This chapter describes simulation signals, which can be used during development and testing of the programming code. The machine or the hardware panel is often not available, when the PLC code and program needs to be tested. The hardware has possibly not arrived onsite, the machine is not built yet, or the PLC equipment is already shipped to the customer. Therefore, it can be advantageous to be able to simulate ‘sensor’ signals to verify that the PLC program is working as expected.
Below are programming code examples for four simulation signals, where the frequency and amplitude can be adjusted to meet your requirements.
The signals can be combined to create new simulation signals like this:
MySignalWave:= TriangleWave + SineWave;
Sine wave
VAR SineWave: REAL; //Wave signal n: REAL; //Counter a: REAL:= 1; //Amplitude hz: REAL := 0.001; //Hz END_VAR n:= n + hz; SineWave:= SIN (n);
Triangle wave
VAR n: REAL; //Counter a: REAL:= 1; //Amplitude hz: REAL:= 0.001; //Hz TriangleWave: REAL; //Wave signal Length : REAL := 2; //Length on/off signal END_VAR n:= n + hz; TriangleWave:= a + n; IF n > Length THEN n:= 0; END_IF;
Square wave
VAR n: REAL; //Counter a: REAL:= 1; //Amplitude hz: REAL:= 0.001; //Hz SquareWave: REAL; //Wavesignal Length : REAL := 2; //Length on/off signal END_VAR n:= n + hz; SquareWave:= 0; IF n > Length/2 THEN //50% duty cycle SquareWave:= a; END_IF; IF n > Length THEN n:= 0; END_IF;
Square wave (filtered)
VAR n: REAL; //Counter a: REAL:= 1; //Amplitude hz: REAL:= 0.001; //Hz SquareWave: REAL; //Wave signal Length : REAL := 2; //Length on/off signal Filter : LP_Filter; //Filter Function block *) FSquareWave: REAL; //Wave signal filtered END_VAR n:= n + hz; SquareWave:= 0; IF n > Length/2 THEN //50% duty cycle SquareWave:= a; END_IF; IF n > Length THEN n:= 0; END_IF; //Filter signal Filter(ValueRaw:= SquareWave, k:= 0.01, ValueFiltered => FSquareWave);
