Supply Voltage or Internal Temperature Out of Range

What does Diag3:off, Diag4:steady_lit mean?

This diagnostic LED state (Diag 3 off, Diag 4 steadily lit) indicates that either the supply voltage to the terminal or its internal temperature is outside the permissible operating range. More detailed information can be found by examining the diagnostic object FA00hex. This condition can lead to system instability, unreliable operation, or terminal shutdown.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Verify the ambient temperature around the EL6900 terminal to ensure it is within specified limits, checking for any localized heat sources or obstructions.

2. 4

   Inspect the EL6900 terminal and its immediate surroundings for proper ventilation and clear airflow paths.