Communication Monitoring Services - Siemens MICROMASTER 420 Operating Instructions Manual

Data transfer using CANopen
3.2.2

Communication monitoring services

There are three communication monitoring services in CANopen:
• Node Guarding / Life Guarding
• Heartbeat
• Sync loss detection
Node Guarding:
MICROMASTER 420/430/440 supports Node Guarding and Life Guarding. With
Node Guarding, the CANopen master sends, to each slave, an RTR telegram with
the COB-ID 700H + node-ID. The slave responds, with the same COB-ID, with its
communications state. This means either Pre-Operational, Operational or Stopped.
Further, the message that is sent contains a toggle bit - using the Object Guard
Time, the time between two RTR messages, received at the slave, is set.
Life Guarding:
The CANopen slave monitors the incoming RTR messages from the master. The
number of RTR telegrams which can fail as a maximum before the slave initiates a
Life Guarding event is defined using the Life Time Factor object. The lifetime of the
master is calculated from the product of the Guard Time (refer to Node Guarding)
and Life Time Factor. This is the maximum time that the slave waits for an RTR
telegram (message) before it initiates a Life Guarding Event.
Node Node
Life Guard
time time
Node Guarding
Fig. 3-3 Node Guarding/ Life Guarding protocols
34
COB-ID = 700H + Node-ID
Request
Confirmation
COB-ID = 700H + Node-ID
Request
Confirmation
Event
Indication
Remote transmit request
7 6 ... 0
t s
Remote transmit request
7 6 ... 0
t s
CANopen Option Module
Issue 01/05
Indication
Response
Indication
Response
Life Guarding
Event
Indication
Operating Instructions
6SE6400-5BC00-0BP0