

On/Off

Switch

Ribbon Cable

Connector

–+

OC2

–+

OC1

Open Collector

Outputs

NO

C NO

C

Solid State

Relay 2

Solid State

Relay 1

4-20 mA

Output

+

–

Battery

Connector

Battery

Digital

Input

+G

Pulse Input

S- S+SPC+

Loop Output Power

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

35

Wiring Diagrams

Intrinsically Safe Wiring (-HA and -IS Models)

• PD6938 installation must be performed in
accordance with control drawings included in

LIM6938-2, in order to meet agency approval

ratings.

• For ATEX certification, barrier and transmitter
must be ATEX Certified with Entity Parameters

and must be connected per manufacturer’s

instructions.

• Service requiring replacement of internal
components must be performed at the factory.

• Entire meter assembly (electronic assembly) may
be replaced in the field with a unit supplied from
the factory labeled “Field Modification”.

I/O Parameter Table

Pulse Input

Switch Port

Ui = 30 V

Ui = 30 V

Ii = 175 mA

Ii = 175 mA

Pi = 1 W

Pi = 1 W

Ci = 0

Ci = 0

Li = 0

Li = 0

Open Collector Outputs

Sensor Power Output

Ui = 30 V

Ci = 2.2 uF

Ii = 175 mA

Li = 0

Pi = 1 W

Uo = 6.93 V

Ci = 0

Io = 132 mA

Li = 0

Po = 0.19 W

Power Supply Input

mA Output

Ui = 30 V

Ui = 30 V

Ii = 175 mA

Ii = 175 mA

Pi = 1 W

Pi = 1 W

Ci = 0

Ci = 0

Li = 0

Li = 0

Relay Outputs

RS-485 Connection

Ui = 30 V

Ui = 5.9 V

Ii = 1000 mA

Ii = 225 mA

Pi = 1 W

Pi = 0.3 W

Ci = 0.013 uF

Ci = 0

Li = 0

Li = 0

Uo = 11.55 V

Uo = 5.88 V

Io = 1 mA

Io = 54 mA

Po = 0.012 W

Po = 0.08 W

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

36

Explosion-Proof Wiring (-HA and -EX Models)

Pulse Input Connections

Signal connections are made to a four-terminal connector. See Connectors Labeling on page 29. The following
figures show connections to various flowmeter types.

There are no switches or jumpers to set up for the input. Setup and programming are performed through the
CapTouch buttons or PC-based software.

Figure 16. Flowmeter Powered by External Supply

(Active)

Figure 17. Flowmeter Powered by Internal Sensor Power

(5 V @ 5 mA)

Figure 18. Self-Powered Magnetic Pickup Flowmeter

(Coil)

Figure 19. Bi-Directional Flowmeter Connections

Figure 20. NPN Open Collector Input

Figure 21. PNP Sensor with External Power

Figure 22. Switch Contact Input (Reed)

C+ S- S+ SP

Power
Supply

+-

Flowmeter

(Pulse Output)

C+ S- S+ SP

Flowmeter

(Pulse Output)

C+ S- S+ SP

Flowmeter

(Magnetic Pickup Coil)

C+ S- S+ SP

Power

Supply

+-

Flowmeter

(Pulse Output)

G+

DI

Flow Direction Switch

C+ S- S+ SP

NP N

Sen s or

100 kΩ

Int ern al Pu ll -Up

+3.0 V

Pow er

Su pp ly

+-

C+ S- S+ SP

PN P

Sen s or

100 kΩ

Int ern al Pu ll -Do wn

C+ S- S+ SP

Sw it ch

Con tact

100 kΩ

Int ern al Pu ll -Up

+3.0 V

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

37

DC Power Connections

Models with battery power may optionally be connected
to DC power and the battery will function as backup
power when DC is lost. The same power supply may
be used to power other circuits including a PNP-type
sensor, however, to maintain input isolation, a separate
power supply must be used to power the isolated
4-20 mA transmitter output.

Figure 23. DC Power Connections

Digital Input Connections

A digital input is standard on the meter. This digital
input is connected with a normally open contact
across G and +, or with an active low signal applied to
G and +.

Figure 24. Digital Input Connections

RS-485 Serial Connections

The RS-485 three-wire serial connection is standard.
The cabling used for an RS-485 serial
communications network should always be a high­quality cable such as Belden 8162 or Alpha 6203C.
Signal ground is always recommended.

Figure 25. RS-485 2-Wire & Ground Serial Connections

Figure 26. RS-485 4-Wire & Ground Serial Connections

• To connect the meter to the MeterView XL
software using the RS-485 Modbus connection
use a PDA8485 USB to RS-485 converter.

V- V+

Power

Supply

+-

G+

DI

D+ D- G

D+ D- G

Flow

Rate/Totalizer

RS-485

Device

D+ D- G

DO DO DI DI

GND

Flow

Rate/Totalizer

RS-485

Device

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

38

4-20 mA Output Connections

Connections for the 4-20 mA transmitter output are
made to the connector terminals labeled 4-20 mA
Output on Figure 12, page 33. The 4-20 mA output
must be powered from an external power supply.

Figure 27. 4-20 mA Output Connections

Solid-State Relay Connections

Relay connections are made to two-terminal
connectors. Each relay’s C terminal is common only
to the normally open (NO) contact of the
corresponding relay.

Figure 28. Solid-State Relay Connections

Open Collector Output Connections

Open collector output 1 and 2 connections are made
to terminals labeled OC1 and OC2. Connect the
alarm or pulse input device as shown below.

Figure 29. Open Collector Output Connections

-+

Device with

4-20 mA

Input

-+

Power

Supply

+-

CNO

CNO

Load

Load

Power

Relay 1

Relay 2

Power
Supply

-+

-++-

OC2 OC1

Alarm

Indicator/

Pulse

Counter

+

-

External DC

Relay

5-30 VDC

90 mA MAX

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

39

Setup and Programming

The meter is factory calibrated prior to shipment to display

0.00 to 100.00, which corresponds to the pulse input. The
calibration equipment is traceable to NIST standards.

Overview

There are no jumpers to set; setup and programming
is done through the CapTouch buttons or the free
MeterView XL PC-based software.

The meter may be powered via the micro-USB
connection located on the display module for the
purpose of programming only. The backlight will not
work while the meter is powered via the USB
connection.

CapTouch Buttons

The PD6938 is equipped with four capacitive sensors
that operate as through-glass buttons so that it can be
programmed and operated without removing the
cover (and exposing the electronics) in a hazardous
area.

These buttons can be turned off for security by
selecting the Off setting on the switch located on the
side of the display module, close to the Menu button.

To actuate a button, press one finger to the window
directly over the marked button area. When the cover
is removed, the CapTouch buttons can be used after
the meter completes a self-calibrating routine (hand
symbol flashes). The sensors are disabled when
more than one button is pressed, and they will
automatically re-enable after a few seconds (hand
symbol off).

CapTouch Buttons Delay

The CapTouch have two modes of operation: Normal
and Delayed. Use the Delayed mode to prevent
accidental trigger of the buttons. In the Delayed
mode, the buttons enter into a low sensitivity state
(sleep) and they ignore quick button presses after 20
seconds of inactivity. To wake up the buttons, press
and hold any button for more than 2 seconds, the
buttons respond normally.

Turning Off CapTouch Buttons

The CapTouch buttons can be turned off for security
by moving the slide switch located on the display
module to the Off position.

CapTouch Button Tips & Troubleshooting

The CapTouch buttons are designed to work under
any lighting condition and to protect against false
triggering. If the CapTouch buttons are not needed
during operation, they can be turned off (slide switch
to Off).

• To remove cover with power applied (safe area
only) or to clean the window, place your hand
over the buttons; this will temporarily disable the
CapTouch buttons to prevent inadvertent use.

• Keep the window clean.

• Tighten the cover securely.

• Use a password to prevent tampering.

• CapTouch buttons will not work if two or more

buttons are detected as being pressed
simultaneously. Be careful to avoid triggering
multiple buttons or reaching across one button
location to press another.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

40

MeterView XL Programming Software

The fastest and easiest way to program the meter is
using the free Meterview XL programming software.
This software greatly simplifies the programming
process and allows the user to save configuration files
for later use.

The meter connects to the PC via a provided micro­USB cable and is powered by the USB connection, so
no additional power is needed during programming.

To download the latest MeterView XL programming
software and manual, visit predig.com/meterviewxl.

• The meter should only be connected to a
computer while it is located in a safe area.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

41

CapTouch Buttons and Status Indicators

Buttons

Button

Description

Menu

Right Arrow/F1

Up Arrow/F2

Enter/F3

1. Press the Menu button to enter or exit the
Programming Mode at any time.

2. Press or hold the Right-Arrow button to scroll
forward through the menus, select digits during
numeric programming, select characters during
text programming, or decrement the value of a
digit or character selected with the Up-Arrow
button.

3. Press and hold the Right-Arrow button to zero or
clear digits/characters while in data-entry mode.

4. Press or hold the Up-Arrow button to scroll
backwards through the menus or to increment
the value of a digit or character.

5. Press the Enter button to access a menu or to
accept a setting or programmed digit/character
value.

• Avoid touching more than one button at a time,
otherwise the buttons become unresponsive and enter
into a self-calibrating routine. This is indicated by the

flashing hand symbol .

Indicators

Indicator

State

Description

Steady

Process trend arrows

Flashing

Alarm Indicator

Steady

Password protected

Steady

Solid-state relay 1

Steady

Solid-state relay 2

Flashing

CapTouch buttons
self-calibrating (wait)

Steady

PV Bargraph

Flashing

Alarm condition:
Bargraph segment flashes on
alarm

Steady

Displaying Total

Steady

Displaying Grand Total

Steady

Batch is running

Flashing

Automatic batch control:
Batch paused or start delayed

Steady

Batch is stopped

Steady

Batch is paused

Flashing

Meter checking battery status

Steady

Meter using battery power

Flashing

Low battery

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

42

Display Functions & Messages

The meter displays various functions and messages during
setup, programming, and operation. The following table
shows the main menu functions and messages in the order
they appear in the menu.

