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4-31
4 Using Protocol Macros
CJ-series Serial Communications Units Operation Manual for NJ-series CPU Unit(W494)
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Additional Information
Overrun Errors, Framing Errors, Parity Errors and Error Flags
If an overrun error, framing error, or parity error is detected when the protocol macros is used,
the receive data will be stored in the buffer with the error status included. The corresponding
error flags will change to TRUE the following conditions are met.
Data which matches the expected receive message includes error information
When Recv is executed, the expected receive message is searched for in the reception buffer. If
the error information is included in the received data, the corresponding error flags will change to
TRUE.
The following example shows when 100 bytes of data is received that matched an expected
receive message.
Data which does not match the expected receive message includes error information
If error information is included in data that do not match an expected receive message, the data
will simply be discarded and the error flag will remain unchanged. For trace information, all error
details in the reception buffer will be stored within capacity for the trace data.
The following example shows when a parity error occurs for data that does not match an
expected receive message.
Error Flag ON
100 bytes
P: Parity error
(P)
(P)
Error flags remain
unchanged
Data discarded
(P)
(P)
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