This is the third in a series of posts that will cover various topics concerning the operation of PRIMUS’ Pri-Matic® PSS9 control system.

There are certain circumstances that may cause the Allen-Bradley 1400 MicroLogixTM Programmable Logic Controller (PLC), to generate a major fault. This includes a power interruption or the rare case of an input being sufficiently out of range.

If a major fault has occurred, a red FAULT LED will be flashing on the MicroLogix’s status panel. The PLC will stop operation until the fault is cleared.

Clearing the Fault

Clearing the fault is a simple operation which can be performed using the keypad controls on the PLC. To access the MicroLogixTM 1400 PLC, the control box must be opened. The PLC should look like Figure 1 below:

Figure 1 MicroLogixTM 1400 1766-L32BWAA PLC

Figures 2 – 3 lists the various controls used to perform these steps along with some reference information about how the keypad works and what functions the various keys perform.

Operating Buttons

Figure 2 Keypad Operating Buttons Functions

Using Menus to Choose Values

Figure 3 Keypad Operating Buttons for Menu Selection

Figure 4 shows the Controller Status LED panel in greater detail. Figure 5 is a reference table showing what each status LED represents.

Figure 4 Controller Status LED Indicators

Controller LED Indicators

Figure 5 LCD Status LED Indicators

The FAULT LED indicates when the controller has entered a major fault condition. This will automatically cause the PLC to stop operations until the fault is cleared. The most common fault encountered will be an application fault, which is indicated by a flashing red LED.

To clear an application fault, follow the steps listed below:

  1. The LCD I/O Status screen is the default screen normally showing (refer to Figure 6 I/O Status Screen).

Figure 6 I/O Status Screen

  1. Select the “ESC” button and press it once. The LCD screen should change to show the Main Menu screen (refer to Figure 7 LCD Main Menu Screen 1).

Figure 7 LCD Main Menu Screen 1

  1. On the Main Menu screen, select the Mode Switch by using the Up and Down keys on the LCD keypad. Move the cursor until it points at the Mode Switch label as shown in Figure 8.

Figure 8 LCD Main Menu Screen 1

  1. Press the OK button to select the Mode Switch option. The LCD screen with change to show Figure 9.

Figure 9 LCD Mode Screen

  1. When the Up or Down key is pressed, the mode indicated by the cursor starts to blink if the mode is different from the current mode of the controller.
  2. Using the Up or Down keys, place the cursor on the Program mode. Press the OK key to select the mode indicated by the arrow.
  3. Using the Up or Down keys, place the cursor on the Run mode. Press the OK key to select the mode indicated by the arrow.
  4. Repeat Steps 4 and 5, leaving the mode switch in the RUN position. The FAULT LED should no longer be illuminated indicating the fault is cleared.
  5. Return to the Main Menu screen by using the ESC key

Close the control box and resume normal operations. If the fault is cleared, but the controls do not respond, re-initialize the system by shutting Off the control box with the large yellow toggle switch. Wait 30 seconds and turn the control box back On.

Questions and Comments

Have a question or having difficulties? Talk to Dave Schall, our PRIMUS sterilizer expert who is here to assist you anytime at 877.679.7800 extension 1212 or email at dschall@spire-is.com.

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