Display Functions & Messages

Parameter

Action/Setting Description

INPUT TYPE

Select the input type (Flowmeter)

ACTIVE

Select for square wave

NPN

Select for NPN transistor

PNP

Select for PNP transistor

REED

Select for reed switch

COIL

Select for magnetic pickup coil

ACT HIGH

Select for high threshold square
wave (see specs, page 20)

NPN HIGH

Select for high threshold NPN
transistor (see specs, page 20)

NPN STRG

Select for stronger pull-up NPN
transistor (see specs, page 20)

PNP HIGH

Select for high threshold PNP
transistor (see specs, page 20)

KFACTOR

Enter the flowmeter’s K-Factor

OUTPUT

Program the meter’s available
outputs

OPEN COLLECTR

Program the meter’s open
collector outputs

OUTPUT1

Open collector 1 setup

OUTPUT2

Open collector 2 setup

DISABLE

Disable the open collector

PULSE

Program the open collector for
pulse output

ALARM

Program the open collector for
alarm output

TIMER

Program the open collector as a
timer

TOT RST

Program the open collector for
total reset

STPWATCH

Program the open collector to turn
on while the stopwatch is running

MANUAL

Program the open collector to be
always On or Off

MESSAGE

Select ON to display a message
when open collector is on

RELAY

Program the meter’s relay outputs

OUTPUT1

Relay 1 setup

OUTPUT2

Relay 2 setup

DISABLE

Disable the relay

ALARM

Program relay for alarm
functionality

SAMPLE

Program relay for sample
functionality

TIMER

Program relay as a timer

BATCH

Program the relay for batch control
functionality

Display Functions & Messages

Parameter

Action/Setting Description

STPWATCH

Program relay to turn on while the
stopwatch is running

MANUAL

Program the relay to be always On
or Off

MESSAGE

Select ON to display a message
when relay is on

RELAY INFO

View relay runtime and cycle count

4-20 Ma

Program the meter’s 4-20 mA
output

RATE

Transmit a value based on the rate
display

TOTAL

Transmit a value based on the
total display

DISABLE

Disable the 4-20 mA output

CONTROL

Program manual or automatic
operation for the outputs

OC1

Open collector 1

OC2

Open collector 2

RELAY1

Relay 1

RELAY2

Relay 2

4-20 mA

4-20 mA output

AUTO

Set selected output to automatic
operation

MANUAL

Manually control selected output
operation

ADVANCE

Program the meter’s advanced

features

AdV RATE

Advanced rate input programming

KFACTOR

Enter the flowmeter’s K-Factor

SCALE

Scale the input frequency and the
rate display for up to 32 points

PERCENT

Enter bargraph rate percent values

AdVTOTAL

Advanced total programming

COUNT

Program the totalizer functionality

LIMIT

Set the number of digits used for
the total

8-DIGIT

Eight digits max (99,999,999)

13-DIGIT

Thirteen digits max
(9,999,999,999,999) Requires top
and bottom display to display
entire number, total will roll over to
zero when it exceeds the limit.

NEGATIVE

Enable counting negative values
(Available only via front panel)

INITIAL

Set the total to start at a specific
number

RESET

Enable or disable the ability to
reset the total

MANUAL

Disable manual total reset
(default: enabled)

TIME DAY

Enable total reset based on time of
day (Up to 4 times), press Up key
to change the day of the week,
press Right key to change time.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

43

Display Functions & Messages

Parameter

Action/Setting Description

AdV GTOTAL

Advanced grand total
programming

COUNT

Program the totalizer functionality

LIMIT

Set the number of digits used for
the total

8-DIGIT

Eight digits max (99,999,999)

13-DIGIT

Thirteen digits max
(9,999,999,999,999) Requires top
and bottom display to display
entire number, total will roll over to
zero when it exceeds the limit.

NEGATIVE

Enable counting negative values
(Available only via front panel)

INITIAL

Set the total to start at a specific
number

RESET

Enable or disable the ability to
reset the grand total

MANUAL

Enable manual grand total reset
(default: disabled)

TIME DAY

Enable grand total reset based on
time of day (Up to 4 times), press
Up key to change the day of the
week, press Right key to change
time.

PERMLOCK

Set grand total as non-resettable
(Once set, it cannot be changed)

CUTOFF

Set low-flow cutoff

DISABLE

Disable low-flow cutoff

ENABLE

Enable low-flow cutoff

GATE

Enter the gate settings

LOW GATE

Set low gate (this determines the
rate display update)

HIGH GATE

Set high gate (this is used to
display slow pulse rates)

FILTER

Set contact de-bounce filter

DISABLE

No filter, allows max frequency

FAST

Set filter to 1,000 Hz max

MEDIUM

Set filter to 240 Hz max

SLOW

Set filter to 100 Hz max

PASSWRD

Set a password for the meter

MAIN

Program the main meter password

TOTAL

Program the total reset password

GTOTAL

Program the grand total reset
password

DATALOG

Enter the data logger menu

LOG VIEW

View data logs

LOG SETUP

Set up data logs

HOURLY

Log every hour

DAILY

Log daily

INTERVAL

Set log interval

DAY TIME

Set log based on time of day (up to
4 times), select every day or any
day of the week.

Display Functions & Messages

Parameter

Action/Setting Description

EVENT

Set to log based on events: total
reset, grand total reset,
hold/unhold function, open
collectors, and relays status.

LOG MODE

Select Continue when full (oldest
log block replaced with newest
logs) or Stop when full

LOG ERASE

Erase all data logs

COMM

Set up Modbus communications

SLAVE Id

Set the server ID (1 to 247)

BAUD RATE

Select the baud rate

TX DELAY

Set the transmit delay

PARITY

Select the parity: Even, Odd,
None 1, or None 2

MBUS TAG

Enter the Modbus tag

USER

Assign function keys / digital input

F1

Assign F1 function key

F2

Assign F2 function key

F3

Assign F3 function key

DI

Assign digital input

DISP FN

Set the function key or digital input
to display a value

DISPLAY

Cycle max, min, rate, total, and
grand total

D RATE

Display the rate

D TOTAL

Display the total

DISP GT

Display the grand total

PREV TOt

Display the previous total before
the last total reset

PREV GT

Display the previous grand total
before the last grand total reset

PCT.RATE

Display the rate’s percentage

D UNITS

Display the rate, total, and grand
total units

D TAG

Display the tags

DISPMIN

Display the minimum rate value

DISPMAX

Display the maximum rate value

MIN MAX

Display the minimum and
maximum rate value

D FREQ

Display the input frequency

D mAOUT

Display the current mA output
value

MENU FN

Set the function key or digital input
to access a menu

RLYINFO

Go to relay information menu
(INFO)

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

44

TIMER.FN

Set the function key or digital input
to start or stop a timer

STRT.ALL

Start all timers

STOP.ALL

Stop all timers

S.STP.ALL

Start or stop all timers

OC1

Start/stop open collector 1 timer

OC2

Start/stop open collector 2 timer

RLY1

Start/stop relay 1 timer

RLY2

Start/stop relay 2 timer

START

Start the selected timer output

STOP

Stop the selected timer output

STR-STP

Start or stop the selected timer
output

SHORTCUt

Set a shortcut to timer settings
Timer must be set up first

TIMR OC1

Timer open collector 1 settings

TIMR OC1

Timer open collector 2 settings

TIMER R1

Timer relay 1 settings

TIMER R2

Timer relay 2 settings

BATCH.FN

Set the function key or digital input
to batch control

START

Start a batch

STOP

Stop a batch

STR-STP

Start or stop a batch

PRESET

Preset batch amount

ALARM.FN

Set the function key or digital input
to acknowledge an alarm or
access set points

ACK ALL

Acknowledge all active alarms

SETPOINt

Access all output set points

OC1

Access open collector 1

OC2

Access open collector 2

RY1

Access open relay 1

RY2

Access open relay 2

ACK

Acknowledge selected output
active alarm

SETPOINt

Access selected output set point

OC1 SET

Access open collector 1 set point

OC2 SET

Access open collector 2 set point

RLY1 SET

Access relay 1 set point

RLY2 SET

Access relay 2 set point

SWATCH.Fn

Set the function key or digital input
to activate stopwatch

START

Start the stopwatch

STOP

Pause/Stop the stopwatch

STR-STP

Start or stop the stopwatch
(Resets on start)

DATALOG

Set the function key to a data log
function

INTERVAL

Start/stop interval data log

MANUAL

Take a log record

ERASE

Erase all data logs

VIEW

View logs

SHORTCut

Set a shortcut to log view, log
setup, or log erase

HOLD FN

Set the function key or digital input
to hold an output

HOLD.OUT

Hold all outputs while F1-F3 or DI
are active (pressed or on)

UNHOLD

Displayed when hold all outputs
key is released

HLD.UNHLd

Hold/un-hold all outputs
Press once to hold, press again to

release after confirming with YES

OC1+2

Hold/un-hold open collector
outputs

RLY1+2

Hold/un-hold relay outputs

mAOUT

Hold/un-hold 4-20 mA output

HOLD

Hold selected output

HLD.UNHLD

Hold or un-hold selected output

DISABLE

Disable function key or digital input

RST FN

Set the function key or digital input
to reset a value

RESET

Reset min, max, or max/min rate
value

R MIN.MAX

Reset max and min rate value

RST T

Reset the total

RST GT

Reset the grand total

RST T.GT

Reset the total and grand total

HINT

Display hint text on key press and
execute action on next key press

OFF

Turn the hint function off

ON

Turn the hint function on

SYSTEM

Program system settings

AOUTCAL

Calibrate the analog output

DEFAULT

Load factory defaults

BACKLITE

Enable/disable display backlight

ENABLE

Enable the backlight (default)

DISABLE

Disable the backlight

SENS.POWr

Enable sensor power

CAPTOUCH

Select CapTouch buttons mode

NORMAL

CapTouch normal (default)

DELAYED

CapTouch delayed

BATTERY

Access battery menu

DISPLAY

Access battery display settings

BACKLITE

Select backlite timeout

LCD.SLEEP

Select LCD sleep timeout

INDICATr

Display battery indicator

RS-485

Enable/disable RS-485 Modbus or
program RS-485 enable interval

INFO

View meter software version and
model; change the identifier tag

SFT

The software ID number

VER

The software version

MODEL

The meter model number

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

45

ID.TAG

The meter identifier tag
Press Enter to edit tag

TIME

Set the system date & time

DISPLAY

Program the meter’s display

UNITS

Change the display units within the
selected unit class

RATE

Select the rate units

TOTAL

Select the total units

U.MULT

Select the total units multiplier
X1, 100 h, 1000 k, 1.0E^6 M

GTOTAL

Select the grand total units

U.MULT

Select the grand total multiplier
X1, 100 h, 1000 k, 1.0E^6 M

DEC.PT

Change the decimal point location

RATE

Program the rate decimal point

TOTAL

Program the total decimal point

GTOTAL

Program the grand total decimal
point

COMMA

Enable or disable the use of a
comma on the bottom display

ENABLE

Enable comma (default)

