Dwyer Instruments AVUL Operating Manual

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Bulletin P-AVUL-M

3-3/16

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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

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

Factory calibration certicate

NIST

NIST certicate

GLD

Electrical cable gland

RTU/ASCII

3-49/64

[95.71]

3-33/64

[89.13]

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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7-41/64

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Ø15/32

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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: 219/879-8000

Fax: 219/872-9057

www.dwyer-inst.com

e-mail: info@dwyermail.com

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

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 OFF OFF

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

/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 OFF OFF

OFF

FPM m/s m/s m/s

CFM

/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

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.

Security Level Setting

0 1 2 3

Access View Menu Edit Menu Span Zero

000 111 222 333

Yes Yes No No

Yes No No No

Yes Yes No No

Table 3: Security Settings

Mode Selection / Digital Dampening Menu

From the home display, pressing the span and zero button simultaneously for 3 seconds will access the Menu Security Level. If the level is set to 0 or 1, pressing and holding the span button for 3 seconds, a second time, will access the Mode Selection Menu. The display will default to air velocity when rst powered up. Pressing the zero button will cycle to air ow.

Once the desired mode is displayed, pressing and holding the span button for 3 seconds will save the selected mode and display the digital dampening or averaging parameter. This parameter stabilizes the output and the display by averaging the readings. There are 2.5 readings taken each second and the user can select the number of seconds that they would like to average, up to 240 seconds. The display and the output will continue to update at a rate of 2.5 updates per second, but the moving average is used for these updates.

Velocity Mode

K-Factor Adjustment

If the Velocity Mode was selected, pressing and holding the span after adjusting the digital dampening will enter the Velocity Mode and the transmitter will display the engineering unit that has been selected by the DIP switch. Pressing and holding the span button for 3 seconds will enter the K – Factor adjustment. The K – Factor can be adjusted between 0.001 to 9.999. The K-Factor can be adjusted by pressing the span button to select the digit and pressing the zero button to increment the value of the digit. Pressing and holding the span button for 3 seconds will enter the Maximum Output Adjustment parameter.

Flow Mode K-Factor Adjustment

If the Flow Mode was selected, pressing and holding the span after adjusting the digital dampening will enter the Flow Mode and the transmitter will display the engineering unit that has been selected by the DIP switch. Pressing and holding the span button for 3 seconds will enter the K–Factor adjustment. The K–Factor can be adjusted between

0.001 to 9.999. The K-Factor can be adjusted by pressing the span button to select the digit and pressing the zero button to increment the value of the digit. Pressing and holding the span button for 3 seconds will enter the Area Adjustment parameter.

Area Adjustment

For ow applications, the area is multiplied by the velocity to determine the volumetric air ow. The area will be listed in either CFM or m

/h depending on the DIP switch settings. The units will appear on the display at the time of adjustment. The area can be adjusted by pressing the span button to select the digit and pressing the zero button to increment the value of the digit. Pressing and holding the span button for 3 seconds will enter the Maximum Output Adjustment parameter.

Maximum Output Adjustment

The maximum output can be equivalent to air velocity or air ow. After adjusting the K-Factor, the display will indicate if the adjustment is set for velocity or air ow. Pressing the zero button will toggle between the selections. Pressing and holding the span button for 3 seconds will enter the maximum output adjustment. The maximum output can be adjusted by pressing the span button to select the digit and pressing the zero button to increment the value of the digit. Pressing and holding the span button for 3 seconds will save this value and go to the Security Update Menu.

Security Update / Save Changes Menu

The Security Update Menu allows the security level to be set either higher or lower than the current security level setting. This security level will be displayed the next time the Menus are accessed from the home screen. Pressing the zero button cycles through the security levels. Pressing and holding the span button for 3 seconds accepts the new security level and gives the option to save all the menu changes. Pressing the zero button will toggle between yes and no. Yes will save the changes made to all menu items and no will discard all the changes made to all menu items. If the display is set to yes, pressing and holding the span will save the menu items and return the display to the home position.

FACTORY DEFAULT PROCEDURE

In order to reset all of the menu settings back to their factory programmed values, press and hold both the span and zero buttons simultaneously for 10 seconds until FACt is displayed on the LCD. Upon releasing the buttons, the unit will be factory defaulted. Since resetting the transmitter will wipe out all changes, it is necessary to zero (and possibly span) the transmitter before taking measurements.

