100/176 CANopen
Bosch Rexroth AG
, MIT: ID 40, 3 842 530 344/2014-05
9.9 PDO communication
PDO services support event-oriented data exchange with the SLK.
PDOs transmit the contents of
mapped
objects.
The SLK provides four PDOs for SLK
master (TPDO1 to TPDO4) and two PDOs for
master
SLK (RPDO1 and RPDO2). Each PDO can transmit 8 bytes of payload.
The primary application is TPDOs for event-oriented transmission of MDT data and
status messages. Note that all MDT objects in a TPDO together only activate one
trigger condition. If, e.g., 8 MDT data bytes are assigned to a TPDO, they are first all
read from the MDT and then entered together in the TPDO. Therefore only one TPDO
is sent.
By using RPDOs, it is also possible to run the ID 40 system with CANopen masters
that do not support command-oriented data exchange via SDOs.
However, be sure to observe the following restrictions:
1. The PDO default mappings in the SLK only provide access to the first six MDT
data bytes, the MDT status register and the “actual link state” and “commanded
link state” SLK register (see “PDO default mapping” in Chapter 9.9.1 “PDO
mapping”).
2. The recipient will not respond to PDO telegrams. This makes a PDO an
unconfirmed
CANopen service. The SLK saves the successful execution of a data
entry by an RPDO in the “error register” and “pre-defined error field” objects
(see 9.17.4 “Pre-defined error field [object 1003]”). These objects can only be
checked through additional access.
Fig. 30:
PDO Mapping
PDO Object
(virtual)
Useful data
Synchronization
Applikation
(CANopen
Master)
Object
Directory
MDT
PDO Communication
Parameters
PDO Status
PDO communication
PROOF COPy 1 | 20.05.2014 | FOR INTERNAL USE ONLy
