Dwyer Instruments AVUL Operating Manual

Bulletin P-AVUL-M

3-3/16

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24.58

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®

Series AVUL Air Velocity Transmitter with Modbus® Communication

Specications - Installation and Operating Instructions

The SERIES AVUL Air Velocity Transmitter quickly and accurately measures air

velocity or volumetric ow in imperial or metric units. Simultaneous current and
voltage outputs on all models provide universal inputs to monitoring equipment while
the output range, units, and 0 to 5/10 VDC output can be congured via local DIP
switches. The optional integral display, or the portable remote display tool, provide a
convenient way to locally monitor process values and congure the unit.

Models are available in 3% and 5% accuracy models to suit a variety of needs, and the
optional BACnet MS/TP or Modbus
to be daisy-chained while providing access to all of the velocity and ow data, as well
as additional information such as air temperature.

MODEL CHART

Model AVUL -3 D A1 -LCD AVUL-3DA1-LCD
Accuracy 5

3

Mounting D Duct mount
Output A1

Options LCD

®

RTU/ASCII communication protocol allows units

±(0.2 m/s + 5% of reading) @ standard

conditions

±(0.2 m/s + 3% of reading) @ standard

conditions

Analog universal (0 to 5 VDC, 0 to 10 VDC,

B1
M1

4 to 20 mA)
Analog + BACnet MS/TP
Analog + Modbus

LCD display

FC

Factory calibration certicate

NIST

NIST certicate

GLD

Electrical cable gland

®

RTU/ASCII

3-49/64

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SPECIFICATIONS

Service: Clean air and non-combustible, compatible gases.
Wetted Materials: Consult Factory.

Range: 1000, 2000, 3000, 4000 FPM (5, 10, 15, 20 m/s); Field selectable.

Accuracy: ±(5% of reading + 0.2 m/s) or ±(3% of reading + 0.2 m/s) @ standard
conditions, depending on model.

Temperature Limits: 32 to 122°F (0 to 50°C).
Power Requirements: 24 VDC ±20% or 24 VAC ±20%.
Humidity Limits: 5 to 95% RH, non-condensing.

Output Signals: 4 to 20 mA, 0 to 5 VDC, 0 to 10 VDC .

Response Time (90%): 10 seconds, typical.
Zero & Span Adjustments: Digital push buttons.

Output Load Resistance: Current Output: 0 to 1100 Ω max.; Voltage Output:
Minimum load resistance 1 kΩ.

Current Consumption: 60 mA Max.
Display (optional): 5 Digit LCD.

Electrical Connections (Analog): Power and output: four wire removable
European style terminal block for 16 to 26 AWG.
Communication (optional): Connections: BACnet MS/TP or Modbus
three wire removable European style terminal block for 16 to 26 AWG; Supported
Baud Rates: 9600, 19200, 38400, 57600, 76800, 115200.

Device Load: 1/8th unit load.
Electrical Entry: 1/2˝ NPS thread. Accessory (A-151): Cable gland for 5 to 10 mm

diameter cable.

Enclosure Rating: NEMA 4X (IP66).
Mounting Orientation: Flow direction must be parallel to the sensor tip;

See Installation section for details.

Weight: 6.0 oz (160 g).
Agency Approval: CE, RoHS.

1/2 NPS

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®

RTU/ASCII:

2-5/32
[54.82]

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46360, U.S.A.

Phone: [phone]

Fax: [phone]

www.dwyer-inst.com

e-mail: [e-mail]

INSTALLATION

Duct Mount:

The transmitter should be mounted away from fans, corners, heating and cooling
coils, and other equipment that will effect the measurement of the air velocity. It
is recommended that the AVUL is mounted 10 duct diameters downstream of any
disturbances and 5 duct diameters upstream of any disturbances, if possible.

1. Mark and drill a 0.750-0.938˝ (20-24 mm) diameter hole into the duct.

2. Insert and center the duct mount ange in the previously drilled hole and mark
location of the three mounting screw holes.

3. Remove the mounting ange and drill or punch the mounting holes in the marked
locations.

4. Fasten the ange to the duct using three #8 x 1/2 pan head sheet metal screws. Do
not over tighten screws.

5. Insert the AVUL probe into the ducts mount ange and set the desired insertion
depth.

6. Note the ow direction and unit alignment as shown on sensor tip and product label,
tighten probe retention set screw on the duct mount ange screw to afx the probe in
place.

Electrical Connection:

The Series AVUL is powered and simultaneously transmits a two-wire 4 to 20 mA
current output and a three-wire 0 to 5 VDC or 0 to 10 VDC voltage output via a
removable four conductor terminal block. The transmitter power supply common is
used to reference the current and voltage outputs so either current, voltage, or current
and voltage may be wired according to the application. The range of the voltage output
can be selected using the on board DIP switches as described in the Analog DIP
Switch Settings section of this manual.

