Ethercat Slave Process Data Settings (Pdo) - Beckhoff EP3356-0022 Documentation

Commissioning/Configuration
6.3

EtherCAT slave process data settings (PDO)

The process data transferred by an EtherCAT slave during each cycle (Process Data Objects, PDOs) are
user data which the application expects to be updated cyclically or which are sent to the slave. To this end
the EtherCAT master (Beckhoff TwinCAT) parameterizes each EtherCAT slave during the start-up phase to
define which process data (size in bits/bytes, source location, transmission type) it wants to transfer to or
from this slave. Incorrect configuration can prevent successful start-up of the slave.
For Beckhoff EtherCAT EL/ES/EP slaves the following applies in general:
• The input/output process data supported by the device are defined by the manufacturer in the ESI/XML
description. The TwinCAT EtherCAT Master uses the ESI description to configure the slave correctly.
• The process data can be modified in the system manager. See the device documentation. Examples of
modifications include: Mask out a channel, displaying additional cyclic information, 16-bit display
instead of 8-bit data size, etc.
• In so-called "intelligent" EtherCAT devices the process data information is also stored in the CoE
directory. Any changes in the CoE directory that lead to different PDO settings prevent successful
startup of the slave. It is not advisable to deviate from the designated process data, because the
device firmware (if available) is adapted to these PDO combinations.
If the device documentation envisages modification of process data, proceed as follows (see illustration
below).
• A: Select the device to configure
• B: In the "Process Data" tab select Input or Output under SyncManager (C)
• D: The PDOs can be selected or deselected
• H: The new process data are visible as linkable variables in the system manager. The new process
data are active once the configuration has been activated and TwinCAT has been restarted (or the
EtherCAT master has been restarted)
• E: If a slave supports this, Input and Output PDO can be modified simultaneously by selecting a so-
called PDO record ("predefined PDO settings").
Fig. 54: Configuring the process data
58 Version: 1.1.0 EP3356-0022