JUMO 902910 CANtrans T RTD Temperature Probe with CANopen Output Operating Instructions - Manual (Page 21)

21
5 CANopen function
5.8 Node Guarding
The Node Guarding object provides an alternative to the Heartbeat object (see
chapter 5.7 “Heartbeat”, page 20).
It indicates the presence of a transmitter, thereby ensuring system reliability.
Unlike Heartbeat, in the case of Node Guarding the NMT master (usually a
PLC) sends a request, which is answered by the NMT slave (here: the
CANtrans transmitter).
The structure of the Node Guarding response is similar to that of the Heartbeat
protocol. The only difference is that it contains an additional toggle bit that
changes between 0 and 1 for consecutive messages.
s: status of the NMT slave
4: STOPPED
5: OPERATIONAL
127: PREOPERATIONAL
t: toggle bit
Node Guarding
user data The Node Guarding message contains one byte, consisting of the toggle bit t
and the NMT status s, which is coded as follows:
Bootup: 0
Stopped: 4
Operational: 5
Preoperational: 127