1
YES
NO
YES
NO
YES
Is RD LED
(receive) lit?
Is M8123
turned on?
No receive
completion
All data is
received?
• Check wiring of RS232C cable.
• Make sure wiring of control line is suited to the external device.
• Make sure the external sending device is normal.
• Check the voltage level of RS232C signal.
NO
(Monitoring D8123)
• Check if receive data length is exceeding the data
area length.
When using terminator
• Make sure the external sending device is sending
the terminator.
• Make sure the terminator value matches.
• Match the communication format.
• Check the timing of control line.
• Check if the send data length is not zero when driving RS instruction.
When using header
• Make sure the external sending device is sending the header.
When using terminator
• Check the timing of send, receive.
• Monitor data in hexadecimal notation (HEX).
• Check on/off of M8161.
• Confirm send data format of the sending device.
[ When M8123 is reset, the PC returns to the wait state. ]
Are the
contents of
receive data
unintelligible?
Normal
Receive
completion
NO
YES
