Fox Thermal FT3 User manual

Model FT3
Modbus
Fox Thermal
THERMAL MASS FLOW METER
& TEMPERATURE TRANSMITTER
Precision Mass Flow Measurement
An ON
I CON Brand
104985
Rev. D
www.foxthermal.com | 399 Reservation Road Marina, CA. 93933

This publication must be read in its entirety before performing any
operation. Failure to understand and follow these instructions could result
in serious personal injury and/or damage to the equipment. Should this
equipment require repair or adjustment beyond the procedures given herein,
contact the factory at:
FOX THERMAL INSTRUMENTS, INC.
399 RESERVATION ROAD
MARINA, CA 93933
TELEPHONE: [phone]
FAX: [phone]
EMAIL: [e-mail]
Download Technical Data Sheets from our website:
www.foxthermal.com
Fox Thermal believes that the information provided herein is accurate
however be advised that the information contained herein is NOT
a guarantee for satisfactory results. Specically, this information is
neither a warranty nor guarantee, expressed or implied, regarding
performance; merchantability; tness; or any other matter with
respect to the products; nor recommendation for the use of the
product/process information in conict with any patent. Please note
that Fox Thermal reserves the right to change and/or improve the
product design and specication without notice.
Fox FT3 Manuals:
• Model FT3 Instruction Manual
• Fox FT3 View™Instruction Manual
• Fox FT3 HART Manual
• Fox FT3 Data Logger Manual
FT3 Modbus
Notice
FOX THERMAL
2

FT3 Modbus
Table Of Contents
TABLE OF CONTENTS
1. Modbus Introduction Page 4
2. Modbus Protocol Page 4
3. RS485 Wiring for Modbus Page 5
4. FT3 Commands Supported by Modbus Page 6
5. Modbus Programming Page 12
10. Glossary of Terms and Abbreviations Page 16
11. Index Page 17
3

Scope
Thank you for purchasing the model FT3 thermal gas mass ow meter from Fox Thermal.
The model FT3 is one of the most technically advanced ow meters in the world. Extensive
engineering effort has been invested to deliver advanced features, accuracy measurement
performance and outstanding reliability.
This document describes the Modbus implementation using RS485 serial communication
physical layer for the Fox Thermal FT3 mass ow meter based on the Modicon Modbus
Protocol (PI-MBUS-300 Rev. J).
Modbus Protocol
MODBUS Protocol is an application layer messaging protocol that provides client/sever
communications between devices. MODBUS is a request/reply protocol and offers services
specied by function codes.
The size of the MODBUS Protocol Data Unit is limited by the size constraint inherited from the
rst MODBUS implementation on Serial Line network (max. RS485 Application Data Unit = 256
bytes).
Therefore, MODBUS PDU for serial line communication = 256 – Server address (1 byte) – CRC
(2 bytes) = 253 bytes.
RS485 ADU = 253 + Server address (1 byte) + CRC (2 bytes) = 256 bytes.
For more information on MODBUS go to the web site http://www.modbus.org/.
Command Request:
<Meter Address> <Function code> <Register start address high> <Register start address
low> <Register count high> <Register count low> <CRC high> <CRC low>
Command Response:
<Meter Address> <Function code> <Data byte count> <Data register high> <Data
register low> ... <Data register high> <Data register low> <CRC high> <CRC low>
iNote: The data in shown in brackets < > represents one byte of data.
Model FT2A
Model FT2A
FT3 Modbus
4
Modbus Introduction
MODBUS PROTOCOL

Tx/Rx (+)
Tx/Rx (-)
Communication Common
Cable Shield
Termination Resistor Jumper JP1
Termination Resistor Jumper JP1 (detail)
FT3 Modbus
5
MODBUS WIRING
RS485 Wiring for Modbus
Wiring connections are made to terminal block TS5 for RS485 communication.
The Tx/Rx+ signal connects to pin 1, Tx/Rx- connects to pin 2 and communication common to
pin 3, and the cable shield to pin 4 as shown in Figure 3.1.
Termination Resistor
Connect a termination resistor across the receive/transmit signals of the last device on the
RS485 communication line. To connect the 121 ohm termination resistor on the FT3, set JP1 to
the TERM position.
Disconnect the termination resistor on all other external RS485 devices. The termination
resistor of the FT3 is disconnected by setting JP1 to the NC (Not Connected) position.
Fig. 3.1: RS485 Wiring
iNote: JP1 jumper will either be in the NC or TERM position. It should be in the TERM
position on the last meter in the Modbus daisy chain.
RS485 Wiring: Modbus

