EtherCAT Cyclic Application
Developing IgH Applications
6.3 Basic Structure of a Cyclic Task
The following simplified call sequence illustrates how the master API is used:
while (running) {
clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME,
&wakeup_time, NULL);
ecrt_master_receive(master);
ecrt_domain_process(domain);
/* Read inputs from domain_pd with EC_READ_*(). */
/* Run the device state machine and control algorithm. */
/* Write outputs to domain_pd with EC_WRITE_*(). */
ecrt_domain_queue(domain);
ecrt_master_send(master);
}When using DC, set the application time and synchronize the clocks at the correct point in the cycle:
ecrt_master_application_time(master, app_time_ns);
ecrt_master_sync_reference_clock_to(master, app_time_ns);
ecrt_master_sync_slave_clocks(master);The specific synchronization method depends on the reference clock, slave capabilities, and control period. Refer to the IgH API documentation and slave manual.
6.4 Building an Application
If IgH is installed in /opt/etherlab:
gcc main.c -o ethercat_app \
-I/opt/etherlab/include \
-L/opt/etherlab/lib \
-Wl,-rpath,/opt/etherlab/lib \
-lethercat -lpthreadFor cross-compilation, use the target platform compiler and ensure that the headers and libethercat.so come from the same IgH build.