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

6.8

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.
MELSEC iQ-F FX5U User's Manual (Hardware)
MELSEC iQ-F FX5UC User's Manual (Hardware)
• Wiring
Verify that all communication equipment is correctly wired. (Page 154 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 236 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 159 Communication Settings)
After changing any communication setting, make sure to turn the PLC power from OFF→ON, or reset.

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 CH3
SM8500 SM8510 SM8520
SD
On
Off
On
Off
FX3 Series
compatible
CH4 CH1 CH2
SM8530 SM8063 SM8438
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 Description
Serial communication error Turns ON when an error occurs in serial
communication.
6 NON-PROTOCOL COMMUNICATION
177
6.8 Troubleshooting
6