Hi, I would like to ask you for some help.
I've been trying to run CNR4 sensor measuring temperature with the thermistor using the example program included in the CS instruction manual but I've not been succesfull. The temperatures always range between 200-300 celsius degrees (in an environment with 20 celsius degrees). So I used the example program to measure temperature with Pt-100 and in this case the temperatures measured were right.
Then, I don't know why the temperature measurements with the thermistor were wrong. do you know anything about this problem?
Regards
* Last updated by: Camilo on 9/3/2014 @ 5:51 PM *
Did you buy the sensor from Campbell Scientific. We fit a bridge resistor in the end of the cable to allow this measurement. Without the resistor you will get results similar to those you see.
Andrew,
thanks for answer,
I bought it to a CS agent in my country, but it hadn´t the bridge resistor in the end of the cable. What kind of bridge resistor does it need?
Regards
I suggest you complain to your CS agent as it would appear you have be supplied with the sensor directly supplied from Kipp which will be confusing to wire up - check all the wire colours are correct too.
This is no great secret though. The program needs a precision 1kohm resistor between the excitation output of the logger and the thermistor connection to an analogue input. The other wire from the thermistor is connected to the logger ground.