Panasonic FP7 User Manual page 102

Specifications
NOTES

If no response is returned, the communication format may not be correct, or
the command may not 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.

If the response contains an "!" instead of a "$", the command was not
processed successfully. The response will contain a communication error
code. Check the meaning of the error code.

Station no. and command name are always identical in a command and its
corresponding response (see below). This makes the correspondence
between a command and a response clear.
8-8
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