DISABLE

Disable comma

BARGRAPH

Turn off or change the bargraph

RATE

Set the bargraph to display the
rate percentage of a user-selected
range

TOTAL

Set the bargraph to display the
total percentage of a user-selected
range

OFF

Turn the bargraph feature off

TOP

Select what to display on the top
display

RATE

Display the rate

RATE+U

Display the rate and its units
alternating

TOTAL

Display the total

TOTAL+U

Display the total and its units
alternating

GTOTAL

Display the grand total

TAG

Display the tag

UNITS

Display the units

PRESET

Display the preset value

STPWATCH

Display the stopwatch

TIMR OC1

Display open collector 1 timer

TIMR OC2

Display open collector 2 timer

TIMER R1

Display relay 1 timer

TIMER R2

Display relay 2 timer

MIN

Display minimum value

MAX

Display maximum value

MIN MAX

Display alternating min and max

TIME – 12H

Display time 12-hour format

TIME – 24H

Display time 24-hour format

DATE

Display date

BOTTOM

Select what to display on the
bottom display

TOTAL

Display the total

TOTAL+U

Display the total and its units
alternating

TOT+TAG

Display the total and its tag
alternating

T+U+RU

Display the total, its units, and the
rate units alternating

GTOTAL

Display the grand total

GT+UNITS

Display the grand total and its
units alternating

GT+TAG

Display the grand total and its tag
alternating

GT+U+RU

Display the grand total, units, and
rate units alternating

RATE

Display the rate

RATE+TU

Display the rate and the total’s
units alternating

RATE+U

Display the rate and its units
alternating

RATE+TAG

Display the rate and its tag
alternating

R UNITS

Display the rate units

T UNITS

Display the total units

TAG

Display the tag

UNITS

Display the units

PRESET

Display the preset value

STPWATCH

Display the stopwatch

TIMR OC1

Display open collector 1 timer

TIMR OC2

Display open collector 2 timer

TIMER R1

Display relay 1 timer

TIMER R2

Display relay 2 timer

MIN

Display minimum value

MAX

Display maximum value

MIN MAX

Display alternating min and max

TAG+RU

Display the tag and rate units
alternating

TAG+TU

Display the tag and total units
alternating

OFF

Disable the bottom display

R PCT

Display the rate’s percentage of
full scale

FREQ IN

Display the input frequency

mA OUT

Display the current mA output
value

TIME – 12H

Display time 12-hour format

TIME – 24H

Display time 24-hour format

DATE

Display date

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Main Menu

The main menu consists of all the meter’s programmable functions: Input, Output, Advanced, and Display.

• Press Menu button to enter Programming Mode then press the Right-Arrow button to move forward through the
menu and the Up-Arrow button to move back.

• Press Menu at any time to go back one level or press & hold to exit and return to Run Mode. Changes made to
settings prior to pressing Enter are not saved.

• Changes to the settings are saved to memory only after pressing Enter/F3 to confirm the setting or pressing
Enter/F3 at the SAVE? screen when available.

Note: The navigation returns to the top

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Setting Numeric Values

The numeric values are set using the Right and Up-Arrow buttons.

1. Press Right-Arrow to select next digit and Up-Arrow to increment digit value. The selected digit will flash.

2. Press and hold Up-Arrow to auto-increment the display value. If you have made a mistake or would like to

enter a new value, select the left-most digit, and press and hold the Right-Arrow button until all digits reset
to zero.

3. Press the Enter button at any time to accept a setting or Menu button to exit without saving changes.

Note: the underscore in the graphic below is provided to show which digit would be flashing.

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Entering the K-Factor (KFACTOR)

The meter may be scaled using the K-Factor, or conversion factor, function. Most flowmeter manufacturers provide
this information with the device. Enter the K-Factor (KFACTOR) menu and select the units defined with the K-Factor
(example: pulses/gal), the decimal point with highest resolution possible, and program the K-Factor value. The meter
automatically calculates the flow rate using the K-Factor value and the units selected. The rate can be displayed in
any time-base and decimal point resolution selected in the Display menu.

• Performing a K-Factor operation will override any scaling programming. Refer to Scaling the Pulse Input (SCALE)
on page 49 for more information on these programming methods.

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Scaling the Pulse Input (SCALE)

Scaling is an alternative calibration method used instead of K-Factor calibration. The multipoint scaling is a great way
of improving the accuracy of a flowmeter application where output frequency and volume are known for various points
of the flow rate.

• The meter is set up at the factory with a K-Factor of 1.000 pulses/gal. If it is necessary to use the multipoint
scaling function (2-32 points) go to the Advance menu and enter the Adv Rate menu. After selecting Scale
function in the Advance menu, the Scale menu is available in the Setup Input menu.

• The meter is factory calibrated prior to shipment to display the rate in gal/sec, which corresponds to the input
frequency in pulses/sec. The calibration equipment is traceable to NIST standards.

• A calibrated signal source is not needed to scale the meter.

• Performing a Scale operation will override any K-Factor programming. Refer to Entering the K-Factor (KFACTOR)

on page 48 for more information on these programming methods.

Enter the Rate Scale menu to scale the meter to display the pulse input.

• Bi-Directional Flow
The meter can be set up to process bi-directional flow, refer to Bi-Directional Flow on page 74 for details.

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Available Engineering Units

The meter has preprogrammed rate and time base
units. The following are the available units to choose
from:

Rate Time Bases (TIME)

/SECOND

Units per second

/MINUTE

Units per minute

/HOUR

Units per hour

/DAY

Units per day

Rate Units (RATE)

GAL/(T)

Gallons per time unit (T)

L/(T)

Liters per time unit (T)

IGAL/(T)

Imperial gallons per time unit (T)

M3/(T)

Cubic meters per time unit (T)

BBL/(T)

Barrels per time unit (T)

BUSH/(T)

Bushels per time unit (T)

cuYD/(T)

Cubic Yards per time unit (T)

cuFt/(T)

Cubic Feet per time unit (T)

cuIn/(T)

Cubic Inches per time unit (T)

LiBBL/(T)

Liquid barrels per time unit (T)

BBBL/(T)

Beer barrels per time unit (T)

HECtL/(T)

Hectoliter per time unit (T)

AF/(T)

Acre-Foot per time unit (T)

CUSTOM/

Custom unit per time unit (T)

• Use custom units for engineering units not listed
or for units in other languages.

Volume Units

Volume Units (VOLUME)

GAL

Gallons

L

Liters

IGAL

Imperial Gallons

M3

Cubic Meters

BBL

Barrels

BUSH

Bushels

cuYD

Cubic Yards

cuFt

Cubic Feet

cuIn

Cubic Inches

LiBBL

Liquid barrels

BBBL

Beer barrels

HECtL

Hectoliter

AF

Acre-Foot

CUSTOM

Custom Unit

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Setting Custom Units (CUSTOM)

When the desired unit class or unit of measure within a class is not available, a custom unit may be programmed. Select the
CUSTOM menu (or CUSTOM unit within a unit class) to enter a custom unit name.

Text values are set using the Right and Up-Arrow buttons. Press Right-Arrow to select next character and
Up-Arrow to increment character value. The selected character will flash. Press and hold the Up or Right-Arrow
buttons to auto-increment or decrement the character. Press Enter to accept the character.

Notes:

• Press and hold the Right-Arrow while no character is being edited to erase all characters to the right of the

flashing character

• Press and hold Up or Right-Arrow to auto-increment or decrement a selected character.

• All text values, including tags and alarm messages, are set in a similar fashion.

Setting the Display Features (DISPLAY)

The meter’s display functions may be programmed using the Display menu. This menu consists of the
following submenus: Units, Decimal Point, Comma, Bargraph, Top, and Bottom.

Changing the Engineering Units (UNITS)

It is possible to change the engineering units without the need to re-scale the meter. When selecting a new unit from
within the DISPLAY menu (e.g. changing from gallons (GAL) to liters (L)), the meter will automatically convert the
display values to display the new unit. Enter the UNITS menu, select a new unit of measure from the list of
predefined units, and press the Enter button. If entering a custom unit (CUSTOM), a custom conversion factor needs
to be entered.

Changing the Decimal Point (DEC.PT)

The decimal point may be set with up to seven decimal places or with no decimal point at all.
Pressing the Right-Arrow moves the decimal point one place to the right until no decimal point is displayed, and then

it moves to the left most position. Pressing the Up-Arrow moves the decimal point one place to the left.
If the dual-scale level feature is selected, the decimal point selections for PV1 & PV2 are enabled.

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Enabling or Disabling Commas on the Bottom Display (COMMA)

The bottom display is set to show a comma
separating the thousands and millions place by
default if a numeric value is being displayed. This
feature can be disabled or enabled using the Comma
menu.

Display Capabilities Optimization (TOP and BOTTOM)

Display Configuration Examples

The meter’s dual-line display can be setup in multiple
ways to provide an extremely informative view of the
process variable being monitored. The following
graphics show typical configurations:

Top Display: Toggle Flow Rate and Rate Units
Bottom Display: Toggle Total Flow and Total Units

Note: To display units as GALLONS, select custom

units and enter the desired text.

Top Display: Flow Rate
Bottom Display: Toggling Between Units and Tag

Dual-Scale Mode:
Top Display: Toggle Rate and GPM Units
Bottom Display: Toggle Rate and CFM Units

Top Display: Maximum Value
Bottom Display: Process Value

Using 13 Digits to Display Total

The top and bottom displays can be set up to display a
13-digit total.

Note: The number above should be read as
6,843,276,349,187

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Configuring the Display (TOp and BOTTOM)

The display is configured using the TOP and BOTTOM
menus in the DISPLAY menu.

The top display (TOP) can display:

• Rate

• Rate and its units alternating

• Total

• Total and its units alternating

• Grand Total

• Tag

• Units

• Preset batch value

• Stopwatch

• Open Collector 1 or 2 Timer

• Relay 1 or 2 Timer

• Minimum Value, Maximum Value, or Both

• Time 12-hour or 24-hour format

• Date

The bottom display (BOTTOM) can display:

• Total

• Total and its units alternating

• Total and tag alternating

• Total, its units, and rate units alternating

• Grand total and its units alternating

• Grand total and tag alternating

• Grand total, units, and rate units alternating

• Rate

• Rate and the total’s units alternating

• Rate and its units alternating

• Rate and tag

• Rate units

• Total units

• Tag

• Units

• Preset batch value

• Stopwatch

• Open Collector 1 or 2 Timer

• Relay 1 or 2 Timer

• Minimum Value, Maximum Value, or Both

• Tag and rate units

• Tag and total units

• Off (Blank)

• Rate percent

• Input frequency

• mA output

• Time 12-hour or 24-hour format

• Date

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Programming the Bargraph (BARGRAPH)

The ProtEX+ Rate/Totalizers come equipped with a bargraph display for applications where a visual representation of

the rate or total’s percentage of full scale is desirable. This feature can be changed to represent either rate, a

percentage of the rate, total, or it can be disabled, using the Bargraph menu (BARGRAPH). If the bargraph is set to
represent total, the total full scale will need to be set.

