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SensyMaster FMT230, FMT250
THERMAL MASS FLOWMETER | OI/FMT230/250-EN REV. C
… 8 Commissioning and operation
… Interface description
0x08 Diagnostics
Only the subfunction ‘Return Query Data (0x00, 0x00)’ is supported.
If the device receives a query telegram, the telegram is sent back to the Master without changes.
The query and reply telegrams are designed as follows:
Byte Description
1
Slave device code
2
Diagnostics Function Code, 0x08.
3, 4
Sub-query identifier, 0x00, 0x00.
5 to (5+n)-1
Diagnostics query data. (Of length ‘n’).
(5+n)
(5+n)+1
Check sum (CRC) of the Modbus telegram
0x10
Write Multiple Registers
The ‘Write Multiple Register’ function code is used to write a value in the ‘Holding Register’ of the device.
The query telegram is designed as follows:
Byte Description
1
Slave device code
2
Write Multiple Registers Function Code, 0x10.
3, 4
Holding register address. 16-bit value indicating the address of the first holding register to write.
5, 6
Holding register count. 16-bit value indicating the number of holding registers to write
7
Byte count ('n'), number of data bytes in the request.
8 to (8+n)-1
Holding register message data. The data to write to the holding registers.
(8+n)
(8+n)+1
Check sum (CRC) of the Modbus telegram
The reply telegram to a successfully processed query is designed as follows:
Byte Description
1
Slave device code
2
Write Multiple Registers Function Code, 0x10.
3, 4
Holding register address. 16-bit value indicating the address of the first holding register.
5, 6
Holding register count. 16-bit value indicating the number of holding registers written.
7, 8
Check sum (CRC) of the Modbus telegram