10. Troubleshooting
10.1.4Input check
If the program is running but the external input signal is not read normally, check the following points:
Is the input status LED
changed ON/OFF according to the corresponding input device operation ?
Yes
Connect the programming
tool, and monitor the
corresponding X device state
in RUN mode
Not normal
Check whether the X device
is forced or not
Not forced
Check whether the I/O allocation table is identical to the actual I/O configuration
Not identical
Execute the automatic I/O
allocation, and check whether the I/O allocation table is now identical to the actual I/O configuration
Still not identical
Is the allocation mismatch for
a specific option card, I/O module, or expansion unit ?
No
Is the allocation mismatch for all I/O modules mounted on the expansion rack ?
If not, check the input voltage at the T1/T1S’s input terminals.
If the voltage is not normal, check the input device and the cable.
If the voltage is normal, the T1/T1S’s input circuit may be faulty.
If the monitored X device state is identical to the state of the input status LED, the cause may lie in the user program or in the environment.
If it is forced, release the force designation then execute the EEPROM write operation.
If identical, the T1/T1S’s internal circuit or the input circuit may be faulty.
If it becomes identical, execute the EEPROM write operation.
If so, the card, module or expansion unit may be faulty. For expansion unit, check the expansion cable also.
If so, check the connection between the T1/T1S basic unit and the expansion rack. If not, the T1/T1S basic unit may be faulty.
Basic Hardware and Function 297
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