Use duplicate symtable instead of symtable for enum constant value table (this will later allow us to detect semantic errors in IEC 61131-3 source code)
FUNCTION_BLOCK TRANSFER
VAR_INPUT
AUTO : BOOL ; (* 1 - track X0, 0 - ramp or hold *)
XIN : REAL ; (* Typically from PID Function Block *)
FAST_RATE, SLOW_RATE : REAL ; (* Up/down ramp slopes *)
FAST_UP, SLOW_UP, (* Typically pushbuttons *)
FAST_DOWN, SLOW_DOWN : BOOL;
CYCLE : TIME ; (* Sampling period *)
END_VAR
VAR_OUTPUT XOUT : REAL ; END_VAR
VAR XFER_RAMP : INTEGRAL ;
RAMP_RATE : REAL ;
END_VAR
RAMP_RATE := 0.0 ;
IF NOT AUTO THEN
IF FAST_UP THEN RAMP_RATE := FAST_RATE; END_IF;
IF SLOW_UP THEN RAMP_RATE := RAMP_RATE + SLOW_RATE; END_IF;
IF FAST_DOWN THEN RAMP_RATE := RAMP_RATE - FAST_RATE; END_IF;
IF SLOW_DOWN THEN RAMP_RATE := RAMP_RATE - SLOW_RATE; END_IF;
END_IF ;
XFER_RAMP (RUN := 1, CYCLE := CYCLE, R1 := AUTO,
XIN := RAMP_RATE, X0 := XIN) ;
XOUT := XFER_RAMP.XOUT;
END_FUNCTION_BLOCK