CANopen
• 99
Network Communication
WAGO-I/O-SYSTEM 750
CANopen
4.3.3.3 Node Guarding Protocol
By means of Node Guarding, the NMT slave is cyclically requested via an
RTR frame to send its current status. Additional toggling of a bit detects
whether or not the NMT slave still operates correctly.
NMT Master
Node Guarding Protocol
NMT Slave
request
confimation
confimation
indication
Network Event
*
*
if guarding error
Node Event
*
indication
indication
response
response
.7
.7
Toggle-
Bit
Toggle-
Bit
Node State
Node State
.6
.6
.0
.0
request
indication
Remote
Frame
COB ID
0x700+Node ID
Remote
Frame
COB ID
0x700+Node ID
Fig. 4-16: Node Guarding Protocol
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4.3.3.4 Heartbeat Protocol
This protocol allows monitoring without RTR frames. A heartbeat generator
cyclically generates a heartbeat message received by n subscribers. The heart-
beat message contains the coding of the current generator status.
Heartbeat Producer
Heartbeat Protocol
Heartbeat Consumer
request
request
Heartbeat
Producer
Time
Heartbeat
Consumer
Time
Heartbeat
Event
indication(s)
indication(s)
indication
0 … 7 s
0 … 7 s
Fig. 4-17: Heartbeat Protocol
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