FT3 Commands Supported
The FT3 supports the following commands:
1) Command 03: Read holding registers
2) Command 04: Read input register.
3) Command 06: Preset single register
Read Holding Registers (command 03)
This command reads the basic variable from the FT3 and has the following format:
Request:
<Meter Address> <Command code=03> <Register start address high> <Register start
address low> <Register count high> <Register count low> <CRC high> <CRC low>
Response:
<Meter Address> <Command code=03> <Byte count> <Data high><Data low> ... <Data
high><Data low> <CRC high> <CRC low>
Example:
Request data register at starting address 0x0000 and specifying only 1 register
<0x01> <0x03> <0x00> <0x00> <0x00> <0x01> <0x0a> <0x84>
Response:
<0x01> <0x03> <0x02> <xx> <xx> <CRC high> <CRC low>
Where xx xx is the data register value.
Table 4.1: FT3 Modbus Holding Registers
Register
Address
Modbus
Address
Data Type Scaling Comment
0x00 40001 Flow in Eng units (low) No Mass ow in selected units
0x01 40002 Flow in Eng units (high) No
0x02 40003 Total (low) No Total in selected units
0x03 40004 Total (High) No
0x04 40005 Temperature (low) *10 Temperature in selected units
* 10
0x05 40006 Temperature (high) *10
0x06 40007 Elapsed time (low) *10 Elapsed time in hours * 10
0x07 40008 Elapsed time (high) *10
0x08 40009 Velocity (Low) No Velocity in nm/hr
FT3 Modbus
6
FT3 Commands Supported by Modbus
MODBUS - FT3 COMMANDS

Register
Address
Modbus
Address
Data Type Scaling Comment
0x09 40010 Velocity (high) No
0x0A 40011 Flow in Eng units * 10 10 Mass ow in selected units * 10
0x0B 40012 Flow in Eng units *100 100 Mass ow in selected units *
100
0x0C 40013 Total *100 100 Total in selected units * 100
0x0D 40014 Total2 (low, 2 gas curves only) No Total #2 for 2 gas curves
0x0E 40015 Total2 (high, 2 gas curves only) No Total #2 for 2 gas curves
0x0F 40016 Status No Status
0x10 40017 Status2 No Status 2
0x11 40018 Spare/ Not used
0x12 40019 Spare/ Not used
0x13 40020 Flow in Eng units (oat, upper 16 bits) No Mass ow in selected units
0x14 40021 Flow in Eng units (oat, lower 16 bits) No Mass ow in selected units
0x15 40022 Total in Eng units (oat, upper 16 bits) No Total in selected units
0x16 40023 Total in Eng units (oat, lower 16 bits) No Total in selected units
0x17 40024 Total#2 for 2 gas curve (oat, upper 16 bits) No Total in selected units
0x18 40025 Total#2 for 2 gas curve (oat, lower 16 bits) No Total in selected units
0x19 40026 Temperature in selected units (oat, upper 16 bits) No Temperature in selected units
0x1A 40027 Temperature in selected units (oat, lower 16 bits) No Temperature in selected units
0x1B 40028 Elapsed time in hours (oat, upper 16 bits) No Elapsed time in hours
0x1C 40029 Elapsed time in hours (oat, lower 16 bits) No Elapsed time in hours
0x1D 40030 Velocity in selected units (oat, upper 16 bits) No Velocity in selected units
0x1E 40031 Velocity in selected units (oat, lower 16 bits) No Velocity in selected units
0x1F 40032 CAL-V Diff (oat, upper 16 bits) No CAL-V Diff
0x20 40033 CAL-V Diff (oat, lower 16 bits) No CAL-V Diff
0x21 40034 CAL-V Set (oat, upper 16 bits) No CAL-V Set
0x22 40035 CAL-V Set (oat, lower 16 bits) No CAL-V Set
0x23 40036 Spare/ Not used
0x24 40037 Total 24 hrs, Last total record, low register No Tot24hrs: Last total record
0x25 40038 Total 24 hrs, Last total record, high register No Tot24hrs: Last total record
0x26 40039 Total 24 hrs, Current Day (0-6) No Tot24hrs: Current Day
0x27 40040 Total 24 hrs, Current Hour (0-23) No Tot24hrs: Current Hour
0x28 40041 Total 24 hrs, Record day 1, low register No Tot24hrs: Record day 1
0x29 40042 Total 24 hrs, Record day 1, high register No Tot24hrs: Record day 1
0x2A 40043 Total 24 hrs, Record day 2, low register No Tot24hrs: Record day 2
0x2B 40044 Total 24 hrs, Record day 2, high register No Tot24hrs: Record day 2
0x2C 40045 Total 24 hrs, Record day 3, low register No Tot24hrs: Record day 3
0x2D 40046 Total 24 hrs, Record day 3, high register No Tot24hrs: Record day 3
0x2E 40047 Total 24 hrs, Record day 4, low register No Tot24hrs: Record day 4
0x2F 40048 Total 24 hrs, Record day 4, high register No Tot24hrs: Record day 4
FT3 Modbus
7
MODBUS - FT3 COMMANDS
FT3 Commands Supported by Modbus