MAINTENANCE/REPAIR

Upon nal installation of the Series AVUL Air Velocity Transmitter, no routine maintenance is required besides zeroing the transmitter occasionally. Besides routine calibration and installation of the LCD, the Series AVUL is not eld serviceable, and it is not possible to repair the unit. Field repair should not be attempted and may void warranty.

WARRANTY/RETURN

Refer to “Terms and Conditions of Sales” in our catalog and on our website. Contact customer service to receive a Return Goods Authorization number before shipping the product back for repair. Be sure to include a brief description of the problem plus any additional application notes.

APPENDIX I: Air Velocity / Air Flow Calculations

Velocity in m/s is then calculated from the equation:

Velocity (m/s) = Velocity (FPM) x 0.00508

Flow in m Flow (CFM) = Area (ft Flow (m

/h is then calculated using the below equation:

/h) = Flow (CFM) x 1.6992

) x K-Factor x Velocity (FPM)

APPENDIX II: Maximum Flow

Max Flow Max K Factor x Area CFM m

/h CFM Range m3/h Range

5885000 9999000 1471.25 138.875

Table 4: Maximum Flow Values

APPENDIX III: Modbus

NOTICE

Communication Protocol Operation

Wiring should comply with Electrical Characteristics of Generators and Receivers for Use in Balanced Digital Multipoint

Systems, TIA/EIA-485-A-1998, Telecommunications Industry Association, 1998.

NOTICE

Wiring should comply with Modbus® Communication Protocol over Serial Line Specication and Implementation Guide V1.02,

Modbus Organization, Inc., 2006

NOTICE

Communications wiring must be in a daisy-chain fashion. Star connections are not permitted.

NOTICE

Cable shield must be connected to earth ground at one location only.

Figure 7 shows how to connect the AVUL in a network containing a common power supply. Use a cable containing two twisted pairs. One pair is to be used for D1(+) and D0(-). The other pair is to be used for power and common. This conguration is not suitable for AC supplies. Use a DC supply only. Care should be taken that there are not too many devices powered from the same supply as voltage drops will occur in the wiring. If you have many devices, or have long cable runs, the local supply conguration may be a better choice.

Figure 8 shows how to connect the AVUL in a network containing individual local supplies. Use a cable containing a twisted pair and a single conductor. The pair is to be used for D1(+) and D0(-). The single conductor is to be used for common. Both AC and DC supplies are suitable for this conguration.

In either conguration you must use shielded cable. The AVUL has a shield terminal for a convenient location to make connections. It is not electrically connected to the AVUL. Connect the shield to earth ground at one location only to prevent ground loops.

All devices in the network should be daisy chained. Star connections and T connections are not permitted.

The D1(+) and D0(-) lines must be terminated at both ends with a 120 ohm resistor. If the AVUL is an end device it has an on-board resistor that may be used. See Modbus® Communication Protocol DIP Switch Settings to enable it.

The network must be biased properly. If needed, there are bias resistors on-board the AVUL. No more than two sets of bias resistors should be enabled in the network. See

Communication Protocol DIP Switch Settings to enable them.

Modbus

PWR GND IOUT VOUT

D1(+) D0(-)COM

D1(+)

D1(+) D0(-)

COM

SUPPLY

PWR GND IOUT VOUT D1(+) D0(-) COM

KEY:

DEVICE

D1(+)

D0(-) PWR COM

DEVICE

D1(+) D0(-) PWR COM

APPENDIX IV: Programming Via Modbus

Communication Protocol

Modbus® Mode Supported Baud Rates Data Size Parity Stop Bits

RTU 9600

19200

8 Even

38400 57600

ASCII 7 Even

76800 115200

Odd

None None 2

Odd

None 2

Table 6: Supported Modbus

Communication Protocol Congurations

Figure 7

Common Power Supply

D0(-)

COM

+ -

POWER

Figure 8

Local Power Supply

Modbus® Communication Protocol DIP Switch Settings

Use the middle DIP Switch SW2 to congure the Modbus

Communication Protocol address of the device. The LCD will show the address when the transmitter is powered on. Valid addresses range from 1 to 247. By default, the device is shipped with the address 127 (as shown in Figure 10). A valid and unused address should be set before connecting to an existing network. However, the address can be changed while the device is operational. If the address is changed, the device will stop responding to the currently congured address immediately. The device waits 15 seconds after the last switch change before applying the new address. The device will not function properly if an invalid address is set. The red LED will periodically blink once indicating an invalid address. The LCD will display A Err when the transmitter is powered on if the address is invalid. See Appendix V for setting the Modbus

Communication Protocol address of the device. Use the right DIP Switch SW3 to congure other hardware and software options.

