Operation mode (trigger mode)

Trigger via the communication cycle, i.e. frame-triggered:

"FreeRun/SM-synchron"
As soon as an EtherCAT communication addresses the EJ5021 EtherCAT plug-in module, it starts a new position determination. The EtherCAT communication is usually started by the PLC/NC task.

Operation mode (trigger mode) 1:
Frame-triggered EtherCAT communication

Trigger via the module's own distributed clock:

  1. "DC-synchron (input based)"
    The DC unit of the module triggers the position determination shortly before the next collecting EtherCAT telegram, so that the most up-to-date possible value is available for collection.
  2. "DC-synchron"
    In the setting "DC-synchron" the EJ5021 module is operated in the DC group of the output modules, whereby it does not determine the position shortly before an EtherCAT communication, but shortly after the communication.
    As a result, the data are significantly older.
Operation mode (trigger mode) 2:
DC synchron (input based) triggered EtherCAT communication

The exact DC time of the position determination is not output as process data by the EJ5021 module. It can be set via Advanced settings of the module or for all modules via Advanced settings of the EtherCAT master (see following figures). These values are calculated once during the creation/activation of the configuration and do not change any further during runtime.

Operation mode (trigger mode) 3:
Advanced settings of the EtherCAT plug-in module in TwinCAT System Manager
Operation mode (trigger mode) 4:
Advanced settings of the EtherCAT master in the TwinCAT System Manager

The determination of the current position is subject to a constant delay of several µs. This delay is already accounted for in TwinCAT with the calculation of the InputShiftTime, so that the actual determination time and the calculated time coincide with each other.

The minimum possible sampling rate of the EtherCAT plug-in module EJ5021 is 80 µs and thus also the minimum possible EtherCAT cycle time.