Omron E5 D Series Communications Manual page 78

4 Modbus Communications Procedure
4-1-2 Response Frame
Normal Response Frame
Slave Function
address code
1 1
Error Response Frame
Function
Slave
code
address
1 1
CRC-16 calculation range
Slave address
Function code
Error code
CRC-16
4 - 4
Data
CRC-16 calculation range
Error
CRC-16
code
1
2 bytes
The number specified in the command frame is entered as-is. This is the unit
number of the Unit returning the response.
This is the received function code with the hexadecimal value of H'80 added
to indicate that the response is an error response.
Example: Received function code = H'03
Function code in response frame when an error occurred = H'83
This code indicates the kind of error that occurred.
Cyclic Redundancy Check
This check code is calculated with the data from the slave address to the end
of the data.
The check code is 2-byte hexadecimal.
CRC-16
2 bytes
E5@D Digital Temperature Controllers Communications Manual (H225)