Sensor Electronics SEC Millenium Series Instruction And Operation Manual page 380

The normal response is an echo of the query header (which contains the
unit number, function code, starting address and number of registers).
Query
The query message specifies the register reference to be preset. Registers are
addressed starting at zero: register 1 is addressed as 0.
Here is an example of a request to write holding registers 42119 - 42121 to set the
low alarm set point floats 400.12 (43C8 0F5C Hex) in slave device 17, for sensor 1:
Write Multiple Holding Registers Query
Field Name
Slave Address
Function Code
Address High
Address Low
Item Count High
Item Count Low
Num Data Bytes
Data High (42119)
Data Low (42119)
Data High (42120)
Data Low (42120)
Data High (42121)
Data Low (42121)
CRC Low Byte
CRC High Byte
The normal response is an echo of the query header, returned after the register
contents have been written.
SEC 3120 16-bit Modbus Manual
For Version 1.2 and above
Example (Hex)
11
10
08
46
00
03
06
42
59
43
C8
0F
5C
92
27
Page 41 Of 46
December 2012
Sensor Electronics Corporation
P/N 1580282, Rev. 1, 20121228