Process Data Objects (Pdo) - Siemens Simatic Operating Instructions Manual

4.1.1.3

Process data objects (PDO)

Process data objects
Process data are transmitted on the CANopen side by means of PDOs.
The PN/CAN LINK supports 512 PDOs for transmitting/receiving.
One entry exists in the OD for the "Communication parameters" and one entry for the
"Mapping parameters" for each receive PDO (RX-PDO) and each transmit PDO (TX-PDO).
In the configuration you specify:
● The COB ID of the CAN message
● The transmission type (synchronous/event-controlled)
● Whether or not the PDO is active
● The OD entries onto which the transmitted or received PDOs are mapped
Transmission types
The PN/CAN LINK supports the following PDO transmission types:
Transmission method
Acyclic synchronous
Cyclic synchronous
RTR only
Manufacturer-specific event control
Application-specific event control
SIMATIC PN/CAN LINK
Operating Instructions, 03/2018, A5E39895388-AB
Description
PDO is transmitted during the next "SYNC" after a value
change
Depending on the configuration, PDO is transmitted for each
first to 240th "SYNC" regardless of value changes
On request only (RTR message synchronous / asynchronous)
PDO is only transmitted after a RTR message with the COB
ID of the PDO was received. The PN/CAN LINK only supports
transmission method "RTR only" for transmit PDOs and not
for receive PDOs.
These transmission types are event-controlled (asynchro-
nous).
PDO is transmitted following an event, that is a value change,
as well as after expiration of a configured timeout, regardless
of "SYNC".
Event-controlled transmit-PDOs with transmission type 255
(device-profile specific / and application-profile specific) are
also transmitted during transition to the NMT state "Opera-
tional".
Functions
4.1 CANopen
21