s7-1200 sine wave

Hi
does any one have or know where I can obtain a function to generate a slow sine wave output of 4-20 ma with variable frequency and amplitude?
or any pointers on how to do it
this will be using a s7-1200 PLc
Regards
Mel

The 1200 has a SIN function. It should be easy enough to use the system time to turn that into a signal generator.

f = frequency
A = amplitude
t = time
p = phase offset
o = amplitude offset or bias

The general formula would be as below, although the constants change a bit depending whether you want radians or degrees.

signal = A * sin(f*t+p) + o

You'll need to do some data type conversions, but in the end you should be able to use the scaling blocks to pass the signal to your output card.

edit: for the smoothest/most regular curve, you can run this out of a cyclic OB instead of the main OB, but it should work fine either way.

thanks for your quick responses I have now got it working
regards
Mel