6. Troubleshooting
Troubleshooting and Corrective Actions
The ERROR LED
blinks every 0.5
seconds.
Possible causes:
ï‚Ÿ The downloaded PLC program contains invalid instructions or
parameters.
ï‚Ÿ The downloaded PLC program contains illegal program syntax or
devices.
Solutions:
ï‚Ÿ Check the value in D1004 for the error code and the value in D1137
for the Step where an error occurred. And then check the troubleshoot
for the error code in the next section.
The ERROR LED
blinks every 0.2
seconds and waits
for one second and
then starts blinking
0.2 seconds again.
The blinking pattern
keeps going.
The SRAM (static random-access memory) of the PLC or other critical
hardware component is out of order. The PLC CPU cannot read/write data,
cannot execute any communication nor operation. Contact Delta technical
support team or the distributors for further help.
Diagnosing Input
Malfunction
When there are inputs but the input indicator LEDs are OFF,
1. Check the wiring of the input devices.
2. Check that the power is properly supplied to the input terminals.
3. If the power is properly supplied to the input terminal, there is
probably an abnormality in the PLC’s input circuit. Please contact
your dealer.
4. If the power is not properly supplied to the input terminal, there is
probably an abnormality in the input device or input power supply.
Check the input device and input power supply.
When there are no inputs but the input indicator LEDs are ON,
1. Monitor the input condition using a programming tool. If the input
monitored is OFF, there is probably an abnormality in the
PLC’s input circuit. Please contact your dealer.
2. If the input monitored is ON, check the program again. Also, check
the leakage current at the input devices (e.g., two-wire sensor) and
check for the duplicated use of output or the program flow when a
control instruction such as MC or CJ is used.
3. Check the settings of the I/O allocation.
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