This erroe occours when i try to run program:
Error on line 1 is marked by a '#' character: " t_c=R*C; VR=Vo *# exp(-t/(t_c)); Vc=Vo*"
Vo is an array, you must index it and use a For Loop either inside or outside the Formula Node. I suggest outside, and while you're at it just use the Numeric functions instead of the Formula Node. You'll be happier in the long run.
I used numeric functions, but nyquist plot doesn't display anything. Is it working only with filters or something?
It's error: -20304 At least one of the time signal waveforms does not contain the correct dt to continue the averaging process.
The problem is that you convert the waveform for Y to a plain 1D array (thinck orange wire), thus losing all timing information. When it gets coerced back to a waveform at the subVI (note the red dot!), it substitutes the default dt=1. However, the X waveform has a dt=10m.
Since the two inputs now differ in dt, the function will fail.
One simple fix would be to delete the "convert from dynamic data" node and just reconnect the wire stubs. See how far you get. 😉