A function block groups an algorithm and a set of private data. It has inputs and outputs. - Detects High and Low limits of a signal with hysteresis.
Inputs
H : REAL Value of the High limit
X : REAL Input signal
L : REAL Value of the Low limit
EPS : REAL Value
of the hysteresis
Outputs
QH : BOOL TRUE if the signal exceeds the High limit
Q : BOOL TRUE if the signal exceeds one of the limits (equals to QH OR QL)
QL : BOOL TRUE if the signal exceeds the Low limit
Remarks
In FFLD language, the input rung (EN) is used for enabling the block. The output rung is the QH output.
ST Language
(* MyAlarm is a declared instance of LIM_ALRM function block *)
MyAlarm (H, X, L, EPS);
QH := MyAlarm.QH;
Q := MyAlarm.Q;
QL := MyAlarm.QL;
FBD Language
FFLD Language
(* The block is not called if EN is FALSE *)
IL Language:
(* MyAlarm is a declared instance of LIM_ALRM function block *)
Op1: CAL MyAlarm (H, X, L, EPS)
FFLD MyAlarm.QH
ST QH
FFLD MyAlarm.Q
ST Q
FFLD MyAlarm.QL
ST QL
See also
