4Common problem

Various IC automatic burning machines and testing machines, supporting chips in various packages (tape, tube mounting, tray), and automatic burning and testing of ICs in DIP, SDIP, SOP, SSOP, TSSOP, MSOP, etc. There is a solution.

The indicator lights and internal equipment of SR PLC are helpful for troubleshooting the entire PLC control system. The programmer is the main diagnostic tool, which can be easily plugged into the PLC. The status of the entire control system can be observed on the programmer. When you look for the fault of the control system with PLC as the core, as a habit, you should bring a programmer.

Basic troubleshooting sequence.

Ask the following questions and negate one by one according to the reasonable actions found. Replace various modules in the SR step by step until all the faults are eliminated. All major corrective actions can be completed by replacing the module. Except for a screwdriver and a multimeter, no special tools, oscilloscopes, advanced precision voltmeters or special test procedures are needed.

1. Is the PWR (power supply) light on? If it does not light up, check the power supply voltage at the voltage input terminal (98-162VAC or 195-252VAC) of the frame that uses AC power; for the frame that requires DC voltage, measure the DC voltage between +24VDC and 0VDC, if it is not suitable AC or DC power supply, the problem occurs outside the SR PLC. If the AC or DC power supply voltage is normal but the PWR light is off, check the fuse and replace the CPU frame if necessary.

2. Is the BATT (battery) light on? If it is on, the lithium battery needs to be replaced. Since the BATT light is only an alarm signal, even if the battery voltage is too low, the program may not be changed yet. After replacing the battery, check the program or let the PLC test run. If the program has been wrong, after completing the system programming initialization, reload the program recorded on the tape into the PLC.

3. Is the RUN light on? If it does not light, check if the programmer is in the PRG or LOAD position, or if there is a program error. If the RUN light is off and the programmer is not plugged in, or the programmer is in RUN mode and no error code is displayed, you need to replace the CPU module.

4. Is the PWR (power supply) light on? If it is on, check the error code, compare the code definition in the error code table, and make corresponding corrections.

5. In a multi-frame system, if the CPU is working, the RUN` relay can be used to check the work of several other power supplies. If the RUN relay is not closed (high-impedance state), follow the first step above to check the AC or DC power supply. If the AC or DC power supply is normal and the relay is disconnected, you need to replace the frame.

General troubleshooting steps (other steps are related to the user’s logical knowledge. The following steps are actually relatively common. For the specific application problems you encounter, you still need to modify or adjust. The best tool for troubleshooting is yours Feeling and experience. First, plug in the programmer and turn the switch to the RUN position, then follow the steps below.

1. If the PLC stops at a place where some output is excited, generally in an intermediate state, look for the signal that caused the next operation (input, timer, line, drum controller, etc.). The programmer will display the ON/OFF status of that signal.

2. If the signal is a line, there is no output or the output is different from the line, you have to use the programmer to check the output drive logic and check the program list. The inspection should be carried out from there to the left, and find the first non-connected contact. If the one that is not connected is an input, check the input point according to the second and third steps. If it is a line, press the fourth Step and fifth check. Make sure that the main control relay step affects the logic operation.

3. If the input status of the burner is consistent with the LED indication of the input module, compare the status of the light-emitting diode and the input device (button, limit switch, etc.). If the two are different, measure the input module. If there is a problem, you need to replace the I/O device, field wiring or power supply; otherwise, replace the input module.

4. If the writer inputs a signal, compare the status displayed by the programmer with the LED indication of the input module. If the result is inconsistent, replace the input module. It is found that there are multiple modules on the expansion frame to be replaced, so before you replace the modules, you should check the I/O expansion cable and its connection.

5. If the signal controls a counter, first check the logic that controls the reset, and then the counter signal. Follow steps 2 to 5 above.