Programming the Outputs (OUTPUT)

All models come with two open collectors. Depending on the model purchased, the meter may include two solid-state
relays, and one 4-20 mA output. The Output menu will only show options for the available outputs. See Ordering
Information on page 13 for details.

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Open Collector Outputs

(OPEN COLLECTR)

The meter is equipped with two NPN open collector outputs that may be set up for pulse outputs, alarms, timed
pulses, total reset, or disabled.

Pulse outputs can be set to transmit the rate, total, or grand total. Output 2 may be used to generate a quadrature
output based on the other open collector output. An output test mode is also selectable to generate pulses at a
constant programmable frequency.

Alarms are available based on the rate value or the digital input. The alarm status will show on the display even if
the output is not wired.

A timer output (TIMER) turns the open collector on and off at the specified time intervals. The timer can be set as
single-shot or continuous timer.

A total reset output generates a pulse whenever the total is reset, regardless of the reset method used. The On time
is programmable between 0 and 9,999 seconds.

The stopwatch output (STPWATCH) allows the open collector to be manually activated by starting the stopwatch. The
stopwatch count can be displayed on the top or bottom display.

The output may be disabled by selecting DISABLE.
The Open Collector Outputs are programmed in the following manner:

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Pulse Output (PULSE)

Pulse outputs may be assigned to output the rate, total, or grand total at a programmable factor. If the output is
assigned to rate, the factor is a multiplier that determines the number of pulses generated based on the rate. For
example, if the meter display shows 100 gallons/second and the factor is set to 2, the number of pulses generated
per second would be 200. If the output is assigned to total or grand total, the k-factor corresponds to the number of
pulses generated per unit of measure. For example, if the k-factor is 0.001 and the units are gallons, one pulse will
be generated for every 1,000 gallons. The maximum frequency is 2,000 Hz.

Setting output 2 to quadrature will duplicate the other open collector output, but lag by 90 degrees out of phase. The
other output should be programmed as desired for the quadrature output function and must be a pulse (PULSE)
output selection. The quadrature maximum frequency for both outputs is 1000 Hz.

The TEST option will output a fixed number of pulses per second based on the FREQ value entered.

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Alarm (ALARM)

Alarm outputs may be assigned to the rate, total, grand total, or the digital input. When assigned to the rate, the alarm
may be set as either a high alarm or a low alarm. Alarm actions (AUTO, AUTO.MAN, LATCH, L-CLEAR) determine how
and when the alarm should be reset. They operate as follows:

• Automatic (AUTO): Alarm will reset automatically once the alarm condition has cleared.

• Automatic/Manual (AUTO.MAN): Alarm will reset automatically once the alarm condition has cleared but can

also be reset using the Enter (ACK) button (or whichever function key is set to acknowledge) at any time.

• Latching (LATCH): Alarm must be reset manually and can be done so at any time. Press the Enter (ACK)
button at any time to clear the alarm.

• Latching with Reset after Clear (L-CLEAR): Alarm must be reset manually and can only be done so after
the alarm condition has cleared. Press the Enter (ACK) button after the alarm condition has cleared to reset
the alarm.

If the alarm is set to rate, a set and reset point must be programmed. The set point is the display value at which the
alarm will turn on and the reset point is the display value at which the alarm will turn off. If the set point is lower than
the reset point, the alarm will be a low alarm; if the set point is higher than the reset point, the alarm will be a high
alarm. The digital input alarm will trigger whenever the digital input is triggered.

For both the rate and digital input alarms, a delay before the alarm is turned on or off may be set, as well as a
fail-safe feature which reverses the on/off operation of the open collectors.

Alarm states will be displayed on the meter even if no open collector output is physically connected. These may
include a red LED backlight, flashing the rate value (rate alarm only), a programmable alarm message, an alarm
indicator , and flashing bargraph segment.

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Flashing Red Alarm (RED)

The last two lines in the preceding menu flow chart show how to program the display to turn red, flash, and display a
message when an alarm occurs.

Timer (TIMER)

The timer output may be set to generate the timed pulse only once (ONESHOT) or continuously (CONT).
The timer output produces a constant width pulse at a constant frequency, if set as continuous timer. Program the Off

Delay (OFF.DLAY) from 1 second to 99 hours 59 minutes and 59 seconds. This is the time it takes from selecting
START to turning on the output and for how long the output is off in continuous mode.

Program the On Time (ON TIME) for the active low pulse from 1 second to 99 hours 59 minutes and 59 seconds
(pulse width). This is the period of time for which the output will remain on.

Select Start (START) to begin outputting the constant timed pulse.
Select Stop (STOP) to end outputting the constant timed pulse.
Function keys or the digital input may be assigned to start and stop timer functions (see the USER menu in the

Advanced Menu).

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Stopwatch (STPWATCH)

The stopwatch function may be used to manually run and control a process for a specific time interval up to 99 hrs.,
59 min, and 59 seconds. The stopwatch function may be assigned to any open collector. There are three settings
needed to use the function effectively.

1. Assign stopwatch to either top or bottom display

2. Assign the open collector to control the process (on/off)

3. Assign a function key or digital input to start/stop the stopwatch

Application Example

To maintain consistency of a product, it is necessary to take and test samples at different times throughout the day.
The stopwatch function is used to open and close a solenoid valve to know the exact amount of time needed to
complete the desired sample. Once this is determined, the timer function can be used to automatically take a sample
(batch) based on the time determined using the stopwatch function.

Setup: Assign the following to Stopwatch Function

• Bottom display

(see pages 51 & 53 for details how to change the display)

• Relay 1

(see pages 54 & 60 how to change Open Collector and Solid-State Relay functionality)

• F3: Start/Stop

(see pages 76 & 80 for details on how to change the function keys)

Procedure

• Press F3 to start the stopwatch; relay 1 turns on and the process starts running.

• Press F3 to stop the stopwatch; relay 1 turns off and the process stops.

• The bottom display indicates the time it took to complete the sample.

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Solid-State Relay Outputs (RELAY)

The meter is optionally equipped with two solid-state relays that may be set up for alarms, sample, timer, batch
control, or stopwatch. Alternatively, they may be disabled.

Alarms are available based on the rate, total, grand total, or the digital input. The alarm status will show on the
display even if the output is not wired.

Sample will engage the relay for a programmed period of time when either the total or the grand total have reached
a programmed amount.

A timer output (TIMER) turns the relay on and off at the specified time intervals. The timer can be set as single-shot
or continuous timer.

For use in batch control applications, the meter relays must be set to batch. This will enable the batch control features
of the meter.

The stopwatch output (STPWATCH) allows the relay to be manually activated by starting the stopwatch. The
stopwatch count can be displayed on the top or bottom display.

The output may be disabled by selecting DISABLE.

• During setup, the relays do not follow the input and they will remain in the state found prior to entering the

Relay menu.

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Relay Menu

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Alarm (ALARM)

Alarm outputs may be assigned to the rate, total, grand total, or the digital input. When assigned to the rate, the alarm
may be set as either a high alarm or a low alarm. Alarm actions (AUTO, AUTO.MAN, LATCH, L-CLEAR) determine how
and when the alarm should be reset. They operate as follows:

• Automatic (AUTO): Alarm will reset automatically once the alarm condition has cleared.

• Automatic/Manual (AUTO.MAN): Alarm will reset automatically once the alarm condition has cleared but can

also be reset using the Enter button (or whichever function key is set to acknowledge).

• Latching (LATCH): Alarm will not reset automatically even if the alarm condition has cleared. Press the
Enter button at any time to acknowledge the alarm.

• Latching with Reset after Clear (L-CLEAR): Alarm must be reset manually and can only be done so after
the alarm condition has cleared. Press the Enter (ACK) button after the alarm condition has cleared to reset
the alarm.

If the alarm is set to rate, a set and reset point must be programmed. The set point is the display value at which the
alarm will turn on and the reset point is the display value at which the alarm will turn off. If the set point is lower than
the reset point, the alarm will be a low alarm; if the set point is higher than the reset point, the alarm will be a high
alarm. If the alarm is set to total or grand total, only a set point needs to be programmed. The digital input alarm will
trigger whenever the digital input is triggered.

For all alarms, a delay before the alarm is turned on or off may be set, as well as a failsafe feature which will inverse
the on/off programming.

Alarm states will be displayed on the meter even if no relay output is physically connected. The alarm indicator will
display as well as optional red LED backlight, flashing rate, total, or grand total value (rate, total, or grand total alarms
only), and a programmable alarm message.

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Sample (SAMPLE)

A relay set to sample will trigger when the total or grand total value has incremented by a programmed amount.
The relay can be programmed to stay on for a specified amount of time.

For example: if a relay is set to sample the total with a COUNT of 1,000 and a TIME of 10 seconds, the relay will
engage for 10 seconds whenever the total has incremented by 1,000 (e.g. 1000, 2000, 3000).

Timer (TIMER)

The timer output may be set to generate the timed pulse only once (ONESHOT) or continuously (CONT). The timer
output produces a constant width pulse at a constant frequency, if set as continuous timer.

Program the Off Delay (OFF.DLAY) from 1 second to 99 hours 59 minutes and 59 seconds. This is the time it takes
from selecting START to turning on the output and for how long the output is off in continuous mode.

Program the On Time (ONTIME) for the active low pulse from 1 second to 99 hours 59 minutes and 59 seconds
(pulse width). This is the period of time for which the output will remain on.

Select Start (START) to begin outputting the constant timed pulse. Select Stop (STOP) to end outputting the constant
timed pulse. Function keys or the digital input may be assigned to start and stop timer functions (see the USER menu
in Advanced).

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Batch Control (BATCH)

Selecting batch control for relay 1 enables the batching features on the meter. The top display is changed to show the
total and the bottom display is changed to display the preset batch amount. The function keys are changed so that F1
starts a batch, F2 opens the preset menu to allow the preset value to be changed, and F3 stops the currently running
batch. Enabling batch control for relay 1 allows access to the batch menu under relay 2 (this menu does not appear
by default).

