WOODWARD 5233-2089 automatic zero adjustment regulator

Description

PLC has strong self-diagnostic ability. When the PLC itself malfunctions or peripheral equipment malfunctions, the LED with diagnostic indication function on the PLC can be used to diagnose.

Below, a PLC is used as a description template, while other types of PLCs are similar and similar. The maintenance, diagnosis, and replacement methods of PLCs are introduced.

Maintenance Overview
Generally, all types of PLCs (using one type of PLC as a description template, while the other types of PLCs are similar) are designed with a long-term uninterrupted working system. However, occasionally there are places where actions need to be modified, and it is important to quickly find the location and modify them. Modifying actions that occur outside of the PLC requires a lot of time.

Finding faulty devices
The indicator lights and internal equipment of the PLC are beneficial for troubleshooting the entire control system of the PLC. The programmer is the main diagnostic tool that can be easily plugged into the PLC. On the programmer, you can observe the status of the entire control system. As a habit, you should bring a programmer or laptop when searching for faults in a PLC based control system.

Basic fault finding sequence
Raise the following questions and deny each one based on the reasonable actions found. Replace various modules step by step until all faults are resolved. All major corrective actions can be completed by replacing the module. Except for a screwdriver and a multimeter, there is no need for special tools, oscilloscopes, advanced precision voltmeters, or special testing programs.

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 using AC power supply; For frames that require DC voltage, measure the DC voltage between the+24VDC and 0VDC terminals. If it is not a suitable AC or DC power source, the problem occurs outside of the PLC. If the AC or DC power supply voltage is normal, but the PWR light is not on, check the fuse, and if necessary, replace the CPU frame.
2. Is the PWR (power supply) light on? If it is on, check the displayed error code, compare it with the code definition in the error code table, and make corresponding corrections.
3. Is the RUN light on? If it does not light up, check if the programmer is in the PRG or LOAD position, or if there is a program error. If the RUN light is not on and the programmer is not plugged in, or if the programmer is in RUN mode and no error code is displayed, the CPU module needs to be replaced.
4. Is the BATT light on? If it is on, the lithium battery needs to be replaced. Due to the fact that the BATT light is only an alarm signal, even if the battery voltage is too low, the program may not have changed yet. After replacing the battery, check the program or have the PLC test run. If the program has errors, after completing system programming initialization, reload the program recorded on the tape into the PLC.
5. In a multi frame system, if the CPU is working, the RUN relay can be used to check the operation of several other power supplies. If the RUN relay is not closed (high resistance state), follow the first step mentioned above to check the AC or DC power supply. If the AC or DC power supply is normal and the relay is disconnected, the frame needs to be replaced.