Monitoring Discrepancy Error - Secure Input Group

What does FB MON Bit 2 mean?

A discrepancy has been detected between the 'Secure1' and 'Secure2' input channels in the FB MON function block. These inputs are used to switch off the evaluation of 'MonIn(x)' inputs. A discrepancy here means the redundant secure inputs are not in agreement, which can lead to unintended disabling of monitoring functions, potentially bypassing safety.

• Discrepancy between the 'Secure1' and 'Secure2' enable signals (e.g., from a mode selector switch) due to one signal being active and the other inactive.
• Faulty external device providing the 'Secure' signals, such as a mode selector switch with worn or damaged redundant contacts.
• Intermittent connection or wire break on one of the 'Secure' input lines (e.g., terminal X12.1 or X12.2).
• Incorrect configuration of the 'Secure' input type (e.g., NC vs NO) in the safety controller parameters (e.g., P_SECURE_INPUT_LOGIC).
• Unintended activation or deactivation of one 'Secure' input due to external wiring fault or component failure.

Click steps to track your progress.

1. 1

   Identify the external source of the 'Secure1' and 'Secure2' signals (e.g., key switch S_MODE) and test its redundant contacts for proper operation using a multimeter.

2. 2

   Measure the voltage potential on the 'Secure1' and 'Secure2' input terminals of the safety controller in both desired states (e.g., 24VDC when active, 0VDC when inactive).

3. 3

   Verify continuity of the wiring from the source device's redundant contacts to the safety controller's 'Secure1' and 'Secure2' input terminals.

4. 4

   Check the safety controller's parameter settings for the 'Secure Input Group' (e.g., P_MON_SECURE_TYPE, P_MON_SECURE_DEBOUNCE) to ensure they match the physical wiring and application.

5. 5

   Observe the diagnostic status of 'Secure1' and 'Secure2' inputs through the safety controller's software interface to determine which input is causing the discrepancy.