PLC Programming

Appendix D: CoDeSys Libraries
IN of the type INT is fed with the value to be manipulated. The BYTE N designates the number of
points which defines the presentation function. This characteristic line is then generated in an ARRAY
P[0..10] with P of the type POINT which is a structure based on two INT values (X and Y).
The output consists of OUT of the type INT, the manipulated value and BYTE ERR, which will indicate
an error if necessary.
The points P[0]..P[N-1] in the ARRAY must be sorted according to their X values, otherwise ERR
receives the value 1. If the input IN is not between P[0].X and P[N-1].X, ERR=2 and OUT contains the
corresponding limiting value P[0]. Y or P[N-1].Y.
If N lies outside of the allowed values which are between 2 and 11, then ERR=4.
Example in ST:
First of all ARRAY P must be defined in the header:
VAR
...
CHARACTERISTIC_LINE:CHARCURVE;
KL:ARRAY[0..10] OF POINT:=(X:=0,Y:=0),(X:=250,Y:=50),
(X:=500,Y:=150),(X:=750,Y:=400),7((X:=1000,Y:=1000));
COUNTER:INT;
...
END_VAR
Then we supply CHARCURVE with for example a constantly increasing value:
COUNTER:=COUNTER+10;
CHARACTERISTIC_LINE(IN:=COUNTER,N:=5,P:=KL);
The subsequent tracing illustrates the effect:
RAMP_INT
RAMP_INT serves to limit the ascendance or descendance of the function being fed:
The input consists on the one hand out of three INT values: IN, the function input, and ASCEND and
DESCEND, the maximum increase or decrease for a given time interval, which is defined by
TIMEBASE of the type TIME. Setting RESET to TRUE causes RAMP_INT to be initialised anew.
The output OUT of the type INT contains the ascend and descend limited function value.
When TIMEBASE is set to t#0s, ASCEND and DESCEND are not related to the time interval, but
remain the same.
Beispiel in CFC:
CoDeSys V2.3 10-57