How to troubleshoot Siemens plc peripheral line fault
In the Siemens PLC maintenance work, according to authoritative statistics, the failure rate in the Siemens PLC control system is: CPU and memory accounted for 5%, I/O modules accounted for 15%, sensors and switches accounted for 45%, actuators accounted for 30%, wiring and other aspects accounted for 5%, it can be seen that more than 80% of the failure appears in the peripheral line. The peripheral line is composed of field input signals (such as push-button switches, select switches, proximity switches and switching quantities output by some sensors, relay output contacts or analog quantities converted by analog-to-digital converters, etc.) and field output signals (solenoid valves, relays, contactors, motors, etc.), as well as wires and terminals. When Siemens PLC maintenance, we found that loose wiring, component damage, mechanical failure, interference, etc., can cause peripheral circuit failure. Therefore, Siemens PLC maintenance should be carefully checked, and the replacement components should choose high-quality devices with reliable performance and high safety factor. Some powerful control systems use the fault code table to indicate the fault, which brings great convenience to the analysis and elimination of the fault, and should be made good use of PLC maintenance.
Siemens PLC maintenance example: the control system of the underwater pelletizing machine failed, and Siemens PLC maintenance engineers found that I5.4 no input led to Q7.0 no output, and the pelletizing machine could not be opened. After inspection, it was found that the signal converter and the proximity switch were damaged at the same time, and they were normal after replacement. When Siemens PLC maintenance, such faults have a certain degree of concealment, and the system schematic and logic diagram such as multimeter and Siemens touch screen should be eliminated step by step.
SIMATICS5 control system integrates digital circuit, analog circuit, relay circuit and computer technology, with high stability and reliability, but once MT6100IV2 failure will cause the whole system shutdown loss is larger, Siemens PLC maintenance has certain difficulties and high maintenance costs. The use of maintenance tools in addition to the multimeter sometimes also use oscilloscopes and even computers, which requires Siemens PLC maintenance personnel have high professional skills, and have a certain foreign language and computer skills, only after understanding and familiar with the whole system can judge the common faults quickly, eliminate quickly, and reduce maintenance costs as much as possible. Ensure the normal stability of the system.