Internal Terminal Error (μC2)

What does Diag3:lit, Diag4:off mean?

This LED combination (Diag 3 lit, Diag 4 off) indicates an internal error related to microcontroller 2 (μC2) of the terminal. This is a global fault, leading to the shutdown of the terminal. Similar to μC1 errors, these faults typically require inspection by the manufacturer.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Access the TwinCAT System Manager to check for any additional diagnostic messages or system events logged by the EL6900 prior to the shutdown.