Schneider Electric IP67 manual Synchronous, RTR mode, Asynchronous

CANopen Network Interface

Synchronous For certain applications, synchronization between scanning of the inputs and (mode 0 to 240) activation of the outputs may be necessary.

For this reason, CANopen provides the "SYNC" object, a high-priority CAN message without any working data, which, when it is received by the synchronized devices is used to trigger the reading of inputs or activation of outputs (Trigger).

The following diagram shows the time data for synchronized PDO transmission. Communication cycle

SYNC SYNC SYNC

Current input data

Set point

Output

Data

Input search in each SYNC message

Actuation based on outputs at next SYNC message

Synchronous window length

Synchronous	Aside from polling by request ("timing-related polling"), the slaves can also be polled
RTR (mode 252)	by the master by using data request messages ("Remote-Frames", known as RTR
	messages).
	In mode 252, the device uses the synchronization message to trigger transmission
	of the PDO once it has received the RTR message.
Asynchronous
	In mode 253, the TPDOs are transmitted once the RTR message is received.
RTR (mode 253)

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