Power Supply

Choose a power supply with a voltage and current rating sufcient to meet the power
specications under all operating conditions. If the power supply is unregulated, make
sure the output voltage remains within the required voltage range under all power line
conditions. Ripple on the supply should not exceed 100 mV.

Although low loop resistances are recommended, the absolute maximum current loop
load resistance, R

R

MAX = (VPS – 2.0) / 0.02 where VPS is the power supply voltage

For a 24 VDC nominal power supply, this evaluates to R

MAX , is dened by the following the equation:

MAX = 1100 ohms.

Shielded two wire cable is recommended for current output loop wiring. Ground the
shield at the power supply end only.

The maximum length of connecting wire between the current transmitter and the
receiver is a function of wire size and receiver resistance. That portion of the total
current loop resistance represented by the resistance of the connecting wires
themselves should not exceed 10% of the receiver resistance. For extremely long
runs (over 1,000 ft.), it is desirable to select receivers with higher resistances in order
to keep the size and cost of the connecting leads as low as possible. In installations
where the connecting run is no more than 100 ft, connecting lead wire as small as No.
22 Ga. can be used.

Voltage Output Operation

CAUTION

DO NOT EXCEED SPECIFIED SUPPLY VOLTAGE RATINGS.
PERMANENT DAMAGE NOT COVERED BY WARRANTY WILL

RESULT.

The terminal block is removable, and each of the terminals are labeled underneath the
terminal block on the circuit board. The voltage output and the power supply must have
separate wire leads that are only joined at terminal 2 of the transmitter, as shown in
Figure 2. Additional error may occur for the voltage output if a single wire is used or if
the wires are joined at the power supply or receiver. The connections to the transmitter
are made to terminals 1, 2, and 4 (PWR, GND, and VOUT respectively) on the terminal
block as shown in Figure 4.

CAUTION

DO NOT EXCEED SPECIFIED SUPPLY VOLTAGE RATINGS.
PERMANENT DAMAGE NOT COVERED BY WARRANTY WILL

RESULT.

Current Output Operation

CAUTION

DO NOT EXCEED SPECIFIED SUPPLY VOLTAGE RATINGS.
PERMANENT DAMAGE NOT COVERED BY WARRANTY WILL

RESULT.

The terminal block is removable, and each of the terminals are labeled underneath
the terminal block on the circuit board. As the power supply and outputs share the
same common signal (GND), the outputs may have separate wires but must effectively
join at terminal 2 of the transmitter, as shown in Figure 1. The connections to the
transmitter are made to terminals 1, 2, and 3 (PWR, GND, and IOUT respectively) on
the terminal block as shown in Figure 4.

Figure 2

Voltage Output Wiring

The minimum receiver load is 1 kΩ. The resistance due to the wire should be low
compared to the receiver load resistance. While the voltage at the terminal block
remains unchanged with a 10 mA current ow, resistive losses in the wiring do cause
errors in the voltage delivered to the receiver. For a 1% accurate gauge, the resistance
of the wires should be less than 0.1% of the value of the receiver load resistance. This
will keep the error caused by the current ow below 0.1%.

The output across VOUT and COM will be either 0 to 5 VDC, 0 to 10 VDC, or the
inverse depending on the DIP switch setting. See the Analog DIP Switch Settings
section for more information.

Figure 1

Current Output Wiring

Simultaneous Current and Voltage Output Operation

RANGE

CAUTION

DO NOT EXCEED SPECIFIED SUPPLY VOLTAGE RATINGS.
PERMANENT DAMAGE NOT COVERED BY WARRANTY WILL

RESULT.

The terminal block is removable, and each of the terminals are labeled underneath the
terminal block on the circuit board. The voltage output and the power supply must have
separate wire leads that are only joined at terminal 2 of the transmitter, as shown in
Figure 3. Additional error may occur for the voltage output if a single wire is used or if
the wires are joined at the power supply or receiver. The connections to the transmitter
are made to terminals 1, 2, 3 and 4 (PWR, GND, IOUT, and VOUT respectively) on
the terminal block as shown in Figure 4, which reects both the 4-20 mA and 0-5/10
VDC outputs in the same circuit. Details of each output are detailed in their electrical
connection sections.

Setting the Air Velocity Range

The range of the instrument is selected by using DIP switches 1 and 2 on SW1. Table
1 shows the maximum full scale value for the selected range and unit. Refer to Setting
the Engineering Units section for information on setting the unit.

DIP Switch SW1 Full Scale Range
1 2 Imperial (FPM) Metric (m/s)

ON

ON
ON
OFF
OFF

OFF

ON

OFF

4000
3000
2000
1000

20
15
10
5

Table 1: DIP Switch SW1 Settings for Full Scale Range

Setting the Engineering Units

The Series AVUL can be congured to indicate velocity in imperial (FPM, CFM) or
metric (m/s, m

3

/h) units using DIP switches 4 and 5 on SW1, and Table 2 shows the

values. The units will be displayed on the optional LCD display if connected.

