self starting timer

hi folks,

I'm new to SCL and having the following question : why isn't this working ?
The idea was to have a 1 cycle pulse each 100 msec ( StartTimer1 inverted)

IF NOT "StartTimer1" THEN "StartTimer1" := true;
END_IF;

"CurrTime" := S_PULSE (T_NO:=1, S:="StartTimer1", TV:=100ms, R:=False, BI=>"TimeRemainTimer1", Q=>"Timer1");

IF NOT "Timer1" AND "StartTimer1" THEN "StartTimer1" := false;
END_IF;


The timer runs once but doesn't restart again !! StartTimer1 has a 0 to 1 transition !?!
Kind Regards

Johan