Beckhoff First: Scan Bit

VAR bFirstScan : BOOL := TRUE; // Initialized to TRUE END_VAR

In this example, the initialization code is executed only once, during the first scan of the PLC, when the First Scan Bit is set. beckhoff first scan bit

During the first cycle, the IF bFirstScan condition evaluates to true. The initialization code executes. bFirstScan is set to FALSE at the end of the block. VAR bFirstScan : BOOL := TRUE; // Initialized

IF fbFirstScan() AND (nEtherCATState = 8) THEN // 8 = OP EnableOutputs(); END_IF VAR bFirstScan : BOOL := TRUE