Stuctured Text And Input Sensor

[dschmiddr]

If an input sensor sees an object and the PLC will count it then how can I do this with Structured Text. Since there is no one shot with ST the program I cutrently have will increase the value for each scan while the input is true.

 

[Dirt]

if bool and not bool_old then
count := count + 1;
end_if;

bool_old := bool;

But you should be able to call a one-shot-function in ST as well? Might depend on what system you're on..

 

[cardosocea]

Dirt's implementation is the correct way of doing a one shot in structured text.

 

[CommissioningMan]

The usual functions are called R_TRIG for Rising Edge Trigger, and F_TRIG for Falling Edge Trigger.
Since AB (and I suspect you are using AB) names anything and everything differently, the functions are called OSRI and OSFI.

Edit: Dirt's example can also be used for falling edge with a "NOT bool AND bool_old" check instead.