SW2

BIAS

RESISTOR

128 - MSB

AUTO SERIAL CONFIGURATION

TERMINATING RESISTOR

64 16

8 2

1 - LSB

Figure 9

Intelligent Serial Conguration

Intelligent serial conguration enables the device to determine the baud rate, data size, party, stop bits and even the Modbus from the serial trafc. This allows the Series AVUL to be quickly and easily deployed after a valid Modbus

Communication Protocol address is chosen.

To activate intelligent serial conguration, set a valid Modbus

Communication Protocol mode directly

Communication Protocol address using the left DIP switch SW2, connect the serial bus and power wires, and then apply power. The device will power up and begin examining the serial bus for communication. The Red LED will repeatedly ash twice, indicating that intelligent serial conguration is in progress.

If the device is setup ofine or away from the main network, it is necessary to generate Modbus communication. Attempting to read input registers is a good method to generate

Modbus

Communication Protocol trafc in order to congure the serial

Communication Protocol trafc. Note that while serial conguration is in progress, the device may not respond to requests. The device may require multiple read requests to complete the serial conguration process.

The intelligent serial conguration process will complete once a message addressed to the device is received and processed successfully. The serial conguration parameters are then saved to non-volatile storage and loaded by default each time the device starts. If the serial conguration of the bus changes, a power cycle of the device is required to restart the Intelligent Serial Conguration process.

Function Name Function Code

Read Coils Read Holding Registers Read Input Registers Write Single Coil Write Single Register Write Multiple Registers

Table 7: Supported Modbus

01 03 04 05 06 16

Communication Protocol Functions

The String data type is read as a stream of ASCII characters, with the rst character sent in the MSB of the rst register, and the second character sent in the LSB of the rst register and so on. If the string is shorter than the allotted size, the remaining bytes will be zero padded.

Multi-

Address

0001 – 0002

0003 – 0004

Velocity

Flow Area (ft2)

Velocity

Flow Area (m2) Description

Float

Data Type

0.01…999.99

0.00093…92.9

Value

0.01…999.99

0.00093…92.9

Range

Supported

Yes

Multi-

Address

Supported

Table 8: Holding Registers

Switch On Off

1-2 – Display Units Selection 3-4 – Reserved 5 - Intelligent Serial Conguration 6 – D1(+) Network resistor 7 – D0(-) Network resistor 8 – Terminating resistor

Enabled

511Ω Pull-up to 5V 511Ω Pull-down to GND 120Ω between D0(-) and D1(+)

Disabled

Pull-up not connected Pull-down not

connected

Open

Table 5: DIP Switch SW3 Functions

1 - The serial conguration, no parity with one stop bit is not ofcially supported by the

Communication Protocol standard. However, if this conguration is desired,

Modbus set switch 5 on DIP switch SW3 to off. The device will congure itself in Modbus

RTU

Communication Protocol mode with a data size of 8, no parity, and 1 stop bit. The baud rate will still be determined automatically.

Coils

The coil registers represent functions of the device. The value returned when reading a coil register indicates the status of the last function execution. If the value is 1, then the last time the function executed was a success. If the value is 0, then the function has either not been executed since power on or failed during the last execution. To execute a function, write 1 to the corresponding register. A response will be returned immediately and the value of the coil will be set to 0. Once the function completes, the value of the coil will be set to 1 if the operation was a success. An application should poll the value of the coil periodically during this time to determine if the function succeeded. If the coil value does not transition to 1 after at most 10 seconds, then the operation failed.

