Internal Data Bus Communication Error (Unidentified Module)

What does -- mean?

An internal data bus communication error has occurred, and the system is unable to pinpoint the specific defective I/O module. This fault may stem from a faulty power supply module for the I/O or a defective I/O module itself. The I/O LED will likely flash red.

• Defective power supply module (e.g., 750-602) for the I/O system
• Internal data bus communication failure due to a defective I/O module
• Corrupted data transmission on the internal data bus

Click steps to track your progress.

1. 1

   Verify the proper functioning of any connected power supply modules (e.g., 750-602) by checking their LED signaling as per the 'LED Signaling' section.

2. 2

   If the power supply module functions properly, switch off the power supply to the system.

3. 3

   Perform a bisection method to isolate the defective I/O module: Place the end module in the middle of the I/O modules and power on. If the I/O LED continues to flash red, repeat the process on the first half (towards the controller). If the LED is no longer flashing, repeat on the second half (away from the controller).

4. 4

   If, after isolating to a single I/O module, the LED still flashes, replace that I/O module. If the issue persists, the controller's internal data bus interface may be defective, requiring controller replacement.