I have bought and programmed a LOGO OBA8 with the correct AM2 RTD for Pt100/1000

with a 2 wire sensor i can not seem to get the correct values for the temperature, do i need to add something in my program that corrects the differential and offset if you like.

so grab the detail and then pass it through a number of corrective steps to give me an output, i have tried messing around with the offset but this is not clear to me as yet as being the answer i can move it one way and it seems to not be very linear, i am sure i am doing soemthing wrong its just what.

Thanks

The unit does function when holding the temperature i can see the temperature moving and when i let go it cools down so the program functions its more that the error is massive, when running the unit through a dry well (a temperature calibratora) i get a huge deviationat 85 degrees c i am reading 40 degrees c i wondered if i have to do anything with the off set i i move the offset i can vary the result.

i tried to clip the program to this mail but it wont let me it want an image rather than the code

PB

i am under 4 m but as you mention it is 2 wire.. i would have expected error in the results but the error is massive.

Siemens dont suggest a Pt100 to use and there are a lot out there i can only assume i have the wrong one.

http://uk.rs-online.com/web/p/platinum-resistance-temperature-sensors/6117801/?searchTerm=611-7801&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B337D5B5C732D2F255C2E2C5D5C647B332C347D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3631312D3738303126

from RS this is the sensor