Multi-

Address

0001 0002 0003 0004

Perform Zero Function Perform Span Function Reset Factory Defaults Reset Device

Boolean Boolean Boolean Boolean

0…1 0…1 0…1 0…1

False – True False – True False – True False – True

Supported

No No No No

Table 9: Coils

Coil 1 – Zero Function

The zero function will attempt to recalibrate the zero point. This may be needed if the sensor has drifted over time. Note that the zero function will only re-zero the sensor if the current air velocity is within ±2% of span air velocity of the previous zero. If the current air velocity is outside the valid band, the zero function will fail and the coil value will remain 0. If the sensor has drifted far enough that the zero function fails, then the unit will have to be placed in ow to bring the current air velocity closer to the current zero, and the zero function will have to be executed multiple times until the actual zero is reached.

Coil 2 – Span Function

The span function will attempt to recalibrate the maximum air velocity. Note that accurate span air velocity depends on an accurate zero air velocity. The span function will fail if the zero function has not been executed within the last 5 minutes.

Coil 3 – Reset factory Defaults Function

The reset factory defaults function resets the zero, span, Velocity K value, Area, and Use Default K Value variables back to their factory default values.

Coil 4 – Reset Device Function

The reset device function allows this device to be reset remotely from the Modbus Communication Protocol. When the reset device function coil is written with a value of 1, the device will immediately respond with success. The reset will take place approximately 5 seconds after the command was received. Writing the value 0 to this coil has no effect.

Multi-address Support

Multi-Address support allows a register to be read or written to using different byte orientations specied by the address range. For example, input register 0003 can also be read at 2003, 4003 and 6003 with different byte orientations as listed in Table 10. Registers that do not have multi-address support are only available in Big-Endian byte orientation (Modbus

Communication Protocol standard).

Float/32 Bit Values 16 Bit Values Register 1 Register 2 Register 1

Byte Order Address Range MSB LSB MSB LSB

Big-Endian Byte Swap Word Sway Little-Endian

1 – 2000 2001 – 4000 4001 – 6000 6001 - 8000

Table 10: Multi-Address Support

APPENDIX V: Setting Modbus

Communication Protocol MAC Address of Unit

Switch Position 1 2 3 4 5 6 7 8

Address Value 128 64 32 16 8 4 2 1

Table 11: Device Objects

The address assignment is determined by adding the values for each of the switches that are in the ON position. The transmitter comes from the factory with all of the DIP switches, except position 1, in the ON position as shown in Figure 10. The address of the transmitter would be 127 as it would be 64+32+16+8+4+2+1 = 127. Another example would be if the address desired was 008, the only DIP switch position in the ON position would be position 5 as shown in Figure 11

12345678

Figure 10

Figure 11

NOTICE

possible address would be address 255 when all of the DIP switches were set to ON, but the transmitter only has valid address from 1 to 247. Any address outside of this range will give an error code.

APPENDIX VI: Modbus

0001

0002

0003

0004

0005

0006

0007 – 0008 0009 – 0010 0011 – 0012 0013 – 0014 0015 – 0016 0017 – 0018 0019

0020 – 0021

8001 – 8006 8007 – 8012 8013 – 8018 8019 – 8024

Though the minimum possible address would be address 0 when all the DIP switch positions were set to OFF, and the maximum

Communication Protocol Registers

Velocity (FPM)

Velocity (0.001 MPS)

Flow (CFM)

Flow (CMH)

Temperature (0.1 °F)

Temperature (0.1 °C)

Velocity (FPM)

Velocity (MPS)

Flow (CFM)

Flow (CMH)

Temperature (°F)

Temperature (°C)

Sensor Operational

Sensor Communication

Errors

Application

Modbus Firmware Version Sensor Application Firmware Version

Application

Modbus Serial Number Sensor Application Serial Number

Table 12: Modbus

Signed 16bit

integer

Signed 16bit

integer

Signed 16bit

integer

Signed 16bit

integer

Signed 16bit

integer

Signed 16bit

integer

Float

Unsigned 16bit

integer

Unsigned 32bit

integer

0…1

0…2

String

Communication Protocol Registers

False –

True

-1

0…2321

Multi-

Address Supported

Yes

APPENDIX III: Menu Flow Chart

BUTTON PRESS LEGEND

MENU CONVENTIONS

ZERO

SPAN

ZERO

SPAN

ZERO

SPAN

Averaging Menu

= PRESS ZERO BUTTON

= PRESS SPAN BUTTON

= PRESS AND HOLD ZERO BUTTON

= PRESS AND HOLD SPAN BUTTON

= PRESS AND HOLD ZERO AND SPAN BUTTONS

SECURITY LEVEL SELECTION

IN HOME POSITION:

CALIBRATE UNIT TO ZERO PRESSURE.

