Wet and Dry bulb to Relative Humidity equation.

[Felixs]

Is it possible to calculate RH from two temperature readings using U90Ladder or should skip the calculations and use a RH sensor with analog signal instead?

The equipment we currently use has controller that does that, takes the temperature readings from two PT100 RTD's and controls the machine based on temp and humidity.  For what I have been reading the math behind the conversion is quite complex. 

Thanks

[Joe Tauser]

I've actually calculated dewpoint from humidity and temperature, which is a similar calculation.

Floating point math is involved, and you need at least a Vision series PLC.  Even better would be a UniStream.

Your best bet with your hardware is to get a humidity sensor.

Joe T.

[Felixs]

I understand and after reading and doing research I got a 4-20 mA RH transmitter along with a PT100. 

 

Thanks for your insight