Measurement DBK65 User Manual

DBK65 8-Channel Transducer Interface Module

D

The DBK65 is campatible with: WaveBook, ZonicBook, LogBook, DaqBook, DaqLab, DaqScan, and DaqBoard/2000 Series devices.

Overview …… 1
DBK65 Power Requirements …… 2
Power Available for Transducers …… 2

DBK65 Voltage Regulation ...... 2

Selecting an Excitation Voltage …… 3
Customizing a Voltage …… 4
Creating a 4 to 20mA Current Loop …… 5
Source Impedance and Settling Time ….. 6
Configuring the DBK65 Address …… 7
Configuring the Primary Data Acquisition Device …… 8
Connecting the DBK65 to Signals and to the Primary Data Acquisition Device …… 9
Software Setup …… 10
Calibrating a Transducer using the “Shunt Calibration” Technique …… 11
DBK65 Specifications …… 12

Overview

The DBK65 is an 8 channel transducer
interface module. Transducers of 2, 3, 4,
and 6 wire type can be easily connected
to the device by means of removable
screw terminal blocks, 1 per channel.

The module is ideally suited for
transducer outputs of the following
types. Wiring schematics are provided
on page 2 of this DBK65 section.

• 4 to 20 mA

• 3-wire string pots

• 4-wire bridge based transducers

• 6-wire bridge based transducers

BK65

DBK65 Block Diagram

Note 1: The user can install a resistor for use with the programmable regulator. The programmable voltage source can be

Note 2: The user can install a 250Ω resistor across the positive and negative signal lines (+Signal and -Signal) for

within the range of 5 to 20 VDC.

4 to 20 mA transducer outputs.

DBK Option Cards and Modules 987693 DBK65 pg. 1

Each of the 8 channels can be set for a different excitation voltage. 5, 10, 15, and 24 VDC are provided
internally from the DBK65 and are selected via placement of a jumper. In addition, a fifth jumper position
can be used to select a custom voltage between 5 and 20 VDC. The user must install a resistor if this
option is desired. The following section, Customizing a Voltage, contains additional information.

Each channel includes 2 screw terminals that allow for a relay closure. Designated as CAL+ and
CAL-, the terminals can be used to switch in a calibration resistor for 6-wire transducers. Note that the
DBK65’s rear panel CAL switch will open or close the internal calibration switches for all 8 channels
simultaneously.

DBK65 Power Requirements

The amount of DC power required, which is supplied to the DBK65 through its Power-In DIN5 connector,
is 15 V @ 833 mA, 20 V @ 625 mA, assuming max load. In addition, the amount of power drawn from
the P1-based host acquisition device, such as a Daq device or a LogBook is 25 mA from ±15 V, 750 mW
total. For purpose of our discussion here, a P1-based device is one which is connecting to the DBK65 via
the DB37 (P1) connector.

Power Available for Transducers

At the excitation voltages available from the DBK65 (5 to 24 V) a single transducer will typically d raw
from 10 to 100mA. This fact and the per-channel and per-module current limits must be taken into account
to avoid overloading the system.

• Total current available, for all 8 channels: 240mA.

• Current available for a single channel: 100mA.

• Transducer, typical current draw: 10 to 100mA

DBK65 Voltage Regulation

Better voltage regulation results in a lower variance of the source output voltage [excitation voltage], as
load is applied. Graphs depicting DBK65 voltage regulation for excitation set at 5, 10, 15, and 24 V are
included with the product’s specifications.

The following graph is intended to provide a better understanding of voltage regulation. In the graph, the
output voltage (V
This also applies to the user settable 5 to 20 VDC.

The ±5% variance factor holds true up to the limiting current (Max Current). Refer to the graphs at the end
of Specifications for typical voltage and current values.

) exhibits less than ±5% variance from nominal voltage, i.e., 5, 10, 15, or 24 VDC.

Out

Typical Current Limiting Voltage Curve

DBK65 pg. 2 987693 DBK Option Cards and Modules

Selecting an Excitation Voltage

Each channel has a voltage select header, which consists of 5 pairs of pins and a jumper. The jumper
position determines the excitation voltage. Possible voltages are 5, 10, 1 5, and 24 VDC. A fifth possibility
exists for a custom voltage that resides within the range of 5 to 20 V. To obtain a custom voltage you must
install a resistor in the excitation line labeled “PGM.” The method is discussed shortly.

Reference for Selecting a Pre-Set Voltage Value

The discharge of static electricity can damage some electronic components.
Semiconductor devices are especially susceptible to ESD damage. You should
always handle components carefully, and you should never touch connector pins or
circuit components unless you are following ESD guidelines in an appropriate ESD­controlled area. Such guidelines include the use of properly grounded mats and
wrist straps, ESD bags and cartons, and related procedures.

