Despatch Protocol 3 Modbus Communications - Manual (Page 10)

A BOUT T HIS M ANUAL Modbus Programming Manual
10 Version 2
Copyright © 2012 by Despatch Industries.
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Function 06 - Write Single Register
Writes two bytes to a specified word address.
QUERY
Function Address of Word Value to write
06 HI LO HI LO
RESPONSE
Function Address of Word Value written
06 HI LO HI LO
Note:
The Response normally returns the same data as the Query.
Function 08 - Loopback Diagnostic Test
QUERY
Function Diagnostic Code Value
08 HI =00 LO=00 HI LO
RESPONSE
Function Sub-function Value
08 HI=00 LO=00 HI LO
Note:
The Response normally returns the same data as the loopback Query. Other Diagnostic
Codes are not supported.
Function 16 - Write Multiple Registers (0x10 Hex)
Writes consecutive word (two-byte) values starting at the specified address.
QUERY
Function 1 st Write
Address
Number of Words
to Write
Number of
Query Bytes 1 st Query Byte
2 nd Query
Byte
etc Last Query Byte
10 HI LO HI LO →
RESPONSE
Function 1 st Word Address Number of Words
10 HI LO HI LO
Note:
The number of data bytes that can be written in one message is 253 bytes.