Beckhoff First Scan Bit File

With TwinCAT 3, Beckhoff introduced the Tc3_Standard library, which includes a dedicated function block: F_TRIG combined with a system flag is no longer needed. Instead, use:

), Beckhoff provides this functionality primarily through the PLC System Information PLC_STARTUP In a typical TwinCAT project, developers often use the PlcTaskSystemInfo structure. By accessing the bFirstCycle beckhoff first scan bit

The FB_FirstScan function block monitors the system’s cycle counter and reliably returns TRUE for exactly one cycle after application start, even if multiple programs call the same FB instance. With TwinCAT 3