Hello all,

I want to connect a pyranometer to a S7-1200 plc. The pyranometer signal is 0-120mV which stands for 0-1250W/m^-2 irrandiance. The main problem is on how the signal is scaled. Can anyone help me? 

Thanks a lot

10V = 27648, so

.125V = 345.6

so an input of 346 raw counts would equate to 1250 w/m2.  Not much resolution in this.

You may be better off going through a transducer or amplifier to change this from 0 - .125V to 0 - 10V.

Hi!

I know that there are two types of guys out there. One who makes stuff and one who buys it.

In the case of industrial projects I buy them. You can buy an amplifier like this, they are also called "analog signal converters".

Here is one from Phoenix Contact and one from Siemens.

Engineer_Athens

Thank you for helping me. I know that I will lose a lot due to resolution but I'm not quite familiar with electronic circuits so as to make an amplifier. Propably I should ask for a professional  to do that for me.

 Have you considered an analog input signal module or signal board for the S7-1200?

SB 1231 AI 1x12 bit (1 input)

SM 1231 AI 4 x 13 bit (4 inputs)

You can configure the range of voltage down to +/- 2.5 Volts. Not ideal for your case but might be worth looking into. The S7-1200 System Manual Appendix has information about these devices.

May help a little bit, but even at 2.5V, you are still 20:1 away from full scale.  Not ideal and most of the data will still be electrical noise.

Amplifier or different choice of output configuration is still the better choice.