Need Help In Understanding how PLC will scan this.

I'm trying to understand how the PLC will scan this "For" loop.

will the "PhoneNb" variable not increment until all instructions within the "For" - "End_For" are complete? Or how will it scan this? Ton_4 is 3 seconds and Ton_5 & 6 are 1 second timers.


if FBEN THEN

For PhoneNb := 1 to 2 DO

TON_4(AWT_4.Q, Time2); R_TRIG_8(TON_4.Q); AWT_4(R_TRIG_8.Q, TextModeEnable, EnableTextMode);
TON_5(AWT_5.Q, Time1); R_TRIG_9(TON_5.Q); AWT_5(R_TRIG_9.Q, PhoneChannel, PhoneNumber[PhoneNb]);
TON_6(AWT_6.Q, Time1); R_TRIG_10(TON_6.Q); AWT_6(R_TRIG_10.Q, TxtMessage, TxtMessageData[EvtMsg]);

END_FOR;

SendDone := TRUE; (* Function Block Done Bit *)


END_IF;