System startup fault: PPU black screen, no display

What does PPU Black Screen mean?

The control system cannot start up successfully after power-on. The PPU normally shows a black screen with no display at all, indicating a startup failure.

• CF card not properly inserted
• Status LED on PPU is off, indicating no 24 VDC power supply
• Loose connection at PPU power supply interface (X1)
• Damaged PPU

Click steps to track your progress.

1. 1

   Check the status LED on the PPU panel. If it is lit, power off the control system, check if the CF card is properly inserted, then power on again.

2. 2

   If the status LED is off, check the power supply interface (X1) on the back of the PPU for loose connections or if the 24 V terminal matches the interface.

3. 3

   Use a multimeter to measure and verify that a 24 VDC power supply is available at interface X1.

4. 4

   If the fault still exists after these operations, professional replacement and maintenance are necessary as the PPU is likely damaged.