CANopen Communication
FC5101 and FC5102
47
Version: 2.0
Fig. 39: Diagram: CAN "SYNC" telegram
PDO transmission types: Parameterization
The PDO transmission type parameter specifies how the transmission of the PDO is triggered, or how
received PDOs are handled.
Transmission type Cyclical
Acyclical
Synchronous
Asynchronous Only RTR
0
X
X
1-240
X
X
241-251
- reserved -
252
X
X
253
X
X
254, 255
X
The type of transmission is parameterized for RxPDOs in the objects at 0x1400ff, sub-index 2, and for
TxPDOs in the objects at 0x1800ff, sub-index 2.
Acyclic Synchronous
PDOs of transmission type 0 function synchronously, but not cyclically. An RxPDO is only evaluated after the
next SYNC telegram has been received. In this way, for instance, axis groups can be given new target
positions one after another, but these positions only become valid at the next SYNC - without the need to be
constantly outputting reference points. A device whose TxPDO is configured for transmission type 0 acquires
its input data when it receives the SYNC (synchronous process image) and then transmits it if the data
correspond to an event (such as a change in input) having occurred. Transmission type 0 thus combines
transmission for reasons that are event driven with a time for transmission (and, as far as possible, sampling)
and processing given by the reception of "SYNC".
Cyclic Synchronous
In transmission types 1-240 the PDO is transmitted cyclically: after every ”nth" SYNC (n = 1...240). Since
transmission types can be combined on a device as well as in the network, it is possible, for example, for a
fast cycle to be agreed for digital inputs (n = 1), whereas the data for analog inputs is transmitted in a slower
