11 Appendix 11.1 Appendix A: Table for Self-detecting Abnormality When you encounter abnormality using the product, you can analyze the problem first by doing the self detections below. DVP-PLC Application Manual 11-1 Abnormality Possible cause Suggested correction Output point abnormality Loosened terminal block Check if the removable terminal block is loosened. The input counting specification may not match the pulse output frequency of the PLC model in use. Check if the hardware is normal by low-frequency pulse counting. Communication abnormality The length of communication cable Make sure the RS-232 cable is at least 3 meters long to ensure normal communication (specification unknown).
Incorrect communication protocol or address setting Broadcast from station 0 first by RS-232 to search for communication protocol and address and later confirm by RS-485 communication. Extension module unable to work Poor connection or MPU problem Make sure the MPU is tightly connected to the extension module and compare to make sure whether the problem lies in the MPU or the extension module. Counter (input point) abnormality The applicable frequency exceeds the maximum bandwidth. The frequency should be within the allowed PLC specifications.
ERROR LED flashes Incorrect program syntax Record the error code first, and write whether the ERROR LED should not flash anymore by syntactically correct program. Model with battery should be checked whether the time of RTC is correct (not being correct means the battery might once be unattached, causing reset of time). L.V. LED On Low input power supply Make sure the power supply voltage is normal. RUN LED Off after execution There is no program inside the new PLC, resulting in misjudgment. Write in the program first.