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### Topic: TEMPERATURE MEASUREMENT (Read 2377 times)previous topic - next topic

##### Jul 02, 2013, 09:24 pm
Hello everyone,
I am new in arduino programming, I am working on the project of measuring a temperature using rtd pt100 and then i have to monitor it on PC using GSM module by sending the text of current temperature and receiving it by using gsm module. I am wondering about the communication between rtd and arduino about coding, please some one help me..
thank you.

#### robtillaart

#1
##### Jul 02, 2013, 09:31 pm
If you are new to programming then GSM is quite a big project as your first project.

I would strongly advise to go through the tutorial pages of the website to get familiar with the do's and don'ts of the Arduino language. In a few days you will learn a lot and more important recognize pieces of code that look like the ones you need.

- http://arduino.cc/en/Tutorial/HomePage -

Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

#2
##### Jul 03, 2013, 05:21 pm
hello,
I am getting the voltage and resistance of rtd but still not geting the temp in degree C please any one tell me the conversion formula
thank you

#### robtillaart

#3
##### Jul 03, 2013, 07:41 pm
you should look at the datasheet of the RTD for the formula, do you have it?
Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

#### levon

#4
##### Jul 05, 2013, 03:02 pm

hello,
I am getting the voltage and resistance of rtd but still not geting the temp in degree C please any one tell me the conversion formula
thank you

This is what I got from the book that came with the starter kit (unfortunately the spine came off after only 2 days, but lots of good stuff in there):

float voltage = (sensorVal/1024.0) * 5.0;
Serial.print(", degrees C: ");
float temperature = (voltage - 0.5) * 100;
Serial.print(temperature);

#5
##### Jul 10, 2013, 03:39 pm
To get the temperature form rtd i only mad the voltage divider circuit with 1k resister and rtd and connected the voltage pin directly to arduino-analog pin without doing any signal conditioning and i also did the conversion from resistance to temperature in degree C and the reading are as below,
Vo (921)- Rt(109.45) T(C)- 24.28
Vo (922) -Rt(108.26) T(C)-21.21
i am getting exact conversion from resistance to temperature as we see from the Rtd table. Though the problem is after changing of one least significant bit from the voltage it changes the temperature of about 3.07 degree C. but i want more accurate reading can anyone tell me the solution please..
Thank you.

#### Nick_Pyner

#6
##### Jul 10, 2013, 04:15 pm

To get the temperature form rtd i only mad the voltage divider circuit with 1k resister and rtd and connected the voltage pin directly to arduino-analog pin without doing any signal conditioning .......want more accurate reading can anyone tell me the solution please..

Maybe this will help.

http://openenergymonitor.org/emon/node/75

A difference amplifier takes the output voltage of the input stage and converts it to a voltage that uses the full range of the arduino analog input maximizing accuracy.

#7
##### Jul 10, 2013, 04:22 pm
hello, i removed the mux part from this ckt and i made it for only one rtd but it gives me very wrong reading its horrible reading.. and also the library given in that link is unuseful it doesnt work..

#### Nick_Pyner

#8
##### Jul 11, 2013, 02:22 am

the library given in that link doesnt work..

I think you had better trawl Google and see if anybody else has reached the same conclusion. I understand that stuff is the common benchmark but I'm afraid I haven't actually used it myself as, while I am making up some PT100 gear, I prefer to use DS18B20s.

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