Register
Address
Modbus
Address
Data Type Scaling Comment
0x30 40049 Total 24 hrs, Record day 5, low register No Tot24hrs: Record day 5
0x31 40050 Total 24 hrs, Record day 5, high register No Tot24hrs: Record day 5
0x32 40051 Total 24 hrs, Record day 6, low register No Tot24hrs: Record day 6
0x33 40052 Total 24 hrs, Record day 6, high register No Tot24hrs: Record day 6
0x34 40053 Total 24 hrs, Record day 7, low register No Tot24hrs: Record day 7
0x35 40054 Total 24 hrs, Record day 7, high register No Tot24hrs: Record day 7
0x36 40055 Total 24 hrs, Last Total, low register No Tot24hrs: Last Total
0x37 40056 Total 24 hrs, Last Total, high register No Tot24hrs: Last Total
0x38 40057 Zero Check Mean (oat, oat upper 16 bits) No Zero Check Mean value
0x39 40058 Zero Check Mean (oat, oat lower 16 bits) No Zero Check Mean value
0x3A 40059 Zero Check Stdev (oat, oat upper 16 bits) No Zero Check Standard deviation
0x3B 40060 Zero Check Stdev (oat, oat lower 16 bits) No Zero Check Standard deviation
0x3C 40061 Zero Check Pipe Ref (oat, oat upper 16 bits) No Zero Check Pipe Reference
0x3D 40062 Zero Check Pipe Ref (oat, oat lower 16 bits) No Zero Check Pipe Reference
0x3E 40063 Zero Check Pipe Diff (oat, oat upper 16 bits) No Zero Check Pipe Difference %
0x3F 40064 Zero Check Pipe Diff (oat, oat lower 16 bits) No Zero Check Pipe Difference %
0x40 40065 Zero Check Bottle Ref (oat, oat upper 16 bits) No Zero Check Bottle Reference
0x41 40066 Zero Check Bottle Ref (oat, oat lower 16 bits) No Zero Check Bottle Reference
0x42 40067 Zero Check Bottle Diff (oat, oat upper 16 bits) No Zero Check Bottle Difference %
0x43 40068 Zero Check Bottle Diff (oat, oat lower 16 bits) No Zero Check Bottle Difference %
0x44 40069 Zero Check Test Time (integer, lower 16 bits) No Zero Check Test Time (sec)
* The data in registers with scaling must be multiplied by 10 or 100 as indicated to be scaled properly.
iNote: Registers A, B & C are provided to get more resolution for low ow and total.
When value exceeds the 16 bit registers, they will be frozen with all 16 bits set. It is also
possible to use the velocity to calculate the ow in engineering units by using the pipe
area and conversion factor for the selected units.
Example:
Request data register at starting address 0x0000 and specifying only 1 register:
<0x01> <0x03> <0x00> <0x00> <0x00> <0x01> <0x0a> <0x84>
Command Response
<0x01> <0x03> <0x02> <xx> <xx> <CRC high> <CRC low>
Where xx is the data register value.
FT3 Modbus
8
FT3 Commands Supported by Modbus
MODBUS - FT3 COMMANDS

