Add check bison version in configure.ac file.
To build correctly matiec we need bison greater or equals than 2.4 version.
Now the "configure" script is able to check if system has correctly requirements.
FUNCTION_BLOCK AVERAGE
VAR_INPUT
RUN : BOOL ; (* 1 = run, 0 = reset *)
XIN : REAL ; (* Input variable *)
N : INT ; (* 0 <= N < 128 or manufacturer- *)
END_VAR (* specified maximum value *)
VAR_OUTPUT XOUT : REAL ; END_VAR (* Averaged output *)
VAR SUM : REAL := 0.0; (* Running sum *)
FIFO : DELAY ; (* N-Element FIFO *)
END_VAR
SUM := SUM - FIFO.XOUT ;
FIFO (RUN := RUN , XIN := XIN, N := N) ;
SUM := SUM + FIFO.XOUT ;
IF RUN THEN XOUT := SUM/N ;
ELSE SUM := N*XIN ; XOUT := XIN ;
END_IF ;
END_FUNCTION_BLOCK