Beckhoff First Scan Bit [extra Quality] Today

For modern TwinCAT 3 development utilizing Object-Oriented Programming (OOP), using a simple boolean flag inside a Function Block (FB) is often inefficient. Instead, Beckhoff supports the implicit FB_init method. Implementation

When the TwinCAT runtime enters Run Mode, bInitialized is allocated memory and set to FALSE . The IF NOT bInitialized condition evaluates to TRUE . beckhoff first scan bit

Built-in FirstScan flag (recommended if provided) beckhoff first scan bit

A common pitfall: If you mark variables as RETAIN , they a warm start. But on a first scan (especially after download), you may want to override retain values. beckhoff first scan bit