Beckhoff EL6731 Documentation page 162

EtherCAT communication EL6731-00x0
PDO Mapping
There is an EtherCAT RxPDO (if the DP slave has DP inputs (is sent to the DP master)) and an EtherCAT
TxPDO (if the DP slave has DP outputs (is received from the DP master)). The PDO mapping of the
EtherCAT PDOs is automatically calculated by the EL6731-0010 after the download of the respective 0x8yyz
objects and can be read. The PDO mapping objects can only be written with the values that the
EL6731-0010 has calculated itself. The writing of the PDO mapping thus serves only to check the PDO
mapping calculated by the EtherCAT configurator and can therefore be omitted.
PDO Assign
Additionally there is an EtherCAT PDO that contains status information. This PDO is selected via the PDO
Assign. With regard to the order of the PDOs in the PDO Assign, it is important to ensure that the index of
the assigned EtherCAT PDO increases with each entry in the corresponding PDO Assign object. If the
EtherCAT master does not transfer a PDO Assign to the StartUp SDOs, then the PDO 0x1A7F [} 167] is
assigned for the status.
Cyclic DP communication
During the transition to SAFEOP, the EL6731 checks the length configured in the Sync Manager channels 2
and 3 against the length calculated from PDO Mapping and PDO Assign. The SAFEOP state is only adopted
if these lengths match. The DP function of the EL6731-0010 is active in the SAFEOP state. As long as the
EL6731-0010 is in SAFEOP, the DP input data that are sent to the DP-master are set to 0. As soon as the
EL6731-0010 has been switched to OP, the data from the EtherCAT outputs are transmitted to the DP
master.
The EL6731-0010 runs independently of the EtherCAT cycle.
Configuration of the EL6731-0010 with Backup Parameter Storage
The following flow chart shows the sequence of the configuration of the EL6731-0010 with Backup
Parameter Storage:
162 Version: 2.8 EL6731