Panasonic FP2 User Manual

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Contents

Panasonic FP2 User Manual Manual pdf 69 page image

Precautions Regarding Serial Data Unit Operation and ProgramsFP2 Serial Data Unit5 − 55.2 Precautions Concerning CommunicationWhen sending dataIf the system is operating with a valid start code, be aware that the data from the mostrecent start code to the end code will be sent as one frame.STX STX ETX STX: Start codeETX: End codeWhen start code is valid: 1 frameWhen start code is not validWhen the start code is valid, data sent without a start code will cause an error and cannotbe sent.When the start code is valid, any other code existing before the start code will cause anerror, and the data cannot be sent.The data being sent should always be written so that it begins with a start code.For sample time out and retry programs, refer to section 8.1.2.5.2.2 End Codes for CommunicationWhen sending data:If there is no end code in the data being sent, a “Sent message length error” will occur,and it will not be possible to send data from the serial data unit.When receiving data:If data is received without an end code, the received data will not be stored into thereceived buffer of the shared memory, so before sending data from the RS232C deviceon the other side, be sure an end code has been specified.5.2.3 Operation If a Communication Error OccursIf a communication error occurs, the ERR LED on the operation status display of theserial data unit lights, but this LED goes out automatically when normal data is received.