WARNING

To select a pre-set voltage (5, 10, 15, or 24V):

HOT COMPONENTS! Allow the DBK65 module to cool for at least 30 minutes
before removing the top cover. Some internal components can become very hot
and may cause burns.

1. Remove the DBK65 from power and disconnect all signal lines.

2. Allow the unit to cool for at least 30 minutes.

3. Remove the 4 screws from the top cover plate. Then remove the plate.

4. Position the voltage select header’s jumper to the desired setting. See the preceding figure.

5. Re-install the top cover plate and secure it with the 4 screws that were removed in step 3.

DBK Option Cards and Modules 987693 DBK65 pg. 3

Customizing a Voltage

To make use of the custom voltage feature you will need to acquire a resistor of the calculated value. The
formula to use is:

= (V

R

2

Example:

Suppose you wanted an excitation source of 12V. Simply replace the V
R

. Thus, R2 = (12 - 1.2) / 0.007645 = 1412.688Ω Ιn practice, a 1400 ohm, 1% resistor would be used.

2

Of course, 1400Ω is a little off from the 1412.688Ω, which was calculated. To see the actual nominal
voltage that would result from 1400Ω we can use a second equation.

V

out

V

out

After the resistor value is known, it can be installed as follows.

– 1.2V) / 0.007645

out

= 1.2V (1 + R2/158) + 0.00005*R

= 1.2 (1 + 1400/158) + 0.00005*1400 = 11.903 volts

The discharge of static electricity can damage some electronic components.
Semiconductor devices are especially susceptible to ESD damage. You should
always handle components carefully, and you should never touch connector pins or
circuit components unless you are following ESD guidelines in an appropriate ESD­controlled area. Such guidelines include the use of properly grounded mats and
wrist straps, ESD bags and cartons, and related procedures.

variable with 12V and solve for

out

2

WARNING

1. Remove the DBK65 from power and disconnect all

signal lines.

2. Allow the unit to cool for at least 30 minutes.

3. Remove the 4 screws from the top cover plate. Then

remove the plate.

4. Remove solder from the 2 holes at the resistor mounting

location.

5. Using rosin core solder and proper soldering technique,

solder the resistor into position for the applicable
channel. Be sure that the resistor leads are short

enough to avoid making contact with the metal
chassis.

The figure to the right indicates the resistor location for
use with channel 0 (CH00). The location scenario is similar
for all 8 channels.

Refer to the following table for a channel’s PGM Resistor Location
number. The location numbers appear on the circuit board.

HOT COMPONENTS! Allow the DBK65 module to cool for at least 30 minutes
before removing the top cover. Some internal components can become very hot
and may cause burns.

DBK65 pg. 4 987693 DBK Option Cards and Modules

Channel PGM Resistor

Location

CH00 R110 J11
CH01 R120 J21
CH02 R130 J31
CH03 R140 J41
CH04 R150 J51
CH05 R160 J61
CH06 R170 J71
CH07 R180 J81

6. On the jumper header, reposition the channel’s voltage out jumper to the “PGM” position. Refer to

the table for a channel’s applicable Jumper Header. The header numbers appear on the circuit board.

7. If applicable, install resistors for other channels, and set the applicable voltage out jumper headers to

PGM.

8. Re-install the top cover plate and secure it with the 4 screws that were removed in step 3.

Creating a 4 to 20mA Current Loop

Voltage Out

Jumper Header

Voltage

Set

V

out

Resistor

Value

R

2

Inputs to monitor the commonly used 4 to 20mA current loops most often employ a 250Ω precision
resistor to develop a 1 to 5 VDC voltage drop.

Ideally, a resistor for such purpose should have a 0.1% tolerance (or better) with a minimum power rating
of 0.25W and a temperature coefficient of at least 25ppm/°C.

Lower values of resistance, for example, 62.5Ω [for a lower voltage drop within the loop of 0.25 to 1.25
VDC] will require that the host data acquisition device use a gain o f x4 to maximize the signal resolution.

The discharge of static electricity can damage some electronic components.
Semiconductor devices are especially susceptible to ESD damage. You should
always handle components carefully, and you should never touch connector pins or
circuit components unless you are following ESD guidelines in an appropriate ESD­controlled area. Such guidelines include the use of properly grounded mats and
wrist straps, ESD bags and cartons, and related procedures.

WARNING

To create a 4 to 20mA current loop:

HOT COMPONENTS! Allow the DBK65 module to cool for at least 30 minutes
before removing the top cover. Some internal components can become very hot
and may cause burns.

1. Remove the DBK65 from power and disconnect all signal lines.

2. Allow the unit to cool for at least 30 minutes.

3. Remove the 4 screws from the top cover plate. Then remove the plate.

4. Remove solder from the 2 holes at the resistor mounting location (see the following figure for

location).

DBK Option Cards and Modules 987693 DBK65 pg. 5