Process Data Objects (Pdo) - Beckhoff EL6751 Documentation

SDO Explanation
Monitoring the
synchronous
TxPDOs
Monitoring the
asynchronous
TxPDOs
Error response
Manual network management
The CANopen state (STOPPED, PRE-OPERATIONAL, OPERATIONAL) of a CANopen slave can be
changed via ADS write control. In this case the AMS address should be set as for SDO communication. The
other parameter are listed in the following table:
ADS State
ADSSTATE_RUN (5)
ADSSTATE_RUN (5)
ADSSTATE_STOP (6) 0
ADSSTATE_RUN (5)
ADSSTATE_RUN (5)
ADSSTATE_STOP (6) 0
ADSSTATE_RUN (5)
5.4.3

Process Data Objects (PDO)

Introduction
In many fieldbus systems the entire process image is continuously transferred - usually in a more or less
cyclic manner. CANopen is not limited to this communication principle, since the multi-master bus access
protocol allows CAN to offer other methods. Under CANopen the process data is not transferred in a master/
slave procedure, but follows instead the producer-consumer model. In this model, a bus node transmits its
EL6751
Device State
0
1
1
3
2
Version: 3.5
Parameterization and commissioning
Option
Monitoring of the synchronous TxPDOs commences
when they were received for the first time. If the
transmission type is set to 1, this TxPDO must be
received in the SYNC cycle, otherwise the node state
switches to 40 or 22 and the CANopen slave is treated
according to configured error response. The time slot
ends after the input shift time has elapsed (EL6751, with
a SYNC multiplier greater than 1 the input shift time in the
last EtherCAT cycle counts before the next SYNC cycle
commences) or once all synchronous RxPDOs were sent
(FC51xx, CX1500-M510). The monitoring can be made
less strict by setting an event time not equal 0 in the
corresponding TxPDO. In this case the CANopen master
is tolerant for one SYNC cycle, i.e. the node state is not
set to 22 until the TxPDO has failed twice in succession.
For transmission types greater than 1 the CANopen
master is also tolerant for one cycle before a fault is
detected and the node state is set to 22.
Monitoring of the asynchronous TxPDOs is only active if
their event time is configured with greater than 0 and
commences when they are received for the first time. If
the TxPDO is not received within twice the event time, the
node state is set to 22 and the CANopen slave is treated
according to the configured error response.
If a fault is detected in a CANopen slave during TxPDO
monitoring or during guarding/heartbeat, the node state
switches to a value not equal 0 and configured error
response is triggered (according to tab BK51x0 [} 86] or
CAN node [} 88]). In the default setting the CANopen
slave is stopped and then restarted (with communication
reset).
CANopen state transition
OP->PREOP
PREOP->OP
OP->STOP
STOP->OP (with communication reset)
STOP->OP (without communication reset)
PREOP->STOP
STOP->PREOP (without communication reset)
101