(* Logic Section ) IF bFirstScan THEN ( --- This runs ONLY on the first scan --- ) nCounter := 0; ( Reset variables ) ( Perform other startup routines *)
The difference between a and a warm start in relation to this bit. Beckhoff CX1010 first scan | PLCtalk - Interactive Q & A beckhoff first scan bit
: The INIT section runs before the first cyclic scan. This is actually earlier than a typical "first scan bit." If you need to guarantee initialization occurs before any other logic, INIT is superior. (* Logic Section ) IF bFirstScan THEN (
: Triggering handshake or connection logic that only needs to happen once upon startup. Safety Resets : Triggering handshake or connection logic that only
This distinction is crucial for:
The Beckhoff First Scan bit is a small, easily overlooked tool that separates professional, robust PLC code from fragile, “works-most-of-the-time” logic. By taking explicit control of the first cycle, you eliminate startup surprises, protect hardware, and ensure your TwinCAT application starts every time in a predictable, safe state.