Rockwell-automation Logix5000 Controllers Structured Text Programming Bedienungsanleitung PDF herunterladen (Seite 24)

24 Publication 1756-PM007D-EN-P - November 2012

Chapter 1 Program Structured Text

Example 3: IF…THEN…ELSIF

The [:=] tells the controller to clear Sugar.Inlet whenever the controller:

• enters the Run mode.

• leaves the step of an SFC if you configure the SFC for Automatic reset.

(This applies only if you embed the assignment in the action of the step

or use the action to call a structured text routine via a JSR instruction.)

Example 4: IF…THEN…ELSIF…ELSE

If you want this Enter this structured text

If sugar low limit switch = low (on) and sugar high limit

switch = not high (on) then

IF Sugar.Low & Sugar.High THEN

inlet valve = open (on) Sugar.Inlet [:=] 1;

Until sugar high limit switch = high (off) ELSIF NOT(Sugar.High) THEN

Sugar.Inlet := 0;

END_IF;

If you want this Enter this structured text

If tank temperature > 100 IF tank.temp > 200 THEN

then pump = slow pump.fast :=1; pump.slow :=0; pump.off :=0;

If tank temperature > 200 ELSIF tank.temp > 100 THEN

then pump = fast pump.fast :=0; pump.slow :=1; pump.off :=0;

otherwise pump = off ELSE

pump.fast :=0; pump.slow :=0; pump.off :=1;

END_IF;

1 2 ... 19 20 21 22 23 24 25 26 27 28 29 ... 39 40

Keine Kommentare

Rockwell-automation Logix5000 Controllers Structured Text Programming Bedienungsanleitung Seite 24