Interruption Of The Data Transmission Path - Leuze electronic DDLS 200 Technical Description

DeviceNet / CANopen
9.6

Interruption of the data transmission path

Response upon interruption of the optical data transmission path
Segment 1 Segment 2
Interruption of the optical data
transmission path
DT1 DT2
TN1 TN4
TN2 TN3
Figure 9.12: Interruption of the optical data transmission path
If only data fragments are received as the result of the interruption in the optical transmission path,
these are detected and are not transmitted to the CAN bus segment. The connected subscribers are
not informed of an interruption in the optical transmission path via the protocol (switching output is ac-
tivated). Data transmitted during the interruption are lost. The primary protocol is responsible for man-
agement of the subscribers. For this reason, the monitoring mechanisms of the primary protocol
should be used (Node/Life Guarding, Heartbeat, ...).
"Monitoring" of subscribers
If a DDLS 200 optical data transmission system is used in a DeviceNet or CANopen system, it is ben-
eficial to monitor all subscribers to determine whether they are still participating in data exchange. The
following mechanisms are available for this purpose:
Heartbeat
Subscribers transmit cyclical heartbeat messages. If a message is not received for a certain period of
time, this is detected by the connected subscribers as a "Heartbeat Error".
Node / Life Guarding (CANopen)
The NMT Master (Network Management Master) cyclically queries all subscribers and expects an an-
swer within a certain period of time. If this response is not received, a "Guarding Error" is detected.
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