Batch Control Relay 1

The batch total can be set to count UP or DOWN. The batch MAXIMUM is the max preset amount that can be batched.
Batching can be set to either manual or automatic operation (MANUAL or AUTO). If setting batching to automatic, a
delay before the next batch is started must be programmed. The PRESET amount is the value at which the batch will
stop and can be programmed up to the value assigned in the MAXIMUM menu. An on and off delay may be set for
batching relays.

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Batch Control Relay 2

The BATCH option only appears under relay 2 if relay 1 has also been set to batch control. The second relay may be
programmed as a preclose relay or as another batching relay with its own preset amount.

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Stopwatch (STPWATCH)

The stopwatch function may be used to manually run and control a process for a specific time interval up to 99 hrs.,
59 min, and 59 seconds. The stopwatch function may be assigned to any relay. There are three settings needed to
use the function effectively.

1. Assign stopwatch to either top or bottom display

2. Assign the relay to control the process (on/off)

3. Assign a function key or digital input to start/stop the stopwatch

Application Example

To maintain consistency of a product, it is necessary to take and test samples at different times throughout the day.
The stopwatch function is used to open and close a solenoid valve to know the exact amount of time needed to
complete the desired sample. Once this is determined, the timer function can be used to automatically take a sample
(batch) based on the time determined using the stopwatch function.

Setup: Assign the following to Stopwatch Function

• Bottom display

(see pages 51 & 53 for details how to change the display)

• Relay 1

(see pages 54 & 60 how to change Open Collector and Solid-State Relay functionality)

• F3: Start/Stop

(see pages 76 & 80 for details on how to change the function keys)

Procedure

• Press F3 to start the stopwatch; relay 1 turns on and the process starts running.

• Press F3 to stop the stopwatch; relay 1 turns off and the process stops.

• The bottom display indicates the time it took to complete the sample.

Runtime & Cycle Count (INFO)

The relay information menu shows runtime and cycle count for each relay. These values may be cleared at any time
by selecting the Clear option (CLEAR?).

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Isolated 4-20 mA Output (4-20 mA)

The 4-20 mA menu is used to scale the isolated 4-20 mA output based on display values. This menu is not present
on models without a 4-20 mA output option.

The 4-20 mA analog output (if equipped) can be scaled to provide a 4-20 mA signal for the rate or total display range.
The output may be disabled (DISABLE) and will only output the minimum signal.

Overrange and underrange values determine what mA signal the meter will output if the input is below the 4 mA
output scaled point or the display is above the 20 mA output scaled point. This value may be set to 1 mA, 3.5 mA,

3.8 mA, 20.5 mA, 20.8 mA, 23 mA, or disabled.
No equipment is needed to scale the analog output; simply program two display values and corresponding mA output

signals.

Rate or Total (RATE or TOTAL)

To scale the analog output, enter display value 1 and a corresponding analog output value for this display, then enter
display value 2 and a corresponding analog output value for this display value. This will provide a linearly scaled
analog output.

Output Manual Control (CONTROL)

The Control menu is used to control the open collector outputs, 4-20 mA analog output, and the relays manually,
ignoring the input. Each open collector, relay, and analog output can be programmed independently for manual
control. Selecting automatic control sets all relays and analog output for automatic operation.

After selecting manual control for a specific output, you can set the output value. To change the output value, return
to the Control menu, select the output to control, select manual control, and enter a new value.

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Advanced Features Menu (ADVANCE)

To simplify the setup process, functions not needed for most applications are located in the Advanced Features
menu. The options under advanced features include advanced rate, total, and grand total setup, cutoff, gate, filter,
password, data log, communications, user function key programming, and system settings.

Refer to Display Functions & Messages on page 42 for complete list of the advanced features menu.

Advanced Rate Setup (ADV RATE)

The Advanced Rate menu contains options to apply input signal calibration using a K-Factor or multi-point scale.

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Using MeterView XL

MeterView XL makes programming quick and easy; select the input type, scale the input using the multi-point
linearization or enter the k-factor value corresponding to the connected flowmeter. The multi-point scaling can be
exported in .csv file format, the saved files can be imported into other meters.
The complete configuration can be read from a connected meter, saved, loaded, or printed.

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Multi-Point Linearization (LINEAR)

Up to 32 linearization points can be selected for rate under
the SCALE function. Multi-point linearization can be used
to linearize the input and improve the accuracy of a
flowmeter. The easiest way to enter multi-point
linearization values is using the MeterView XL software.

The input frequency and rate values can also be entered
using the CapTouch buttons.

MeterView XL showing the multi­point linearization feature. Up to
32 points can be selected.

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Advanced Total and Grand Total Setup (ADV TOTAL & ADV GTOTAL)

The advanced total and grand total menu contain the count (COUNT) and reset (RESET) menus. The count menu
allows the digit limit to be selected between 8-digit (bottom display only) and 13-digit (uses top and bottom display to
display full number) and the initial value at which the total or grand total should start counting.

When using a 13-digit total or grand total, press the function key assigned to display (default: F1) to view the full
amount once the value has exceeded 100,000,000 (decimal places are automatically truncated). If a 13-digit total or
grand total is displayed on the bottom display and the value has exceeded eight digits, the truncated value will flash
to indicate that it is not the complete value. To display 13-digit grand total, assigned the top and bottom display to
grand total.

The reset menu is used to enable or disable the reset of the total and grand total.

Reset Total & Grand Total

The total and the grand total can be reset manually, using a function key, the digital input, or a Modbus command.
The totals can also be reset automatically at specified days and time; up to four day and time can be set up. The
totals are saved to non-volatile memory prior to executing the reset command. The previous total and grand total are
available for viewing using the function key assigned to Display (F1: Default). The previous totals are also available
via the Modbus registers.

Time of Day Total Reset

The total and grand total can be set up to reset at a time of day every day or any day of the week. The previous total
and grand total are saved prior to applying the reset command.

There are four reset times that can be set up, all choices allow specifying the reset time.

• DAY: Resets every day at the specified time

• SUN - SAT: Resets on the selected day at the specified time

• M-F: Resets Monday through Friday at the specified time

• To select the day press the Up key, to select the time press the Right key

• Manual reset can be enabled regardless of the reset time of day setting

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Non-Resettable Grand Total

The grand total reset may be permanently disabled by selecting YES at the PERMLOC menu after disabling grand total
reset.

• Use caution when selecting the PERMLOC feature as once the grand total reset has been permanently locked, it
cannot be unlocked.

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Low-Flow Cutoff (CUTOFF)

The low-flow cutoff feature allows the meter to be programmed so that the output at low flow rates always displays
zero on the meter. The cutoff value may be programmed from 0.0 to 99999. The meter will display zero below the
cutoff value. The cutoff can be disabled to display negative values.

Gate Function (GATE)

The gate function is used for displaying slow pulse rates. Using the programmable gate, the meter can display pulse
rates as slow as 1 pulse every 9,999 seconds (0.0001 Hz). The gate function can also be used to obtain a steady
display reading with a fluctuating input signal.
There are two settings for the Gate, low gate (LOW GATE) and high gate (HI GATE).

Low Gate (LOW GATE)

For most applications, low gate setting should be left at 1 second. Increase low gate setting to obtain a steadier rate
display. The rate display will update in accordance with the low gate setting, for example if low gate is set at 10, the
display will update every 10 seconds; changes in rate between updates will not be reflected until next display update.
The total is updated faster and independent of the low gate setting.

High Gate (HI GATE)

Set the high gate value to correspond to the highest expected pulse period (lowest pulse rate). For instance if the
meter must display a rate when there is 1 pulse coming into the meter every 10 seconds, set the high gate to 11
seconds. When the signal is removed from the meter, the display will show the last reading for 11 seconds; then it will
read zero. The maximum high gate value is 9,999 seconds, which allows the display of a 0.0001 Hz frequency.

Contact Debounce Filter (FILTER)

The filter function (FILTER) can be used for applications where the meter is set up to count pulses generated by
switch contacts. These are the settings and their maximum frequencies:

Disable: Greater than 100 kHz (no filter)
Fast: 1,000 Hz
Medium: 240 Hz
Slow: 100 Hz

The medium filter ignores signals faster than 240 Hz max, or pulse widths less than 2 ms at 50% duty cycle. The slow
filter ignores signals higher than 100 Hz, or pulse widths less than 5 ms at 50% duty cycle.

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Bi-Directional Flow

The meter can be set up to process bi-directional flow by doing the following:

1. Connect the bi-directional switch from the flowmeter to the digital input terminals of the PD6938

2. Set up the digital input (DI) to activate the flow function: Reversed or Forward
The flow direction function is activated when the switch is closed (Logic: Low)

Reverse = Negative rate is displayed, total decreases
Forward = Positive rate is displayed, total increases

3. Disable the low-flow cutoff feature

4. Enable negative count in the Advanced Total and Grand Total menus, if total is expected to go negative

C+ S- S+ SP

Power

Supply

+-

Flowmeter

(Pulse Output)

G+

DI

Flow Direction Switch

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Enabling Password Protection (PASSWRD)

The Password menu is used for programming security to prevent unauthorized changes to the programmed
parameter settings or undesired resetting of the total or grand total. There are three separate passwords available
that can be set independently of each other: Main, Total, and Grand Total. The Main, Total, and Grand Total
passwords prevent access to the meter Programming Mode. Total and Grand Total passwords prevent resetting of
the total and grand total, respectively.

To set a password, enter the Password menu and program a five-digit password. When a password has been
enabled, the lock icon will display in the upper-left side of the display. For instructions on how to program numeric
values see Setting Numeric Values on page 47.

Making Changes to a Password Protected Meter

If the Main password is enabled, the meter will display the message LOCKED when the Menu button is pressed. If
the Total or Grand Total passwords are enabled, the meter will display the message LOCKED when trying to reset or
change the total or grand total. Press the Enter button while the message is being displayed and enter the correct
password to gain access to the menu. After exiting Programming Mode, the meter returns to its password protected
condition.

Disabling Password Protection

To disable the Main, Total, or Grand Total passwords, access the Password menu and clear the desired password
either by pressing and holding the Right Arrow button until all digits reset to zero or manually changing all of the digits
to zero. When the Enter button is pressed, the meter will display UNLOCKED and will no longer require a password to
access Programming Mode, or a password to reset or change the total or grand total, depending on which password
was cleared.