ZERO

CALIBRATE UNIT TO SPAN PRESSURE.

SPAN

ZERO

ENTER MENU DISPLAY

SPAN

IN MENU DISPLAY:

SEQUENCES TO NEXT MAIN MENU ITEM, AND IF A MENU ITEM IS CHANGED TEMPORARILY SAVES THE SELECTION

SPAN

SEQUENCES THROUGH SUB MENU SELECTIONS OR INCREMENTS DIGITS

ZERO

SEQUENCE TO NEXT DIGIT. ACTIVE DIGIT WILL BLINK.

SPAN

HOME POSITION

ZERO

SPAN

WHILE BUTTONS ARE PRESSED

WHEN BUTTONS ARE RELEASED DISPLAYS CURRENT SECURITY LEVEL

ZERO

TO CHANGE SECURITY LEVEL

SPAN SPAN

IF SECURITY IS SET TO 0, 1, OR 2

ZERO

SPAN

IF SECURITY IS SET TO 3

DISPLAY IS NOT NECESSARY

FACTORY SETTINGS HOLD 7 SECONDSTO HOME POSITION

RESTORED, THEN RE TURNS

ZERO

SPAN

INCREMENT DIGIT

SELECT DIGIT

SECURITY LEVEL SETTING

0000 1111 2222 3333

HOME POSITION

= BLINKING DIGIT

USE DEFAULT DIP SWITCH SETTINGS

MODE SELECTION VELOCITY OR FLOW

ADJUST AVERAGING

TO "VELOCITY OR FLOW" MENUS

PRESS ANY KEY OR WAIT 5 SECONDS

ZERO SPAN

ZEROSPAN

ZERO

BLINKING UNITS AS

ZEROSPAN

SELECTED BY DIP SWITCHES

SPAN

INCREMENT

ZERO

DIGIT

SELECT

AVG

SPAN

DIGIT

SPAN

FROM AVERAGING MENU

Velocity Mode Menu

SPAN

ADJUST DISPLAY K FACTOR

SELECT MAXIMUM OUTPUT SET BY PRESSURE OR VELOCITY

ADJUST VELOCITY OUTPUT HIGH

TO "UPDATE SECURITY AND SAVE" MENU

UPON RELEASE

SPAN

SPAN UPON RELEASE

SPAN

FPM

FPM OR M/S BASED ON DIP SWITCH SETTING

M/S

SPAN

ZERO

SPAN

ZERO

SPAN

INCREMEN DIGIT

SELECT DIGIT

INCREMEN DIGIT

SELECT DIGIT

FROM AVERAGING MENU

SPAN

ADJUST DISPLAY K FACTOR

SPAN

UPON RELEASE

SPAN UPON RELEASE

SPAN

SPAN UPON RELEASE

SPAN

TO "UPDATE SECURITY AND SAVE" MENU

INCREMEN

SELECT

ZERO

SPAN

DIGIT

INCREMEN

SELECT

ZERO

SPAN

DIGIT

ON DIP SWITCH SETTING

FPM OR M/S BASED

ADJUST FLOW OUTPUT HIGH

CFM

M /H

INCREMEN

SELECT

ZERO

SPAN

DIGIT

FAREA

SQ. FEET OR SQ. METERS BASED ON DIP SWITCH SETTING

MAREA

SPAN UPON RELEASE

SPAN

SELECT MAXIMUM OUTPUT SET BY PRESSURE OR FLOW

Flow Mode Menu

FROM "UPDATE SECURITY

Security Menu

UPDATE SECURITY LEVEL

AND SAVE" MENU

ZERO ZERO ZERO

ZERO

SPAN SPAN SPAN SPAN

SAVE CHANGES

SPAN UPON RELEASE ZERO

ZERO

SPANSPAN

HOME POSITION

NOTES

__________________________________________________________________________________________________________________________________________

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

Phone: 219/879-8000

Fax: 219/872-9057

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e-mail: info@dwyermail.com

Dwyer Instruments AVUL Operating Manual

Specifications and Main Features

Frequently Asked Questions

User Manual