Beckhoff First Scan Bit Direct

If your TwinCAT configuration utilizes running at different cycle times (e.g., a fast 1ms Motion Task and a slower 10ms Auxiliary Task), checking _TaskInfo[1].CycleCount in the slow task can cause issues if index 1 is mapped to the fast task.

In Beckhoff TwinCAT systems, there is no single global "S:FS" bit like those found in Rockwell (Allen-Bradley) controllers . Instead, users typically leverage the PlcTaskSystemInfo beckhoff first scan bit

bit may only trigger when the TwinCAT runtime is fully restarted, rather than just stopping and starting the PLC code execution via the developer interface. Initialization Importance If your TwinCAT configuration utilizes running at different

A common practice among developers is to manually declare a global variable that initializes as and is immediately set to after use. Structured Text Example: Copied to clipboard

Beckhoff's TwinCAT 3 environment offers multiple methods to implement a first scan, ranging from a simple, self-created flag to using the more official, built-in system structures.

IF _TaskInfo[GETCURTASKINDEXEX()].firstCycle THEN // Your initialization code here (e.g., setting default parameters) END_IF Use code with caution. Copied to clipboard