PLC common method of handling fault

Continuous growth stage are designed to work the system. However, occasionally some places need to be modified on the action quickly and modify them to find this place is very important. Changes occurred in the PLC needs a lot of time outside the movement. 


All types of general PLC (The Electronic Industry Co., Ltd. Wuxi Huaguang production of SR series PLC, as description of model, the remaining much the same type PLC) are designed to work uninterrupted growth stage system. However, occasionally some places need to be modified on the action quickly and modify them to find this place is very important. Changes occurred in the PLC needs a lot of time outside the movement. Find the equipment failure 


SRPLC the lights and machines, equipment, benefits of the PLC control system to find the fault. Programmer is the main diagnostic tool, he can easily plug into the PLC above. The programmer can observe the state of the whole control system, when you go to find the PLC as the core of the control system failure, as a habit, you should take a programmer. 


Basic order to find fault Ask the following questions, and found reasonable under the action one by one negative. SR step by step to replace the various modules, until the failure were excluded. All major amendments to replace the modules through to complete the action. In addition to a screwdriver and a multimeter, the do not need special tools, no scope, high precision voltage meter or special test procedures. 


1, PWR ( Power supply ) No lights? If you do not shine, in the framework of AC power supply voltage input (98-162VAC or 195-252VAC) Check power supply voltage; the framework for the DC voltage needed to measure +24 VDC and the DC voltage between 0VDC side, if not suitable AC or DC power supply, the problem occurs outside the SRPLC. Such as AC or DC power supply voltage normal, but the PWR light does not shine, check the fuse, if necessary, replace the CPU on the framework. 


2, PWR (power) light is not? If so, the examination showed that the error code, control code error code table definition be amended accordingly. 


3, RUN (running) lights not? If you do not light, check the programmer is not in the PRG or the LOAD position, or is not a procedural error. Such as RUN lamp is not lit, the programmer did not plug in, or programmer in RUN mode and not display an error code, you need to replace the CPU module. 


4, BATT (battery) light is not? If so, the need to replace the lithium battery. BATT light just as alarm signal, even if the battery voltage is too low, the program may still not change. After replacing the battery, check the PLC program or to test run. If the program has been wrong, after the completion of system initialization program will be recorded on tape procedure reload PLC. 


5, in a multi-frame system, if the CPU is working, can RUN ` Relay To check the work of several other power. If the RUN relay is not closed (high impedance state), according to the first step mentioned above check the AC or DC power supply such as AC or DC power supply is disconnected normally and relays, you need to replace the frame. 


General troubleshooting steps Other Steps in the logic of knowledge about the user. The following steps, in fact a more general, for your specific application problems encountered, yet modification or adjustment. Failure to find the best tool is your sense and experience. First, plug in programmer and switch hit RUN position, and then follow these steps. 


1, if the PLC to stop the output to be motivated in some places, usually in the middle of the state, causing the next step is to find the signals occurred (input, timer, line River, drum controller, etc.). Programmer will display the signal ON / OFF status. 


2, if the input signal, the program displays the status of the LED with the input module for direct comparison, the results are inconsistent, then replace the input module.

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