Troubleshooting; Checking Communication Status Based On Led Display; Checking Installation; Checking Sequence Program - Mitsubishi Electric FX5 User Manual

5.8

Troubleshooting

This chapter explains troubleshooting and error codes.

Checking communication status based on LED display

Check the status of the LED display of [RD] and [SD] on the CPU module or the communication board/communication
adapter.
LED status
RD
On
On
Off
Off
When normally sending and receiving data with non-protocol communication, the LEDs both flash brightly.
If they do not flash, check the wiring and the communication settings.

Checking installation

• Connection status
The communication cannot be operated if the PLC and the communication board/communication adapter are not
connected correctly.
For the connection procedure, refer to the following.
FX5U User's manual (Hardware)
FX5UC User's manual (Hardware)
• Wiring
Verify that all communication equipment is correctly wired. (Page 131 Wiring)

Checking sequence program

RS2 instruction cannot be used in the same serial port which is being used for any other communication (such as inverter
communication). (Page 212 Combined Use of Serial Communication)

Checking the communication settings

Verify that protocol type is "Non-protocol Communication". When the protocol type is not "Non-protocol Communication",
communication will not function correctly. (Page 136 Communication Settings)
After changing any communication setting, make sure to turn the PLC power from OFFON, or reset the system.

Caution on write during RUN, when RS2 instruction is driven

When the RS2 instruction is eliminated by writing during RUN, non-protocol communication stops immediately.

Checking absence/presence of errors

Serial communication error
■Error flags
If a communication error occurs in the non-protocol communication, the serial communication error flag turns ON.
Verify that the device specified in the table below is ON.
FX5 dedicated
CH1 CH2
SM8500 SM8510
5 NON-PROTOCOL COMMUNICATION
154
5.8 Troubleshooting
SD
On
Off
On
Off
FX3 Series
compatible
CH3 CH4 CH1
SM8520 SM8530 SM8063
Operation status
Data is being sent or received.
Data is being received, but not being transmitted.
Data is being transmitted, but not being received.
Data is neither being transmitted nor being received.
Name
CH2
SM8438 Serial communication error
Description
Turns ON when an error occurs in serial
communication.