EtherCAT Editor: MainDevice Tab

To access this window: In the EtherCAT Editor, in the EtherCAT Explorer pane, click the EtherCAT MainDevice in the list, then select the MainDevice tab.

The MainDevice tab provides the following configuration options:

General

Cycle Time

The Cycle Time matches the RMC’s Loop Time and is not configurable on this tab.

Cable Redundancy

Enable or disable cable redundancy.

If redundancy is enabled, the Out port of the last device in the EtherCAT network must be connected to the ECAT2 port on the RMC EtherCAT module.

If redundancy is disabled, the ECAT2 port must not be connected.

Performance Measurement

Enable or disable performance management. When enabled, the EtherCAT Diagnostics Performance tab will display the times of various EtherCAT processes.

Startup State

Specify the Startup State. Typically, this is Op mode.

To change the mode after the network starts up, write to the ECAT MainDevice Target State register.

Fault Recovery Mode

This defines the behavior after the network faults.

Disabled: No automatic attempt will be made to restart the network.
Restart Cyclic: The RMC will attempt to restart the network by transitioning it to Pre-Op. If the transition to Pre-Op is successful, the RMC will transition to the Target Master State (typically Op). This option is useful when a user wants the EtherCAT network to automatically return to Op state after a slave is power-cycled or disconnected/reconnected on the network. Transitioning to Pre-Op allows the network to recover from most errors.

Cyclic Timing

The Cyclic Timing section defines the points in the RMC’s control loop at which the cyclic EtherCAT data is sent on the network and which the EtherCAT data that has been received from the network is expected to have been processed.

For most applications, the default cyclic timing settings should work. For applications with a large number of axes, more processing time may be required in the control loop before the data is ready to be sent over EtherCAT. In this case, the Cyclic Send Offset may need to be increased. If the Cyclic Send Offset is increased, the Cyclic Receive Offset may possibly also need to be increased.

Cyclic Send Offset

The Cyclic Send Offset specifies the point in the control loop at which the cyclic EtherCAT send is scheduled. This is specified as a percentage of the control loop. The default value is 45% and the range is 30% to 60%.

Cyclic Receive Offset

The Cyclic Receive Offset specifies the point in the control loop at which the cyclic EtherCAT response is processed. This is specified as a percentage of the control loop. The default value is 80% and the range is 70% to 90%.

Details – Cyclic Send and Receive

This diagram of the RMC’s control loop illustrates where the where the Cyclic Send Offset and Cyclic Receive Offset apply. The motion processing is performed at the beginning of the control loop. The motion processing consists of receiving and processing the feedback, calculating the motion target profiles, calculating the PIDs, and then outputting the Control Output signal.

The motion processing must be complete before the EtherCAT frame is sent out. Similarly, the EtherCAT data that has been received when the frame returns must have its receiving processing completed some time before the end of the control loop, so that the data is ready for the ‘Read Feedback’ at the beginning of the control loop.

Errors– Cyclic Send and Receive

Event Log error	Cause	Effect	Fix
EtherCAT cyclic output data was not ready in time.	Motion processing not complete before the EtherCAT frame is sent	Output data delayed one loop	Increase Cyclic Send Offset (may require increasing Cyclic Receive Offset)
EtherCAT cyclic frame was not received back in time.	Frame not returned via EtherCAT before the Cyclic Receive Offset	EtherCAT data marked invalid*	Increase Cyclic Receive Offset, reduce Cyclic Send Offset, increase control loop time, or reduce EtherCAT data
EtherCAT cyclic input data was not received in time.	Returned data not fully processed before feedback is read	EtherCAT data marked invalid*	Reduce Cyclic Receive Offset, increase control loop time, or reduce EtherCAT data

*For axes using the EtherCAT data as feedback, the No Transducer bit is set once the accumulated failure count reaches 5. The count increases by 1 each time either error occurs and decreases by 1 each time the data is successfully processed, never going below 0.

For more details, see EtherCAT Troubleshooting.