Omron K7DD User Manual page 126

7 Communications
(6) CRC processing continues to the end of the message, as XOR operations are performed on the
content of the CRC register and the next byte of the message, and step (3) is repeated. The result
is returned to the CRC register.
(7) The result of the CRC calculation (value in the CRC register) is appended to the last byte of the
message.
Slave
address
Response Frame
 Normal Operation:
Slave Function
address code
1 1
 Command Frame Error:
Slave Function
address
code
1 1
CRC-16 calculation range
Slave address
Function code
Data
Error code
CRC-16
7 - 10
If the calculated CRC value is H' 1234
Function
code Data
Data
CRC-16 calculation range
Error
code
CRC-16
1 2 bytes
The number specified in the command frame is entered as-is.
This is a received function code. As for the response frame when an error occurs, H'80 is
added to the received function code to indicate an error response.
Example: If the received function code is H'03, the error response is H'83.
The body text of the response.
This code indicates the kind of error that occurred. Refer to the table below.
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.
H'34 H'12
CRC-16
CRC-16
2 bytes
Power Line Data Generator User's Manual (N233)