DIP Switch SW1 Units
4 5 Velocity Mode Air Flow Mode

ON

ON
ON
OFF
OFF

OFF

ON

OFF

FPM
m/s
m/s
m/s

CFM

3

m

3

m

3

m

/h
/h
/h

Table 2: DIP Switch SW1 Settings for Units

The default operating mode is velocity, but changes can be made, such as ow
mode, via the menu system while an optional display or remote display accessory is
connected. Please refer to Appendix VI for a full menu ow chart.

Setting the Output Voltage Range

Voltage Output can be either 0 to 5 VDC or 0 to 10 VDC depending on the position of
DIP Switch 6 ON SW1.

Simultaneous Current and Voltage Output Wiring

Figure 3

ANALOG DIP SWITCH SETTINGS

The analog output DIP switches (SW1) are located above the terminal blocks on the
left are as shown in Figure 4. A small screw driver or pen can be used to change the
position of the switches as required.

WARNING

All power should be turned off to the transmitter before adjusting
the DIP switch settings to avoid electrical shock.

UNITS

5V

REV

10V
DIR

• When the switch is in the ON position, the output will be 0 to 10 VDC.

• When the switch is in the OFF position, the output will be 0 to 5 VDC.

Setting the Input / Output Action

The output will either follow the process directly (DIRECT) or inverted (REVERSED)
based on the position of DIP Switch 7 on SW1.

• When the switch is in the ON position, the output directly follows the input (i.e. output
increases as the input increases).

• When the switch is in the OFF position, the output acts in reverse of the input (i.e.
output decreases as the input increases).

Figure 4

Analog Dip Switches

Factory Default Settings (DIP SW1 – All Switches ON)

Range = Highest Range Setting (4000 FPM)
Units = Imperial (FPM)
Voltage Output Range = 0 to 10 VDC
Direct / Reverse Output Action = Direct

KEY

CALIBRATION

NOTICE

takes place. This delay is used to reduce vibration or disturbances of the user related
to the button presses.

There is a 5 second delay from the time the zero or span calibration
buttons are released until the time that the change in calibration

NOTICE

adjusted by the user.

Zero Calibration

The zero calibration can be set by covering the sensor to ensure no air ow and
pressing the zero button for 3 seconds. If either the remote or local LCD is present, the
display will read ZEro and then sequence back to the home display.

SPAN Calibration

The span calibration can be adjusted only after setting the zero adjustment. It must
be completed within 5 minutes of the last zero calibration. The span calibration button
will be ignored until the zero calibration is completed. Place the sensor in airow that
matches the maximum selected range of the transmitter. Press and hold the span
button for 3 seconds. If either the remote or local LCD is present, the display will read
SPAn and then sequence back to the home display. If the span calibration is attempted
before adjusting the zero calibration, the FAiL error message will be displayed briey
before returning to the home display.

LCD Display

The Series AVUL can be ordered with an optional, integral LCD. It comes with a
housing cover and overlay to protect the display. The display will plug into the pins as
shown in Figure 5. If the display is not needed for normal operation, the transmitter can
be ordered without the LCD.

The security level that is set in the Programming Menu section
of the manual will determine which calibrations, if any, may be

Figure 6

Remote Display Diagram

Display Error Messages

ovEr = The air velocity is greater than the maximum span value causing an Over

Range Error

UndEr = The air velocity is less than the minimum span value causing an Under Range

Error

FAiL = When the span or zero buttons are pressed, the air velocity value is out of the
range to allow a correct setting. This may be due to a sensor failure.
Err1 = The sensor is damaged.

Pluggable Display Diagram

Figure 5

Another option for models that do not have a display would be to use a Model A-435-A
remote display tool which can plug into the connector shown in Figure 6. The remote
display tool has two buttons that function identically to the buttons on the PCB.

PROGRAMMING MENUS

Home Menu

During normal operation, the display will be in the Home Menu and will display the
current measured pressure and the engineering units.

Menu Access Security

While in the Home Menu, press and hold the Zero and Span buttons simultaneously
until SECUr appears on the display in order to access the other programming menus.
Upon releasing the buttons, the display will indicate the current security level.

If the current security level is the security level desired (i.e. Security Level 0), press
and hold the span button for 3 seconds to enter the Velocity or Air Flow Menu.

If the security level is not the desired level, the security level can be changed
temporarily to a lower security level or permanently to a higher level of security by
pressing the zero button. A security code will appear on the display, and it can be
changed to one of the codes listed in Table 3. The span button chooses which digit
and the zero button increments the value of that digit. Pressing and holding the span
button will store the value.

The level of access to the programming menus and the calibration is limited based on
the security level. Table 3 details the level of access for each security level.