Hi Roger..

I have problem with Campbell 107 Temperature Probe (Betatherm 100k6A1B Thermistor). I try to connect with DT80 series 3 and do wiring YSI/Meas Thermistor (4-wire). However, they can't read the value.

Plz help me Roger...

Thanks

Warm Regards
JamilTajam

Hi Jamil,

Roger is no longer with dataTaker, he still visit this forum though. :-)

You can't use a normal YSI setting for reading Campbell 107, on page 10 sensor manual, you can see the wiring diagram of the sensor.
In dataTaker you should read Vx (excitation voltage) and Vs (output voltage).
Since two fixed resistances of the sensor are not equal (249 kohms and 1 kohms), you can't use bridge configuration.

You need to wire the sensor as follows:

• black wire to 1+ DT terminal
• red wire to 1- DT terminal
• purple wire to 1# DT terminal

Vx is between 1+ and 1# terminal which you may get it using 1+V
Vs is between 1- and 1# terminal which you may get it using 1-V

Then you can calculate Rs using Campbell formula: Rs = 1000 • (Vx/Vs) – 249000

To get temperature reading you need to use Steinhart-Hart formula:
T = 1 / (a+ (b x ln[Rs])+ (c x ln[Rs]^3)), T in Kelvin

You may find a, b and c from sensor documentation (Campbell?)
In dataTaker, you can define thermistor scaling to use Steinhart-Hart formula.

Best regards,
Rudy Gunawan

Dear Rudy..

Many thanks for that info.. i already did what you suggested.. however.. i still do not get the result..
the command as bellow;

T1=0.000828358,0.000208633,0.000000081"K"

RS1S

RA1S LOGONA GA
1+V("Vx",=1CV)
1-V("Vs",=2CV)
3CV(=4CV)=1000*(1CV/2CV)-249000
4CV(T1)
END

and the result are

Vx 0.685112 mV
Vs 0.513512 mV
3CV -247665.82
4CV 0 K

is it they need external power input or excitation? or my sensor already fault...

Plz give me some advice... many thanks Rudy... MGBY...

Regards
Jamiltajam

Hi Jamil,

At this moment dataTaker just read any floating voltage in the terminal because I forgot one important component.
The sensor need an external supply of 2.5 V between black (+) and purple (-) wire.

You should wire together that supply in terminal 1+ and 1#.

Best regards,
Rudy Gunawan

good day Rudy..

Forgive me for interfering you again.. actually, i still not get the actual value, because Rs value was -ve..

please check my command..

T1=0.000828358,0.000208633,0.000000081"K"

1SSPWR=1
'schedule definition
RA("B:",ALARMS:OV:100KB,DATA:OV:1MB)1S LOGONA GA
1V("Vx",=1CV)
1+V("Vs",=2CV)
3CV(=4CV)=1000(1CV/2CV)-249000
4CV(T1,=5CV)
6CV=5CV-273.15
END
'end of program file

then the output as below;

Vx 2545.8094 mV
Vs 1870.1562 mV
3CV -247638.7---------- Rs Value (used formula (1000*(Vx/Vs)-249000))
4CV 0 K
6CV -273.15 degC

Correct me if i'm wrong..
Thanks for your time... i appreciate that...

Regards
Jamiltajam

Hi Jamil,

Could you check the resistance value between black/red wire (according to UM it should show around 249 k) and between red / purple wire (according to UM it should show around 1 k)?

This is just a simple voltage divider, so the output voltage should not reach that level (if the resistance value is referring to UM).
Assuming there is no thermistor resistance just 249k and 1k ohms, using voltage divider formula we can make an approximation value.

Vs=(1 kohms/(1kohms+249kohms))*2500 mV=10mV

Best regards,
Rudy Gunawan