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*1 When the MELSECNET/H remote I/O module is used in a redundant power supply system, the cause of failure in the
power supply module can be diagnosed with the status of the REM. LED and ERR. LED.
The faulty power supply module can be identified in the corresponding error code. ( Page 93, Section 7.4.3)
Check the failure status of the power supply module with the LEDs of the module. When the power supply module is
mounted on an extension base unit, the failure status can also be checked with the ERR. contact of the module.
( QCPU User's Manual (Hardware Design, Maintenance and Inspection))
ERR.
*1
On (red)
• Station number setting error (other than 1 to 64), mode setting error (set to disabled), or
operating condition setting error (in parameter)
• A station with the same station number exists in the network.
• Parameter data received from the remote master station has an error.
• Watchdog timer error (The RUN LED is off.)
Flashing
• An error is detected at the test operation of the MELSECNET/H remote I/O module.
• The setting of the mode setting switch or station number setting switches has been changed
during the operation.
Off Normal operation
L ERR.
On (red)
Watchdog timer error (The RUN LED is off.)
Communication error (One of the following errors has been occurred.)
•CRC
This error occurs due to a fault in the cable or noise.
• OVER
This error occurs when the received data is erased before it is written to the internal memory
because the next data is received. The possible error cause is a hardware failure at the
receiver part of the MELSECNET/H remote I/O module.
• AB.IF
This error occurs when the number of the bits indicating "1" in the received data within a
frame exceeds the limit or the received data length is shorter than that defined in the
specifications.
•TIME
This error occurs when the baton pass is not handed to the host station within the monitoring
time.
•DATA
This error occurs when the data with abnormal code is received.
• UNDER
This error occurs when the internal processing of send data is not performed at a fixed
interval.
•LOOP
This error occurs when the forward loop or reverse loop line is faulty. The power of the
adjacent station in the direction to the host station is off or the hardware failure exists on the
send station.
<Action>
Check the connector for disconnection, looseness, and IN/OUT misconnection; and the cable
for disconnection, crack, and routing.
• For details, refer to the network diagnostics. ( Page 75, Section 7.2)
Off No communication error
Power supply
module
Cause of failure REM. LED ERR. LED
Failure of one module
Input power supply OFF, fuse blown Off On
Internal failure
Off On
On Off
Failure of both modules
Input power supply OFF, fuse blown Off Off
Internal failure
Off Off
Off On
On Off
Name LED status Description