Panasonic FP-X0 L14R User Manual page 74

Response message
The PLC that received the command in the example above sends the processing results to the computer.
1. Header (Start code)
A "%" (ASCII code: H25) or a "<" (ASCII code: H3C) must be at the beginning of a message.
The response must start with the same header that was at the beginning of the command.
2. Unit number
The unit number of the PLC that processed the command is stored here.
3. Text
The content of this varies depending on the type of command. If the processing is not completed
successfully, an error code will be stored here, so that the content of the error can be checked.
4. Check code
BCC (block check code) for error detection using horizontal parity. The BCC starts from the header and
checks each character in sequence, using the exclusive OR operation, and replaces the final result with
character text.
5. Terminator (End code)
There is always a " C R " (ASCII code: H0D) at the end of the message.
Note: When reading
If no response is returned, the communication format may not be correct, or the command may not
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have arrived at the PLC, or the PLC may not be functioning.
Check to make sure all of the communication specifications (e.g. baud rate, data length, and parity)
match between the computer and the PLC.
If the response contains an "!" instead of a "$", the command was not processed successfully. The
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response will contain a communication error code. Check the meaning of the error code.
Unit number and command name are always identical in a command and its corresponding response
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(see below). This makes the correspondence between a command and a response clear.
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