Note: If the meter is password protected and the password has been forgotten, the password may be overridden
using the master password: 50865

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Data Log Menu (DATALOG)

The Data Log menu is used to set up, view, and erase the data log. The user can choose what information to log,
when, and how to log it. The PD6938 is capable of data logging up to 2,032 records. The log file can be downloaded
using the MeterView XL software and it can be saved in .csv file format.

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Data Log Setup with MeterView XL

The easiest way to set up the data logger is using the MeterView XL software connected via the micro-USB port or
the RS-485 Modbus connection. There are many ways to log data using the on-board memory. Use the MeterView
XL software to download the data or a Modbus application.

• Log time: Every day or any day of the week

• Log time interval: Select the logging interval

• Select to log continuously or stop when full

There are many events upon which a log can be taken.

• Total and grand total reset

• Hold/Unhold outputs

• Open collector trigger

• Relay trigger

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Data Log Example

The log file is saved in .csv file format and it contains all the information selected in the data log setup.

• Information header

• Date & time

• Log sequence

• Log source

• Rate, total, and grand total with units

• Alarm state

• Open collector and relay state

• The function keys and the digital input can be used to log manually at any time.

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Serial Communications (COMM)

The Communications menu is used to view and setup serial parameters necessary for communication via Modbus
RTU. The PD6938 can be used as a Server-only device on an RS-485 network. The meter address (Server ID) may
be programmed between 1 and 247. When using more than one meter in multi-drop mode, each device must have a
unique Server ID.

The baud rate and parity selected must match the settings for all other devices on the network. The baud rate may be
set to 1,200; 2,400; 4,800; 9,600; 19,200; 38,400; or 57,600 bps.

The transmit delay may be set between 0 and 199 ms.
The parity can be set to even, odd, or none with 1 or 2 stop bits.
A Modbus Tag can be programmed to differentiate between multiple units on the network.
Refer to the ProtEX+ and VantageView+ PD6938 Modbus® Register Tables located at www.predig.com for details.

Programmable Function Keys User Menu (USER)

The User menu allows the user to assign the CapTouch buttons function keys F1, F2, and F3, and the digital input
(located on the input signal connector) to access some of the menus or to activate certain functions immediately (e.g.
reset max & min, hold relay states, etc.). This allows the meter to be greatly customized for use in specialized
applications.

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Function Keys & Digital Input Available Settings

Refer to the following table for descriptions of each
available function key or digital input setting.

Display

Description

DISP FN

Set the function key or digital input to
display a value

DISPLAY

Cycle grand total, previous total,
previous grand total, max, min, rate,
and total

D RATE

Display the rate

D TOTAL

Display the total

DISP GT

Display the grand total

PREV TOt

Display the previous total

PREV GT

Display the previous grand total

PCT.RATE

Display the rate’s percentage based

on the bargraph scale

D UNITS

Display rate, total, and grand total
units

D TAG

Display the tags

DISPMIN

Display the minimum rate value

DISPMAX

Display the maximum rate value

MIN MAX

Display the minimum and maximum
rate value

D FREQ

Display the current input frequency

D mAOUT

Display the current mA output value

MENU FN

Set the function key or digital input to
access a menu

RLYINFO

Go to relay information menu (INFO)

MANCTRL

Go to output control menu
(CONTROL)

TIMR OC1

Open collector 1 timer

TIMR OC2

Open collector 2 timer

TIMER R1

Relay 1 timer

TIMER R2

Relay 2 timer

TIMER.FN

Set the function key or digital input to
start or stop a timer

STRT.ALL

Start all timers

STOP.ALL

Stop all timers

S.STP.ALL

Start or stop all timers

OC1

Start/stop open collector 1 timer

OC2

Start/stop open collector 2 timer

RLY1

Start/stop relay 1 timer

RLY2

Start/stop relay 2 timer

START

Start the selected timer output

STOP

Stop the selected timer output

STR-STP

Start or stop the selected timer
output

BATCH.FN

Set the function key or digital input to
batch control

START

Start a batch

STOP

Stop a batch

Display

Description

STR-STP

Start or stop a batch

PRESET

Preset batch amount

ALARM.FN

Set the function key or digital input to
acknowledge an alarm

ACK

Acknowledge all active alarms

SETPOINT

Set all output set point

SETPT.OC1

Set open collector 1 set point

SETPT.OC2

Set open collector 2 set point

SETPT.R1

Set relay 1 set point

SETPT.R2

Set relay 2 set point

SWATCH.FN

Set the function key or digital input to
activate stopwatch

START

Start the stopwatch

STOP

Pause/Stop the stopwatch

STR-STP

Start or stop the stopwatch

DATALOG

Set the function key or digital input to
activate data log function

INTERVAL

Set the function key or digital input to
activate interval data log

START

Start interval data log

STOP

Stop interval data log

STR_STP

Start/Stop interval data log

MANUAL

Set the function key or digital input to
activate manual data log at anytime

ERASE

Set the function key or digital input to
erase the data log

VIEW

Set the function key or digital input to
activate view the data log

ALL

View all logs

HOURLY

View hourly logs

DAILY

View daily logs

INTERVAL

View interval logs

DAY TIME

View time of day logs

MANUAL

View manual logs

EVENT

View event logs, select:
All events, total reset, grand total

reset, total & grand total reset, open
collectors, relays, power-up, or
hold/unhold

SHORTCut

Set the function key or digital input to
go to a data log menu

SETUP

Go to data log setup

ERASE

Go to erase data log

VIEW

Go to view data log

HOLD FN

Set the function key or digital input to
hold an output

HOLD.OUT

Hold all outputs

HLD.UNHLD

Hold or un-hold all outputs

OC1+2

Hold/un-hold open collector outputs

RLY1+2

Hold/un-hold relay outputs

mAOUT

Hold/un-hold 4-20 mA output

HOLD

Hold selected output

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Display

Description

HLD.UNHLD

Hold or un-hold selected output

CTRL FN

Set the function key or digital input to
activate the control function

AUTO

Set the function key or digital input to
return all outputs to automatic mode

OC1-OC2

Set the function key or digital input to
control the open collector output:
automatic, on, off, toggle on/off,
alternate, or momentary

RY1-RY2

Set the function key or digital input to
control the relay output: automatic,
on, off, toggle on/off, alternate, or
momentary

SHORTCut

Set the function key or digital input to
go to the output control menu

BATTRY.Fn

Set the function key or digital input to
activate the battery function

RS-485

Set the function key or digital input to
turn on, or on/off the Modbus RS-485
communications with battery power

DISABLE

Disable the function key or digital
input

RST FN

Set the function key or digital input to
reset a value

RESET

Reset min, max, or max/min PV
value

R MIN.MAX

Reset max and min PV value

Enabling the Function Key Hint Feature (HINT)

Enabling the function key hint feature will cause a hint
message to be displayed when pressing the F1, F2,
or F3 function keys. This text gives a brief description
of what the button is programmed to do. Pressing that
function key a second time will execute that action.

The hint feature does not affect the digital input (DI)
which is intended for immediate execution.

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Changing System Settings (SYSTEM)

The System menu contains the following menus:

Analog Output Calibration, Restore Factory Defaults,
Backlight, Sensor Power, CapTouch Buttons
Operation Mode, Battery, Information, and Date &
Time.

Note: The Analog Output Calibration menu is
available only if the option is installed.

Analog Output Calibration (AOUTCAL)

To perform the analog output calibration, it is
recommended to use a milliamp meter with a
resolution of at least 0.1 µA to measure the output
current. The values saved internally during this
procedure are used for scaling the 4-20 mA output in
the Setup menu.

4-20 mA Output Calibration Procedure

1. Go to the Advanced Features menu and
navigate to the SYSTEM menu and press
Enter. Navigate to AOUTCAL and press Enter.

2. The display will show 4 mA. The ProtEX+ mA
output should now be close to 4 mA. Enter the
actual value read by the digital mA meter on
the bottom display and press Enter.

3. The display will show 20 mA. The ProtEX+ mA
output should now be close to 20 mA. Enter
the actual value read by the digital mA meter
on the bottom display and press Enter.

4. The ProtEX+ will now calculate the calibration
factors and store them.

5. Press Menu to exit.

Enabling or Disabling the Backlight (BACKLITE)

The backlight may be enabled or disabled using the
System - Backlight menu. The backlight is enabled by
default; if the meter is DC powered, the backlight is
constantly on. If the meter is battery powered, the
backlight is on according to the setting selected under
the System – Battery - Display menu.

CapTouch Buttons Operation Mode (CAPTOUCH)

CapTouch buttons have two modes of operation:
Normal and Delayed. Delayed mode prevents
accidental trigger of the buttons. In the Delayed
mode, the buttons enter into a low sensitivity state
(sleep) and they ignore quick button presses after 20
seconds of inactivity. To wake up the buttons, press
and hold any button for more than 2 seconds, the
buttons respond normally.

Battery Operation (BATTERY)

To maximize the battery life of the meter, it is
important to set the display, backlight, and RS-485
operation according to what is best for the application.
These are the default settings:

• Backlight on: 10 seconds

• LCD Sleep: 10 minutes

• Battery Indicator: Off

• Modbus RS-485: Disabled

Viewing System Information (INFO)

System information, such as software (firmware)
number and version, model number, and system tag,
may be viewed in the INFO menu. Press the Right
Arrow button to cycle through all available meter
information. Press Menu to go back to the previous
menu.

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Meter Operation

The meter is equipped with four CapTouch through­glass buttons. These buttons allow meter operation
without removing the cover and exposing the
electronics in a hazardous area.

Three CapTouch buttons labeled F1, F2, and F3 can
be programmed as function keys to perform a variety
of meter functions simply by pressing on the glass
over the button. These include resetting the total,

resetting the meter’s relays or open collectors,

starting and stopping timers, displaying max/min
values and starting/stopping batches. See Function
Keys & Digital Input Available Settings on page 80 for
a complete list of settings available.

A digital input is available on the meter and it may
function in a similar fashion as the function keys to
allow remote operation of a single task.

The max & min readings (peak & valley) reached by
the process can be displayed either continuously by
assigning it to a display line in the Display menu, or
momentarily by pressing the F1 key (default) or
assign it to any of the other function key or the digital
input.

Pressing the F1 key cycles through various display
values (e.g. Grand total, max, min); press the Enter
key to lock the display in the current process value
and press the Enter key again to unlock the display.

The relay information menu shows runtime and cycle
count for each relay.