Read Input Register (FT3 Status and Status 2, Command 04)
This command is used to report the FT3 status information.
Request:
<Meter Address> <Command code=04> <Register address =0> <Register address =0>
<Register count =0> <Register count =1> <CRC high> <CRC low>
Response:
<Meter Address> <Command code=04> <Byte count =2> <Status High><Status Low>
<CRC high> <CRC low>
The FT3 supports only reading of the FT3 status. The register address must be set to zero
(Modbus Address 30001) and the register count must be set to 1.
Table 4.2: Status Bits Denitions for Command 04, Modbus Address 30001
FT3 Modbus
9
MODBUS - FT3 COMMANDS
FT3 Commands Supported by Modbus
Bit Denition Comment
0Power up indication Cleared when out of the power up sequence
1Flow rate reached high limit threshold Set limit to zero to disable
2Flow rate reached low limit threshold Set limit to zero to disable
3 Temperature reached high limit threshold Set limit to zero to disable
4Temperature reached low limit threshold Set limit to zero to disable
5 Sensor reading is out of range Check sensor wiring
6Velocity ow rate outside of calibration table Check sensor wiring
7 Incorrect Settings Check settings
8 In simulation mode Set simulation value to 0 to disable
9Frequency output is out of range Check frequency output settings
10 Analog 4-20 mA for ow is out of range Check analog output settings
11 Analog 4-20 mA for temperature is out of range Check analog output settings
12 Anybus error Replace display board
13 Bridge Shut Down Check sensor wiring
14 CRC error Check parameters and reset CRC
15 Error in Total Reset total to clear alarm

FT3 Modbus
10
MODBUS - FT3 COMMANDS
FT3 Commands Supported by Modbus
Table 4.3: Status 2 Bits Denitions for Command 04, Modbus Address 30002
Bit Denition Comment
0CAL-V in progress CAL-V in progress
1 ADC12<> ADC24 too far apart Internal ADC calibration out of range
2CAL-V Diff out of range CAL-V Diff out of range
3 Curve #2 Selected (for 2 gas curves only) Curve #2 Selected (for 2 gas curves only)
4 Zero Check Failed Zero Check Failed
5CAL-V/Zero Check Aborted CAL-V/Zero Check Aborted
Preset Single Register (Command 06)
This command is used to perform miscellaneous functions such as clearing the totalizer and
initiating diagnostic operations. The register address is 0x0a (10 decimal, Modbus=40011) and
the data to write is described below.
Request:
<Meter Address> <Command code=06> <Register address high=0x00> <Register address
low=0x0a> <Register data high=0x00> <Register data low =0x02> <CRC high> <CRC
low>
Response:
<Meter Address> <Command code=06> <Register address =0x00> <Register address
=0x0a> <Register data=0x00> <Register data =0x02> <CRC high> <CRC low>
Reset Total:
Address = 40011, data = 0x02
This command is used to clear the Totalizer and elapsed time registers
Reset 24 hours Total:
Address=40011, data = 180 (0xB4)
This command reset the 24 hours 7 days record including the day and hours counters
Reset 24 hour time:
Address=40011, data = 181 (0xB5)
This command reset the 24 hours day and hours counters.

FT3 Modbus
11
MODBUS - FT3 COMMANDS
FT3 Commands Supported by Modbus
24 hours Event:
Address=40011, data = 182 (0xB6)
This command generates a 24 hours event, the same way as when the 24 hours counter
rolls over. This may be useful to record total over a shorter period.
CAL-V Verify:
Address=40011, data = 161 (0xA1)
This command initiates a "CAL_V Verify". This operation may take 4 minutes to complete
and will stop the meter from calculation ow. The Status2 bit D0 may be monitored to check
for completion.
Zero Check In-Pipe Verify:
Address=40011, data = 173 (0xAD)
This command initiates a "Zero Check In-Pipe Verify". This operation does not affect ow
calculations. The register 40069 may be monitored to check for completion.
Zero Check In-Bottle Verify:
Address=40011, data = 176 (0xB0)
This command initiates a "Zero Check In-Bottle Verify". This operation does not affect ow
calculations. The register 40069 may be monitored to check for completion.
Switch to Curve #1:
Address=40011, data = 170 (0xAA)
This command initiates a command to switch to gas curve 1 when congured for 2 gas
curves. Make sure that the input contact is not programmed for curve switching
Switch to Curve #2:
Address=40018, data = 171 (0xAB)
This command initiates a command to switch to gas curve 2 when congured for 2 gas
curves. Make sure that the input contact is not programmed for curve switching.

