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FunctionClosedA function calculates a result according to the current value of its inputs. A function has no internal data and is not linked to declared instances. Block - Up/down counter.

Inputs

CU : BOOL     Enable counting. Counter is increased on each call when CU is TRUE
CD : BOOL     Enable counting. Counter is decreased on each call when CD is TRUE
RESET : BOOL  Reset command. Counter is reset to 0 called with RESET to TRUE
LOAD : BOOL   Re-load command. Counter is set to PV when called with LOAD to TRUE
PV : DINT     Programmed maximum value

Outputs

QU : BOOL     TRUE when counter is full, i.e. when CV = PV
QD : BOOL     TRUE when counter is empty, i.e. when CV = 0
CV : DINT     Current value of the counter

Remarks

ST Language

(* MyCounter is a declared instance of CTUD function block *)
MyCounter (CU, CD, RESET, LOAD, PV);
QU := MyCounter.QU;
QD := MyCounter.QD;
CV := MyCounter.CV;

FBD Language

CtudFbd.gif (1604 octets)

FFLD Language

CtudLd.gif (1724 octets)

IL Language:

(* MyCounter is a declared instance of CTUD function block *)
Op1: CAL    MyCounter (CU, CD, RESET, LOAD, PV)
FFLD     MyCounter.QU
ST     QU
FFLD     MyCounter.QD
ST     QD
FFLD     MyCounter.CV
ST     CV

See also

CTU   CTD