Degraded Mode

@Updated D1

When fieldbus communication with the controller is lost, TeSys island remains in the operational state however, enters Degraded mode. Communication loss is defined by:

EtherNet/IP fieldbus: Communication loss is detected when an established exclusive owner connection times out for the duration specified by the communication loss timeout setting in DTM.
Modbus/TCP fieldbus: Communication loss is detected after receiving no write requests to the cyclic I/O scanning data for the duration specified by the Communication Loss Timeout setting in the DTM.
PROFINET fieldbus: Communication loss is detected when an established application relation (AR) with an I/O controller is closed or disconnected on either end of the AR for the duration specified by the communication loss timeout setting in DTM. TeSys island supports one AR per I/O controller.
PROFIBUS-DP fieldbus: Communication loss is detected when the duration specified by the communication loss timeout setting in DTM for the connection expires.

NOTE: Loss of communication with the DTM or OMT does not trigger the transition to Degraded mode.

During Degraded mode:

The Fieldbus ports remains active.
The Service port remains active.
The TeSys avatars enter Degraded mode. During Degraded mode, avatars with local control are driven by local inputs. All other avatars enter Fallback configured. For the definition of Fallback Mode, refer section System States.