Change the display units within the selected unit class
at any time without the need to re-scale the meter.
Select the desired units via the UNITS menu in the
DISPLAY menu, and the meter automatically converts
the display values to the new unit of measure.

CapTouch Buttons Operation

Button

Description
(Default Settings)

Press to enter or exit Programming
Mode, view settings, or exit max/min

readings.

Press to display grand total. Continue
pressing to cycle through max, min,
rate, and total displays.

Press to access the Reset menu.
Press F1 to scroll through the options.
Press F3 to reset the currently
displayed parameter.

Press to acknowledge all manually
resettable relays or open collectors.

Press to lock/unlock the display value
after pressing the F1 key.

CapTouch Buttons

The PD6938 is equipped with four capacitive sensors
that operate as through-glass buttons so that it can be
programmed and operated without removing the
cover (and exposing the electronics) in a hazardous
area.

These buttons can be turned off for security by
selecting the Off setting on the switch located on the
side of the display module, close to the Menu button.

To actuate a button, press one finger to the window
directly over the marked button area. When the cover
is removed, the CapTouch buttons can be used after
the meter completes a self-calibrating routine (hand
symbol flashes). The sensors are disabled when
more than one button is pressed, and they will
automatically re-enable after a few seconds (hand
symbol off).

The CapTouch buttons are designed to work under
any lighting condition and to protect against false
triggering. If the CapTouch buttons are not needed
during operation, they can be turned off (slide switch
to Off).

• To remove cover with power applied (safe area
only) or to clean the window, place your hand
over the buttons; this will temporarily disable the
CapTouch buttons to prevent inadvertent use.

• Keep the window clean.

• Tighten the cover securely.

• Use a password to prevent tampering.

• CapTouch buttons will not work if two or more

buttons are detected as being pressed
simultaneously. Be careful to avoid triggering
multiple buttons or reaching across one button
location to press another.

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Function Keys Operation

During operation, the programmable function keys
operate according to the way they have been
programmed in the Advanced Features – User menu.
The table under CapTouch Buttons Operation on
page 83 shows the factory default settings for F1, F2,
and F3.

A hint message may be enabled to provide a
description of what each function key does prior to
executing their assigned function. See Enabling the
Function Key Hint Feature (HINT) on page 81.

Digital Input Operation

A digital input is standard on the meter. This digital
input is programmed identically to function keys F1,
F2, and F3. The input is triggered with a contact
closure between DI+ and DI-, or with an active low
signal. During operation, the digital input operates
according to the way it has been programmed in the
Advanced Features – User menu. Factory default
setting is to reset total.

Maximum/Minimum Readings

The max & min readings (peak & valley) reached by
the process can be displayed either continuously or
momentarily.

Display momentarily by pressing the F1 function key
(default) or assigning to any of the other function keys
or to the digital input in the User menu.

Display continuously by pressing the Enter button
while the max/min is being displayed to lock the
display. Press Enter again to unlock.

Any of the F1-F3 function keys (buttons) and the
digital input can be programmed to reset the max &
min readings. The meters are set at the factory to
display the max reading by pressing the Right
Arrow/F1 button and to use the Up-Arrow/F2 button to
access the Reset menu. Press the Right Arrow button
to cycle through the available parameters to reset.

Top Display: Process Value
Bottom Display: Max & Min

Total Reset Capabilities

The total and grand total can be reset using a
CapTouch button, an external contact closure on the
digital input, or MeterView XL software. In addition,
both total and grand total reset can be password
protected to prevent unauthorized resets.

Time of Day Total Reset

The total and grand total can be set up to reset at a
time of day every day or any day of the week. The
previous total and grand total are saved prior to
applying the reset command. The previous totals can
be read via the F1 function key and the Modbus
registers.

There are four reset times that can be set up, all
choices allow specifying the reset day and time.

Total Reset via CapTouch Button

The CapTouch function key F2 is set up to reset the
total. If reset grand total is enabled, it is possible for the
user to reset either the total or the grand total without
removing the cover or the need for external devices.

Total Reset via Digital Input

The PD6938’s digital input can also be used to reset the

total or grand total.

Total Reset Password Protection

Total and grand total passwords can be set to prevent
resetting the total or grand total unless a password is
entered. Grand total reset can be disabled through
the meter interface, and it can also be permanently
disabled. See Bi-Directional Flow on page 74 for
details.

Non-Resettable Grand Total

The user can set up the grand total to be non-resettable by
selecting YES at the PERMLOC menu; see page 72 for
details. Once this is done, the grand total can never be reset.

G+

DI

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Runtime & Cycle Count (INFO)

The relay information menu shows runtime and cycle
count for each relay. These values may be cleared at
any time by selecting the Clear option (CLEAR?). If
the cycle count or runtime values need to be changed
on a frequent basis, it would be convenient to set up a
CapTouch button or the digital input to simplify this
process.

Note: See the menu tree under Solid-State Relay
Outputs (RELAY) on page 60 for complete menu

structure on this feature.

Meter displaying the
amount of time a relay
has been activated

Meter displaying the
number of times a
relay has cycled

Changing Engineering Units

During operation of the meter, it is possible to change
the display units within the selected unit class without
the need to re-scale the meter. The UNITS menu in the
DISPLAY menu allows the unit of measure to be
changed (e.g. from gallons/second (GAL/s) to
liters/second (L/s)) and the meter will automatically
convert the display values to the new unit of measure.
If entering a custom unit (CUSTOM), a custom
conversion factor will need to be entered. See
Changing the Engineering Units (UNITS) on page 51.

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Batch Controller Operation

Selecting batch control for relay 1 enables the
batching features on the meter. The top display is
changed to show the total and the bottom display is
changed to display the preset batch amount. The
function keys are changed so that F1 starts a batch,
F2 opens the preset menu to allow the preset value to
be changed, and F3 stops the currently running batch.
Enabling batch control for relay 1 allows access to the
batch menu under relay 2 (this menu does not appear
by default). Refer to page 87 for details to setup the
batch controller features.
The PD6938 has two open collector outputs that can
used for alarm indication. A 4-20 mA output option is
also available for retransmitting the process variable.

Default Batch Control Operation

The following describes the operation of the three
operating keys as programmed with default settings.
The digital input can be used to start and stop the
batch using a momentary pushbutton. See examples
for Manual Batch Control on page 89 and Automatic
Batch Control on page 90.

START Key (F1)

Press the START button to begin a new batch
process. Press the START button to resume a batch
that has been stopped.

BATCH Key (F2)

Press the Batch button to access the Preset (batch
amount) menu. Program the batch with the arrow
keys and confirm with the Enter key.

STOP Key (F3)

Press the STOP key once during a batch to pause.
Press the STOP key while paused to stop and cancel
the batch.

• Only the STOP Key is Enabled when a Batch
is Running. During a batch process, only the

pause/stop functions are operational, other
keys are deactivated.

Batch Control Operation Example

The following example shows how two-stage manual
batch control functions with a PD6938. This setup will
establish a 55-gallon preset for the batch, with a main
valve (high flow) that will close at 50 gallons, and a
trickle valve (low or restricted flow) that will close at
55 gallons. Because the first batch overruns by 0.10,
the batch preset will be changed to 54.90 for the next
batch to compensate for overrun.

Two-Stage Manual Batch Control Setup Using Relays 1 & 2

The following table shows the parameters as they
appear within the OUT RELAY menu.

Parameter

Setting

Function

RELAY
OUTPUT 1

RLY 1
BATCH

Press Enter to assign relay
1 batch parameters.

BATCH
COUNT

UP or

DOWN

Setup batch to count up
or down.

BATCH
MAXIMUM

100.00
GAL

This setting prevents the
operator from entering a
preset value that exceeds
a safety limit for the batch
process.

BATCH
MODE

MANUAL

AUTO

Press Enter to select
manual or automatic batch
control.

BATCH
PRESET

55.00 GAL

Enter the batch size.

BATCH
DELAY

ON & OFF

Enter the On & Off time
delays for relay 1,
if desired.

RELAY
OUTPUT 2

RLY 2
BATCH

Press Enter to assign relay
2 batch parameters.

BATCH
PRECLOSE

YES
PRECLOSE

5.00

Set the pre-close value to
5 to close the valve being
controlled by relay 2 so it
closes five gallons before
reaching the preset.

BATCH
DELAY

ON & OFF

Enter the On & Off time
delays for relay 2,
if desired.

RELAY
MESSAGE

MSG
RELAY 1

Enter a message to be
displayed while relay 1 is
on, if desired.

MSG
RELAY 2

Enter a message to be
displayed while relay 2 is
on, if desired.

If only one-stage batch control is desired, do not
assign relay 2 to batch. The following pages show
illustrations of how the above settings control the
batch operation. The display assignment shown is the
default.

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Batch Control Relay 1

The batch total can be set to count UP or DOWN.
The batch MAXIMUM is the max preset amount that can be batched.
Batching mode can be set to either manual or automatic operation (MANUAL or AUTO). If setting batching to

automatic, a delay before the next batch is started must be programmed.
The PRESET amount is the value at which the batch will stop and can be programmed up to the value assigned in the

MAXIMUM menu.
An on and off delay may be set for batching relays.

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Batch Control Relay 2

The BATCH option only appears under relay 2 if relay 1 has also been set to batch control. The second relay may be
programmed as a preclose relay or as another batching relay with its own preset amount.

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Manual Batch Control

The manual batch control feature is used for batch processes that the operator wants to start manually. It can also be
used where the batch size needs to be manually adjusted for each batch. The batch can be controlled by the button on
the meter or the digital input.

System Setup

Both valves are closed with an
empty barrel in place. The batched
total is displayed in the upper
display, the preset is selected for
the lower display.

Batch Start

The START button or (F1) is
pressed. Both valves open. The
barrel begins to fill.

Preclose Valve

When the batch total reaches a
value of 50.00 (Preset [55.00] –
Pre-close [5.00]) the full-flow valve
closes. The fill rate of the tank slows
as a result.

Completed Batch

When the batch is complete, the
restricted-flow valve closes. If
overrun occurs, then the preset
must be adjusted to compensate for
the overrun. The next batch will only
start after the START button or (F1)
is pressed.

Overrun Correction

To compensate for overrun in the
previous batch, adjust the preset to

54.90, so that the next batch is
accurate (55.00).

Manual Start of Next Batch

A new, empty, barrel is put in place
and the START button or (F1) is
pushed to manually start the next
batch.

Change Batch Size

While the process is stopped, a new
preset fill amount may be selected
with the Batch key (F2) for a
different size barrel.

