I have some T/RH sensors (Precon HS-2000V) and want to connect them to the DT 85. But I don't know how to connect the four wires.

Hi Will,

That sensor share common input and output, therefore shared configuration is the best choice:

pin 1 - temperature out - DT terminal 1* (analog)
pin 2 - voltage in - positive terminal of your power supply
pin 3 - RH out - DT terminal 1+ (analog)
pin 4 - common - negative terminal of your power supply and DT terminal 1# (analog)

Because this sensor uses voltage in value to represent maximum range, you MUST have a fix supply (i.e.: 5V) so you can easily apply the scaling.
Temperature reading range is -30...100 degC and RH range is 0...100%

So the program would be:

BEGIN
S1=-30,100,0,5000 'temperature scaling
S2=0,100,0,5000 'RH scaling
RA1M LOGONA
1V(A,S1,"Temperature~degC") 'reading voltage on terminal 1 between and #
1+V(A,S2,"RH~%") 'reading voltage on terminal 1 between + and #
END

Best regards,
Rudy Gunawan