Two-Hand Sequence Violation

What does FB TWOHAND Bit 6 mean?

A specific two-hand error sequence violation has occurred: one input pair was actuated, and while waiting for the second, the first input pair was released before the second was actuated. This indicates an incorrect operating procedure or a 'teasing' attempt, which compromises the safety principle of simultaneous two-hand control and halts the machine.

• Operator prematurely releasing one two-hand button before the second button is actuated.
• A 'sticky' or slow-releasing button on one input pair causing a delayed deactivation signal.
• Contamination or mechanical obstruction preventing a button from maintaining its actuated state.
• Faulty internal spring or contact mechanism within one two-hand button leading to premature release.
• Excessive 'ReleaseTime' parameter (e.g., P_TwoHandReleaseTime) in the safety function block configuration.

Click steps to track your progress.

1. 1

   1. Retrain the operator on the required sequence: both buttons must be actuated and held simultaneously until the machine cycle begins, and neither released prematurely.

2. 2

   2. Press and release each two-hand button multiple times, observing its mechanical return for any sticking or sluggishness.

3. 3

   3. With power off, use compressed air to clean around the button actuators and inspect for any physical debris preventing full travel.

4. 4

   4. Isolate the suspected button assembly and use a multimeter to test its normally open (NO) contacts for consistent closure and opening without chatter.

5. 5

   5. Review the safety controller configuration for the 'TwoHandReleaseTime' parameter; ensure it is set appropriately (e.g., 50ms) to detect premature release.