Pause/Stop

At any time, press the STOP button
or Stop key (F3) once to pause the
process, or twice to cancel the
batch, which stops the process.

Resume Batch

If the batch has been paused, then
press START button or (F1) to
resume the batch process.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

90

Automatic Batch Control

The automatic batch control feature is used for batches that start automatically once the previous batch is completed.
There is no opportunity for the operator to change the batch size between batches. The batch can be controlled by
the button on the meter or the digital.

System Setup

Both valves are closed with an
empty barrel in place. The batched
total is displayed in the upper
display, the preset is selected for
the lower display.

Batch Start

The START button or (F1) is
pressed. Both valves open. The
barrel begins to fill.

Preclose Valve

When the batch total reaches a
value of 50.00 (Preset [55.00] –
Pre-close [5.00]) the full-flow valve
closes. The fill rate of the tank slows
as a result.

Completed Batch

When the batch is complete, the
restricted-flow valve closes. If
overrun occurs, then the preset
must be adjusted to compensate for
the overrun.

Start Delay

After the batch is completed, the
operator removes the full barrel and
places an empty barrel; the new
batch starts automatically after 60
seconds (Time Delay).

Automatic Start of Next Batch

The new batch begins automatically
after 60 seconds, both relays
activate and both valves open.

Pause

At any time, press the STOP button
or Stop key (F3) once to pause the
process.

Resume Batch

If the batch has been paused, then
press START button or (F1) to
resume the batch process.

Stop Process

At the end of the shift, press STOP
button or Stop key (F3) twice to stop
the batch process.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

91

Troubleshooting

This product is a highly sophisticated instrument with
an extensive list of features and capabilities. If the
CapTouch buttons are used to program the meter, it
can be a difficult task to keep everything straight. That
is why we strongly recommend the use of the free

MeterView XL software for all programming activities.

A cable is provided to use the MeterView XL software
for programming the meter.

If you have programmed the meter with the CapTouch
buttons and it is not working as intended, try
re-programming the meter using the MeterView XL
software.

Reset Meter to Factory Defaults

When the parameters have been changed in a way
that is difficult to determine what’s happening, it might
be better to start the setup process from the factory
defaults. This can be accomplished using MeterView
XL software or with the CapTouch buttons.

To load factory defaults:

1. Press the Menu button to enter

Programming Mode.

2. Press the Right-Arrow button twice and

press Enter to access the Advanced menu.

3. Press the Up-Arrow button and press Enter

to access the System menu.

4. Press the Right-Arrow button and press

Enter to access the Default menu.

5. Press Enter twice in quick succession. The

meter will load default settings and restart.

Determining Software Version

To determine the software (firmware) version of a
meter:

1. Press the Menu button to enter
Programming Mode.

2. Press the Up-Arrow button twice and press
Enter to access the Advanced menu.

3. Press the Up-Arrow button and press Enter
to access the System menu.

4. Press the Up-Arrow button twice and press
Enter to access the Info menu.

5. Press the Right-Arrow button to cycle
through the meter information. When done,
press the Menu button to return to the
previous menu or press & hold Menu to exit
to Run mode.

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

92

Factory Default Settings

The following table shows the factory setting for most
of the programmable parameters on the meter.

Parameter

Display

Default Setting

Input Menu

Input Type

INPUt TYPE

Active

K-Factor

RatE KFACTOR

1.0000

Rate Units

UNITS

Gallons/second

Rate Scale

RAtE SCALE

If selected in Advance
Rate menu

Input 1

INP 1

0.000 pulses/sec

Display 1

DSP 1

0,000,000

Input 2

INP 2

10,000.00 pulses/sec

Display 2

DSP 2

100.00

Output Menu

Open Collector
Output 1

OUTPUT 1

Disabled

Pulse Factor

FACTOR

1.0

Test Frequency

FREQ

100

Alarm

ALARM

Rate

Alarm Action

ACTION

AUTO

Set Point

SET

20.00

Reset Point

RESET

10.00

Alarm On Delay

DELAY ON

0 seconds

Alarm Off Delay

DELAY OFF

0 seconds

Alarm Failsafe

FAILSAFE

OFF

Red LED

RED

ON

Flash rate

FLASH

ON

Alarm Message

MSG

ON

Message Text

MSG EDIT

ALARM 1

Timer Off Delay

OFF.DLAY

1 minute

Timer On Time

ON TIME

1 second

Timer Mode

MODE

Continuous

Open Collector
Output 2

OUTPUT 2

Disabled

Set Point

SET

40.00

Reset Point

RESET

30.00

Message Text

MSG EDIT

ALARM 2

Relay Output 1

RELAY 1

Disabled

Alarm

ALARM

Rate

Alarm Action

ACTION

AUTO

Set Point

SET

70.00

Reset Point

RESET

60.00

Alarm On Delay

DELAY ON

0 seconds

Alarm Off Delay

DELAY OFF

0 seconds

Alarm Failsafe

FAILSAFE

OFF

Red LED

RED

ON

Flash rate

FLASH

ON

Alarm Message

MSG

ON

Message Text

MSG EDIT

ALARM 3

Parameter

Display

Default Setting

Sample Count

TOTAL COUNT

1,000 gallons

Sample Time

TOTAL TIME

10 seconds

Batch Count

BATCH COUNT

Up

Batch Max

BATCH MAXIMUM

10,000

Batch Mode

BATCH MODE

Manual

Batch Preset

BATCH PRESET

1,000

Batch On Delay

DELAY ON

0 seconds

Batch Off Delay

DELAY OFF

0 seconds

Timer Off Delay

OFF.DLAY

1 minute

Timer On Time

ON TIME

1 second

Timer Mode

MODE

Continuous

Relay Output 2

RELAY 2

Disabled

Set Point

SET

90.00

Reset Point

RESET

80.00

Message Text

MSG EDIT

ALARM 4

4-20 mA Output

4-20 mA

Rate

Advanced Menu

Signal
Conditioning
Function

FUNCTION

Linear (2 pts)
Count Limit

COUNT LIMIT

8-Digit Total

Count Initial

COUNT INITIAL

0

Total Reset

TOTAL RESET

Enabled

GTotal Reset

GTOT RESET

Disabled

Non-Resettable
Grand Total

PERMLOCK

No

Low Cutoff

CUTOFF

Enabled: 0

Filter

FILTER

2.0 seconds

Filter Bypass

BYPAS

0.4 PCT

Main Password

MAIN

00000 (Unlocked)

Total Password

TOTAL

00000 (Unlocked)

GTot Password

GTOTAL

00000 (Unlocked)

Function Key 1

F1

Display

Function Key 2

F2

Reset

Function Key 3

F3

Acknowledge

Digital Input

DI

Reset Total

Hint Feature

HINT

Disabled

Totalizer

TOTAL

Enabled

Backlight

BACKLIGHT

Enabled

CapTouch

CAPTOUCH

Normal

Display Menu

Unit of Measure

UNITS

Rate: GAL/S
Total: GAL

Decimal Point
Location

DEC.PT

Rate: 2; Total: 1;
Grand Total: 0

Comma

COMMA

Enabled

Top Display

TOP

Rate

Bottom Display

BOTTOM

Total

PD6938 Ex-Proof & I.S. Pulse Input Flow Rate/Totalizer

Instruction Manual

93

Troubleshooting Tips

Certain sequences of events can cause unexpected results. To solve these issues, it is best to start fresh from factory defaults and
use the manual as a step by step programming guide, rather than a random approach to programming. To reset the meter to factory
defaults, see Factory Default Settings on page 92. In addition, for best results, we recommend using the free MeterView XL software
for all programming needs.

Symptom

Check/Action

No display at all

Check:

1. Check if DC power supply is on and it provides 9-30 VDC to the meter.

2. If DC or battery power is OK, the meter might be off: Press & hold the menu key to
turn it on; follow the on-screen instructions.

3. If battery powered, check if the LCD is in sleep mode: Press & hold any key for more
than 3 seconds to wake-up.

4. If battery powered, check if the meter is off: Press & hold the Menu key for 5
seconds to turn the meter on.

Not able to change setup or
programming, LOCKED is
displayed

The meter is password-protected. Enter the correct five-digit password to unlock or the
Master Password of 50865 to temporarily unlock the meter.

To remove the password go to the Advance menu and enter 0000 for the password.

Meter display flashes:

1. 99999

2. -9999

Check that the number of digits required for the scaled value does not exceed the
maximum digits for the display. If it does, try adjusting the decimal point location for less
precision or changing the PV display to the bottom display.

Display is unstable

Check:

1. Input signal stability and value.

2. Display scaling vs. input signal.

3. Increase the low gate setting in the Advance menu, this will allow more time to
average the input signal.

Display response is too slow

Check the low gate setting in the Advance menu.

Display reading is not accurate

Check:

1. Confirm the flowmeter K-Factor value

2. Check the input scaling

Display does not respond to input
changes, reading a fixed number

Check display assignment. It might be displaying max, min, or set point.

Display shows:
MAX, MIN, RATE, TOTAL,

or GTOT and a number

Display has been locked. Press Enter to unlock the display readings.
Relay operation is reversed

Check fail-safe settings in Output menu

Relays do not respond to signal

Check:

1. Relay action in Output menu

2. Set and reset points

3. Check manual control menu

If the display locks up or the meter
does not respond at all

Cycle the power to reboot the microprocessor.

CapTouch buttons do not respond

1. If hand-symbol is flashing, multiple buttons were touch at the same time, wait a few
seconds until the hand symbol goes off.

2. If Delayed mode has been set, press & hold any button for 5 seconds, the buttons
should respond normally.

3. If the slide switch on the display module is in the Lock position, move the switch to
the Unlock position; see Turning Off CapTouch Buttons on page 39.

Total and/or Grand Total do not
reset

Check:

1. Total / Grand Total not password protected

2. Grand Total set to non-resettable (this cannot be overridden)

3. Total / Grand Total manual reset disabled. Check Advanced Total and Grand Total
reset settings and Enable manual reset.

Other symptoms not described
above

Call Technical Support for assistance.

PD6938 Pulse Input Flow/Rate Totalizer

Instruction Manual

PRECISION DIGITAL CORPORATION

233 South Street • Hopkinton MA 01748 USA
Tel [phone] • [phone]

www.predig.com

LIM6938HA_A

SFT133 Ver 1.000 & up

07/23

Contact Precision Digital

Technical Support

Call: [phone] or [phone]
Email: [email protected]

Sales Support

Call: [phone] or [phone]
Email: [email protected]

Place Orders

Email: [email protected]

For the latest version of this manual please visit

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