Variable forcing now uses limited list and buffer instead of systematical instance tree traversal and in-tree "fvalue" to keep track of forced value for pointed variables (external, located). Pointer swapping is performed when forcing externals and located, with backup being restored when forcing is reset. Match Beremiz commit 93ad018fb602.
FUNCTION_BLOCK LAG1
VAR_INPUT
RUN : BOOL ; (* 1 = run, 0 = reset *)
XIN : REAL ; (* Input variable *)
TAU : TIME ; (* Filter time constant *)
CYCLE : TIME ; (* Sampling time interval *)
END_VAR
VAR_OUTPUT XOUT : REAL ; END_VAR (* Filtered output *)
VAR K : REAL ; (* Smoothing constant, 0.0<=K<1.0 *)
END_VAR
IF RUN THEN XOUT := XOUT + K * (XIN - XOUT) ;
ELSE XOUT := XIN ;
K := TIME_TO_REAL(CYCLE) / TIME_TO_REAL(CYCLE + TAU) ;
END_IF ;
END_FUNCTION_BLOCK