Ch a pt er 9 T ro u bl es h oo t in g9 - 39_9.1 Inspection and Troubleshooting9.1.1 Basic InspectionThis chapter describes errors which occur when the system operates, the causes and the corrective actions for the theerrors. Before troubleshooting an error, you have to determine the reason and the cause for the error. There are basicinspections which are required to be conducted before you start to determine the reason and cause as below.(1) The following items have to be checked. The PLC system must operate under the proper operating conditions specified in the manuals, e.g. theenvironment specifications, the electrical specifications, the mechanical vibration level, and more. The power is supplied to the equioment or the location where the PLC is installed, and the power supplied to thePLC system is normal. The backplanes, modules, terminals, and cables are installed properly. Every LED indicator is in the normal state. The setting of the switches is correct.(2) Follow the instructions below to check the operating state of the AH system. Turn On/Off the RUN/STOP switch. Check the condition for the running/stopping of the CPU. Check and eliminate the influences which could be caused by external devices. Monitor the operating state of the system and the error logs by means of ISPSoft.(3) After inspection item (1) and (2) is conducted, you may determine the scope of the reasons that cause the errors asfollows: Determine the errors to be caused by AH system, or by external devices. If the error is caused by AH system, you may determine if the error is a CPU error or a module error. Error codesand indicators might need to be checked. Refer to the following sections for details. When the hardware that has errors is identified, you can further confirm if the error are caused by parametersettings or the by the control program.9.1.2 Clearing the Error StateIf an error occurs in a system, you can try to clear the error state in the following ways. However, if the cause to the errorstill exists after the error state is cleared, the error will occur in the system again.(1) Turn the RUN/STOP switch on the CPU to STOP, and then turn to RUN.(2) Power Off the CPU, and then power On again.(3) Clear the error log by means of ISPSoft.(4) Reset the CPU or restore the PLC to the factory setting. Download the program again, and execute the program.
