SensyMaster FMT230, FMT250
THERMAL MASS FLOWMETER | OI/FMT230/250-EN REV. C
51
Changing an unknown Modbus slave ID
The Modbus Slave ID (address) of the device must be known for
Modbus communication.
Upon delivery, the Modbus Slave ID corresponds to the last two
digits of the serial number of the device (see Figure 47, item
2
).
If the Modbus address is not known, the Modbus Slave ID can be
reset via a Modbus broadcast message. To do this, the following
three Modbus registers must be sent to the bus together with
the function code 16 (0x10) ‘Write Multiple Registers.’
To set the Modbus Slave ID the Sensor ID of the device from the
calibration certificate will be needed.
Figure 48: Sensor ID on the calibration certificate
Address / data type
[register length]
Description
65521 TUSIGN32 [2]
manufacturerDeviceID
The manufacturer code (ABB = 0x1A) and the
device code (FMT = 0x27) must be written to
register 65522.
65523 TUSIGN32 [2]
sensorSerialID
The Sensor ID of the device (on the calibration
certificate). The information must first be written
in the high-byte (65524) of the register.
65525 TUSIGN32 [2]
slaveID
The new Modbus Slave ID must be written in the
high byte (65526) of the register.
The three Modbus registers must now be sent from the Modbus
master to the broadcast address ‘0.’ All of the devices connected
to the bus receive the message, but only the device addressed
via the manufacturer code and the Sensor ID sets the Modbus
Slave ID to the new required value.
1
Functional code 16
2
Broadcast address “0”
3
Register start address
4
Number of registers
5
Manufacturer and device codes
6
Sensor ID
7
New Modbus Slave ID
Figure 49: Write Multiple Registers (example)
