Failure Monitoring; Nodeguarding/Lifeguarding; Heartbeat; Cob Ids - Kübler IS60 Handbuch

6.6 Failure monitoring

Failure monitoring functions Heartbeat, as well as Nodeguarding / Lifeguarding are available
because the nodes in a CANopen network with event-driven transmission do not respond on a regu-
lar basis. Only one of two monitoring methods can be used.
6.6.1 Nodeguarding / Lifeguarding
Nodeguarding describes the monitoring of one or more nodes by the NMT master. For this purpose,
the NMT master periodically sends a RTR telegram to the slave to be monitored which will respond
with a status or a toggle Bit. If the status or toggle Bit do not correspond to the one the guarding
master expects to receive or if no response is sent, the master assumes an error by the slave.
With the help of this mechanism the node to be monitored is able to also recognize when the guard-
ing master fails. Here, two parameters are used. The interval time the guarding master uses to send
a request to the inclinometer to be monitored is the "guard time" (100CH). A second parameter, the
"Life Time Factor" (100Dh) defines a multiplicator after which the connection is regarded as being
interrupted. This time interval is described as lifetime of the node ("Node Lifetime").
"Node Lifetime" = "Guard Time" × "Lifetime Factor"
In case the inclinometer does not receive a guarding request from the master during this parameter-
ized time interval, it assumes that the master has failed, sends an emergency telegram and resets to
the "pre-operational" status. In case one of both parameters is "0" (default setting), monitoring of the
master will occur (no lifeguarding).

6.6.2 Heartbeat

Heartbeat is a failure monitoring mechanism which functions without RTR telegrams.
For this purpose the inclinometer cyclically sends a Heartbeat message which contains the status of
the device. The master is able to monitor these telegrams. Heartbeat is activated as soon as
a value greater than "0" is entered into the register Heartbeat Interval Time (1017h).
Note
Heartbeat significantly impacts the busload of the CANopen network, but only creates half the load
compared to Nodeguarding / Lifeguarding.

6.7 COB IDs

The CAN identifiers of the communication objects are set according to the predefined connection set
at each reset (communication, application and hardware reset) depending on the preset Node ID
(2000h). Table 10 displays the basis for calculation and the standard values (Node ID = 10).
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