Data Transmission Types - Siemens Sinamics S120 Commissioning Manual

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2.7 PDO (Process Data Object)
A maximum of 8 RPDO and 8 TPDO can be configured per logical CANopen device module.
The object index range for each additional drive can be determined using r8743. The
parameter value corresponds to the drive object ID. The parameter index corresponds to the
factor with which the offset 40 hex must be multiplied and added to the basis object. For
instance, the drive starts with offset factor 1 from 1640 hex.
The indices of the corresponding entries in the object directory are calculated as follows:
● RPDO communication parameter index = 1400 hex + offset factor 40 hex
● RPDO mapping parameter index = 1600 hex + offset factor 40 hex
● TPDO communication parameter index = 1800 hex + offset factor 40 hex
● TPDO mapping parameter index = 1A00 hex + offset factor 40 hex
2.7.2

Data transmission types

The following PDO transmission types are available:
● Synchronous transmission
● Asynchronous transmission
In order that the communicating devices remain synchronized during transmission, a
synchronization object (SYNC object) must be transmitted at periodic intervals.
The following diagram shows the principle of synchronous and asynchronous transmission:
Figure 2-8
The type of transmission is characterized by a PDO's parameter for transmission type.
For synchronous TPDOs, the transmission type also identifies the transmission rate as a
factor of the SYNC object "transmission intervals". Here, the transmission type "1" means
that the message will be transmitted in every SYNC object cycle. The transmission type "n"
means that the message will be transmitted in every nth SYNC object cycle.
Asynchronous TPDOs are transmitted without reference to the SYNC signal. Data from
synchronous RPDOs, which are received after a SYNC signal, is not transmitted to the
application until after the next SYNC signal.
68
Principle of synchronous and asynchronous transmission
Commissioning Manual, 11/2017, 6SL3097-4AA00-0BP3
CANopen interface