Mitsubishi Electric RD77MS4 - Page 577

14 TROUBLESHOOTING
14.1 Troubleshooting Procedure
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*1 When all axes are stopped or on standby, the AX LED turns OFF.
*2 When any of the axes is in operation, the AX LED turns ON.
*3 When an error occurs in any of the axes, the AX LED is flashing.
When the RUN LED turns off
If there is no problem on the above check items, a hardware failure may have occurred. Reset the CPU module and check
that the RUN LED turns on.
If not, the possible cause is a hardware failure. Please consult your local Mitsubishi representative, explaining a detailed
description of the problem.
When the ERR LED flashes
When the ERR LED turns on and AX LED flashes
When the ERR LED turns on
Other than those above
Reset the CPU module and check that the module is in the normal status.
If the status is not changed, the possible cause is a hardware failure. Please consult your local Mitsubishi representative,
explaining a detailed description of the problem.
Online module
change
RUN ●
ERR 
AX1 
AX2 
AX3 
AX4 
Module remove selection in
operation

AX1-8 
AX1-16 
RUN 
ERR 
AX1 
AX2 
AX3 
AX4 
Module change in
operation

AX1-8 
AX1-16 
Check item Action
Is the power supplied for the power supply module? Check that the voltage supplied to the power supply module is within the rated range.
Is the LED of the power supply module turned on? If the LED is not turned on, refer to the following.
MELSEC iQ-R CPU Module User's Manual (Application)
Is the power supply capacity sufficient? Calculate the total current consumption of the modules connected with the base unit (CPU
module, I/O modules, and intelligent function modules) and check that the power supply
capacity is not insufficient.
Is the module connected with the base unit correctly? Check the state of connection with the module.
Check item Action
Is there a moderate error? • An error may have occurred in the CPU module. Check the error occurred in the CPU
module and take a corrective action.
• A hardware failure may have occurred. Reset the CPU module and check that the RUN LED
turns on. If not, the possible cause is a hardware failure. Please consult your local Mitsubishi
representative, explaining a detailed description of the problem.
Check item Action
Is there a minor error? Check the error code and take a corrective action.
Check item Action
Is there a synchronous encoder axis error? Check the error code and take a corrective action.
RD77MS status LED display Description Remedy