Sensor Electronics SEC 3000, Instruction And Operation Manual

Page: 380 / 489

SEC 3120 16-bit Modbus Manual Page 41 Of 46 Sensor Electronics Corporation
For Version 1.2 and above December 2012 P/N 1580282, Rev. 1, 20121228
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:
The normal response is an echo of the query header, returned after the register
contents have been written.
Write Multiple Holding Registers Query
Field Name Example (Hex)
Slave Address
11
Function Code 10
Address High 08
Address Low 46
Item Count High 00
Item Count Low 03
Num Data Bytes 06
Data High (42119) 42
Data Low (42119) 59
Data High (42120) 43
Data Low (42120) C8
Data High (42121) 0F
Data Low (42121) 5C
CRC Low Byte 92
CRC High Byte 27