EtherCAT-Specific Variables

When an EtherCAT Master is configured, an EtherCAT Master task is added to the task configuration of the current application. As usual, a call for a POU can be added in the configuration of this task. EtherCAT-specific Boolean variables can be set in this POU to affect the action of the EtherCAT configuration within the application:

• Support for Optional Devices
• When the fieldbus is started, the lack of EtherCAT devices configured in the application generates an error that prevents the stack from loading. After setting the variables
• <instance name of EtherCAT master>.StartConfigWithLessDevice := TRUE;
• at the start of the first PLC cycle, missing devices are treated as optional devices and will no longer prevent the bus from starting correctly.
• Suppressing Transmission of Additional Messages
• The EtherCAT Master sends a message of its own for each individual task to update the outputs as quickly as possible. If, for example, an attached drive is synchronized with the real-time output data, the bus cycle task should be the only task permitted to set the outputs. Additional messages would disrupt the synchronization. To suppress additional task messages, set
• <instance name of EtherCAT master>.EnableTaskOutputMessage := FALSE;
• once in the first PLC cycle. Alternatively, the “Send/Receive per Task” option can be set in the “Master” tab of the EtherCAT Master.