Honeywell UDC2500 - Manual (Page 202)

Modbus RTU Function Codes
188 UDC2500 Universal Digital Controller Product Manual 4/07
9.4.1 Write Configuration Examples
Example #1
The following is an example of a request to write the Gain 1 value using Function code
21 (15 Hex).
Request Message (Write Gain 1= 1.5 “ID Tag 1”)
02 15 0B 06 00 03 00 01 00 02 3F C0 00 00 (CRC16)
Where:
02
= Address
15 = Function Code 21 (15 Hex)
0B = Byte Count
06 = Reference Type (IEEE Floating Point)
00 03 = File Number (Access Data Value)
00 01 = Register Address (Standard Access - Gain 1 - ID Tag 1)
00 02 = Register Count (Floating Point Data)
3F C0 00 00 = 1.50
(CRC16)
This is the response to the above request.
Response Message (The response is an echo of the request)
02 15 0B 06 00 01 00 02 00 02 3F C0 00 00 (CRC16)