Bender ISOMETER isoCHA425 Manual page 21

Data access using the Modbus RTU protocol
7.3 Exception code
If a request cannot be answered for whatever reason, the ISOMETER® will send a so-called
exception code with which possible faults can be narrowed down.
Exception code
0x01 Impermissible function
0x02 Impermissible data access
0x03 Impermissible data value
0x04 Internal fault
0x05 Acknowledgement of receipt (answer will be time delayed)
0x06 Request not accepted (repeat request, if necessary)
7.3.1 Structure of the exception code
Byte Name
Byte 0 ISOMETER® Modbus address
Byte 1 Function code (0x03) + 0x80
Byte 2 Data (exception code)
Byte 3, 4 CRC16 Checksum
21
Description
Example
0x03
0x83
0x04
0xE133
Data access using the Modbus RTU protocol
isoCHA425_D00352_01_M_XXEN/10.2019