Safe torque off 1

What does FA81 mean?

Safe Torque Off (STO) signal 1 has been lost or is not correctly applied. This fault often occurs in conjunction with 5091 (if running) or A5A0 (if stopped) and signifies a problem with one leg of the dual-channel STO safety circuit. This compromise of the STO function prevents safe operation.

Additional Steps

Steps 1–2 are listed in Priority Fix.

1. 3

   Ensure that any external STO activation affecting signal 1 is intentional and cleared if not.

2. 4

   Reset any associated faults or warnings (5091, A5A0) after restoring STO signal 1.