8-30 
 
8-2-4 CANopen Protocol 
G2S CANopen contains the following protocols: 
NMT(Network Mangement Object) 
SDO(Service Data Object) 
PDO(Process Data Object ) 
Special function object 
 
Network management: used to activate network and monitor equipment (heartbeat, enable message). 
In network management, the same network only allows one master node and one or multiple slave nodes 
and follow the master-slave model. The equipment with network management master function is usually 
called CANopen master station and usually has SDO client functions. ON the contrary, the equipment 
with network management slave function is usually called CANopen slave station and must have PDO 
function. In this way, CANopen master station can control the slave station and read/write the object 
dictionary of CANopen slave station. 
 
Network management NMT 
1.  NTM service and protocol 
CANopen equipment activated and automatically enters pre-operation status after internal 
initialization. Then notify NMT master of this status change incident through Boot-up. The whole 
network will enter operation status when NMT master sends one CAN message. In addition, NMT 
master can force the equipment into prohibition status; all other communication services are prohibited 
except network management and heartbeat.