Cnc Machining Haoyi Model Factory , http://www.yy3dprint.com
In the PLC maintenance work, the peripheral circuit is the input signal from the field (such as the push button switch, selector switch, proximity switch and some sensor output switch, relay output contact or analog-to-digital converter conversion analog, etc.) and field output signal ( Solenoid valves, relays, contactors, motors, etc.), as well as conductors and terminals. During PLC maintenance, we found that loose wiring, damaged components, mechanical failure, and interference can cause peripheral circuit failures. Therefore, when troubleshooting PLC maintenance, you should be careful, and the replaced components should use high-quality devices with reliable performance and high safety factor. Some powerful control systems use fault code tables to represent faults, which greatly facilitate the analysis and troubleshooting of faults. PLC maintenance should be used properly.
Example of PLC maintenance: The control system of the underwater pelletizer failed. PLC maintenance engineers found that no input from I5.4 resulted in no output of Q7.0, and the pelletizer could not be turned on. After the inspection, it was found that the signal converter and the proximity switch were damaged at the same time and were normal after replacement. PLC maintenance, such as this kind of failure has a certain degree of concealment, troubleshooting with multimeter, system schematics and logic diagrams to eliminate.
The SIMATIC S5 control system integrates digital circuits, analog circuits, relay circuits, and computer technology. It has high stability and reliability, but once it fails, it will cause a large loss of the entire system shutdown, PLC maintenance has certain difficulties and maintenance costs Also higher, with the help of maintenance tools in addition to multimeters sometimes use oscilloscopes and even computers, which requires PLC maintenance personnel with high professional skills, and have a certain degree of foreign language and computer skills, only the entire system to understand and familiar with The common faults can be judged quickly and eliminated quickly, and maintenance costs can be reduced as much as possible to ensure the normal stability of the system.
In the PLC maintenance work, according to authoritative statistics, the failure rate in the PLC control system is: CPU and memory 5%, I/O module 15%, sensors and switches 45%, actuators 30%, wiring Such as other aspects accounted for 5%, we can see more than 80% of the faults appear in the peripheral lines.