Enter the Programming Mode
Press the F1 or the F2 key repeatedly, in the normal running mode, until the following screen is
shown. This enters the programming mode:
F1 F2 F3 F4
Press YES (F4) and then the following screen will prompt the user to enter the password if
enabled:
F1 F2 F3 F4
Enter the correct password. Default password for Level 1 is 1234.
Press the UP (F1) or DN (F2) key to select a new digit or character, the cursor points to the
selected digit. Press NXT (F3) to select the next digit and OK (F4) to accept the entry.
If the UP (F1) or DN (F2) keys are held down for more than 1 second, new digits will be selected
at an increasing rate.
If the wrong password is entered, the message “Wrong Password” will be displayed for a few
seconds and then return to the programming entry screen. If the password is accepted, the
following screen will be shown:
F1 F2 F3 F4
This is the base screen for the programming mode. To exit the programming mode, press EXIT
(F4) repeatedly until “Normal Mode” screen is displayed.
SET PARAMETERS?
NO YES
PASWD:_
UP DN NXT OK
SET PARAMETERS?
I/O FLO DSP EXIT
FT3 Modbus
OPERATION
12
MODBUS PROGRAMMING
Modbus Programming

SET PARAMETERS
I/O FLO DSP EXIT
SET I/O
COM I/O 420 EXIT
Comm=Modbus
NXT OK
None
Modbus
HART
Baud=9600
NXT OK
Parity=EVEN
NXT OK
Address=02
CHG OK
Modbus
only
1200
2400
4800
9600
NONE
ODD
EVEN
01-247
Enter menu by scolling to display 4
and entering the password
19200
FT3 Modbus
OPERATION
13
MODBUS PROGRAMMING
Fig. 5.1: Menu Tree: Comm Selection and Programming
Modbus Programming

Communication Protocol and Parameters
To program the communication parameters, press I/O (F1) key from the base menu.
F1 F2 F3 F4
Then press I/O (F1) again:
F1 F2 F3 F4
Then press COM (F1) to select communication parameters.
Set Bus protocol for Modbus:
F1 F2 F3 F4
Press NXT (F1) repeatedly until Modbus is selected as shown and then press OK (F4) to accept
the setting.
Selections are: "Modbus"
"HART"
"None"
Set Baud Rate communication parameter:
F1 F2 F3 F4
SET I/O
I/O FEQ 420 EXIT
SET I/O
COM CTC EXIT
Bus=Modbus
NXT OK
Baud=9600
NXT OK
FT3 Modbus
14
MODBUS PROGRAMMING
Modbus Programming

Press NXT (F1) repeatedly until the correct Baud Rate is shown and then press OK (F4) to accept
the setting.
Selections are: “19200”
“9600”
“4800”
“2400”
“1200”
F1 F2 F3 F4
Press NXT (F1) repeatedly until the correct selection is shown and then press OK (F4) to accept
the setting.
Selections are: “NONE”
“ODD”
“EVEN”
Set Unit Address:
F1 F2 F3 F4
Press CHG (F1) to change the Modbus communication Address.
Press the UP (F1) or DN (F2) keys to select the value for the Modbus Address. The cursor points
to the selected digit. Press NXT (F3) to select the next digit and OK (F4) to accept the setting.
It is very important that there are not two devices with the same Modbus address. To avoid
conicts, each Modbus slave must have a unique address. Range is from 01 and 247.
Note: Power to the FT3 must be cycled off and on for the new Modbus settings to take effect.
Parity=EVEN
NXT OK
Address=02
CHG OK
FT3 Modbus
15
MODBUS PROGRAMMING
Modbus Programming

Aa
FT3 Modbus
16
DEFINITIONS
Denitions
Glossary of Terms
and Denitions
ADD Address
ADU Application Data Unit
COM Communication
CRC Cyclic Redundancy Check
NC Not Connected
PC Personal Computer
PDU Protocol Data Units
NRT Non Resetting Totalizer
TERM Terminal

FT3 Modbus
17
Index
INDEX
Index
Modbus
FT3 Commands Supported, p. 6
Preset Single Register, p. 10
Programming, p. 12
Protocol, p. 4
Read Holding Registers, p. 6
Read Input Registers, p. 9
Status Bits, p. 9
Wiring, p. 5
Programming
Menu Tree, p. 13
Modbus, p. 15
RS485 Wiring
Modbus, p. 5
Termination Resistor, p. 5
Wiring,
Modbus, p. 5

i
Caution
Wiring
Denition of Terms
Information
Aa