Xytronix Research & Design WebRelay-10 X-WR-10R12-I User Manual page 73

WebRelay-10 Users Manual
Error Response Frame Example
Field Name
Transaction Identifier
Protocol Identifier
Message Length
Unit Identifier
Function Code
Data
RX String: 00 01 00 00 00 03 FF 85 03
Xytronix Research & Design, Inc.
Length Function
2 bytes Synchronization between messages of
server and client.
2 bytes Zero for Modbus/TCP
2 bytes Number of bytes in frame (below)
1 byte Slave Address (0xff if not used)
1 byte Error code
1 byte Exception code (0x01 - 0x02)
Operation
Example Data
0x0001
0x0000
0x0003
0xFF
0x85
0x02
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