FUNCTION_BLOCK fb1
VAR_INPUT
auto:bool;(*0:man,1:auto*)
pv:real;(*process variable*)
sp:real;(*set point*)
x0:real;(*manual output*)
kp:real;(*proportionality gain*)
ti:real;(*reaet time*)
td:real;(*derivative time*)
ts:time;(*sampling period*)
end_var
var_output
out:real;
end_var
var
x1:real;(*last err*)
err:real;(*sp-pv*)
outi:real;(*reset output*)
outd:real;(*derivative output*)
end_var

err:=sp-pv;
if(ti>10000 or not auto ) then
outi:=0;
elsif auto then
outi:=outi+err*DINT_TO_REAL(TIME_TO_DINT(ts));
end_if;
if not auto then
out:=x0;
else
outd:=(err-x1)/DINT_TO_REAL(TIME_TO_DINT(ts));
x1:=err;
out:=kp*(err+outi/ti+outd*td);
end_if;
end_function_block