EtherCAT Real-Time Application Threads

Developing IgH Applications

6.5 Real-Time Thread Configuration

Real-time applications generally need to lock memory and increase the scheduling priority of the cyclic thread:

struct sched_param param = {
    .sched_priority = 80,
};

mlockall(MCL_CURRENT | MCL_FUTURE);
sched_setscheduler(0, SCHED_FIFO, &param);

The following practices are also recommended:

• Use absolute-time sleeps to prevent accumulated period drift.
• Complete memory allocation, file opening, and device initialization before entering the real-time loop.
• Avoid frequent printf() calls, dynamic memory allocation, or blocking I/O in the cyclic thread.
• Run logging, UI, and network services in non-real-time threads.
• Access only preallocated and correctly synchronized data from the cyclic thread.

Increasing the scheduling priority requires the appropriate permissions. Run as root, or configure the system to grant CAP_SYS_NICE and permission to lock memory.