Old text backup: The function and use of sync in CANopen

Sync is a method of CANopen to manage the synchronous data receiving and dispatching of each node, which is equivalent to the network beats, and the synchronized PDO performs real-time data transmission according to this network beat. Sync belongs to the production/consumption mode of communication, there is only one sync producer in the network, there are generally many consumers, whose network identifier is high priority, generally set to 0x80, basically except the NMT priority is highest. The sync producer sends the sync message at a fixed frequency, requires the Sync node (consumer) to receive and count it, and when the count reaches the corresponding TPDO requirement of the node, the Tpdo mapped data is sent (depending on the PDO transfer type, which may also be the mapping Data Update). In this process, the Sync producer provides network beats, and each consumer performs a data transfer function in multiples of the cycle.

The following points should be noted in applying sync to the CANopen network:

1. Sync is not the main node must be the function, not necessarily and NMT on the same node, the actual network application in the network can find a task less, real-time good node to be a sync producer, sync consumer can have multiple, but the producer can only have one existence.
2. Sync is without data to make the message as short as possible in order to speed up its transmission and reduce network occupancy.
3. After sync is issued, the PDO that needs to send the data sends the data within the specified time period, which is called the time window (object 1006H specified), which is less than the sync cycle, so that each cycle has a certain amount of time for other types of network traffic.

Old text backup: The function and use of sync in CANopen