Limited OI Range From Linear Slide Potentiometers

[Chaychay]

We are having a slight problem with our linear slide potentiometers.

They are 50K ohms and have about ~8 cm of linear motion. When connected to a multimeter monitoring resistance, we see the range of resistance go from approximately 0 to just over 50K ohms. However, when connected to the Port 2 of the OI, viewing the value on the dashboard gives us a range from 255 to 0 for only 6 cm of the sliding range; the remaining 2 cm show a value on the dashboard as 0.

The wiring is currently: Negative on pot to pin 4 on OI (ground). Positive on pot to pin 1 on OI (+5 V), & signal from pot to the appropriate analog signal pin (sorry, I forget which pin exactly)

Any ideas why we are loosing 25% (2cm/8cm) of our motion? The multimeter picks up the full range, so why cant the OI?

Any help will be much appreciated. Thanks!

NOTE: We have a spare pot which we will try this evening, but what confuses me is that nothing is wrong with this pot seeing as the multimeter detects a full range of resistance change, so I don’t think trying another one will work….but we’ll give it a shot anyway.