27 TROUBLESHOOTING
27.3 Troubleshooting by Symptom
463
27
RUN LED turns OFF
ERR LED flashes
• Remarks
The error code when ERR LED flashes is stored in the buffer memory shown below.
Symptom Cause Corrective action MC Non Bi Pd
RUN LED on C24 turns OFF The module is not mounted
properly.
• Mount the C24 on the base unit properly.
Power module 5 VDC
consumption current is
insufficient.
• Calculate the 5 VDC consumption current of each mounted
module. If the current capacity is insufficient, review power
module selection.
Extraneous noise causes
abnormal operation of C24.
• Review the wiring so that the shield is single-point
grounded.
• When ground is used with other devices, ground the C24
independently.
Symptom Cause Corrective action MC Non Bi Pd
ERR LED flashes. The communication protocol
setting or transmission setting
is incorrect.
• Read the error code from the buffer memory, and check the
error contents and change to the correct setting.
The parameter settings are
incorrect.
• Review the parameter settings with Engineering tool. Then,
write the parameter settings to the CPU module, and reset it.
• Review each settings for the parameters set in the buffer
memory, and turn ON the 'CH mode switching request'
(Y2/Y9). For more details on 'CH mode switching request',
refer to the following section.
(Page 380 I/O Signals for Handshake with CPU Module
and Buffer Memory)
The protocol setting data
stored in the CPU module is
not for MELSEC iQ-R series
C24.
• Write the protocol setting data for MELSEC iQ-R series C24
to the CPU module.
Error factor Error code storage buffer memory
Address Name
CH1 CH2
Parameter setting error Un\G515 Parameter setting error, mode
switching error status
Parameter error
(Module parameter)
Un\G20224 to 20231 Error address storage area
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