Mitsubishi Electric MELSEC FX Series User Manual page 155

FX communication
12.4.3 Diagnostics
1 ) Check the status of the RD(RXD) LED and the SD(TXD) LED provided on each
communication unit.
• If both of them are lighted and extinguished, nothing is wrong.
• If the RD(RXD) LED is lighted/extinguished but the SD(TXD) LED is not lighted/
extinguished (not lighted at all), check the setting of the station No. and the transmission
rate (baud rate).
• If the RD(RXD) LED is not lighted/extinguished, check the wiring and confirm the
connection with the programmable controller.
2 ) Make sure that the communication procedure is performed correctly. If it is not performed
correctly, correct the setting in the computer.
3 ) Check the NAK error code and programmable controller error code.
Please see the following section 12.4.1 and section 12.4.2.
Diagnostics 12
12
12-5