I am having several problems with my USB-6259. First, it is not accurately reading my thermocouples. I have K-type thermocouples connected to it, grouped together and scanning one after the other. I set my range to -100 mV to 100 mV, as they dont go above 50 mV. The data is very noisy (the thermocouples are grounded), and one of them is reading 55 mV. When I use a multimeter to probe the screw terminals on the board, it shows a more accurate 19 mV. For some reason this voltage is not being read by my system. I have no idea what to do. I am using a USB 1.1 port, not a 2.0, so would this have any effect?
One thing I did to try to remedy this was to set up just those 3 thermocouples in a separate program (I have pumps, compressors, other 0-5V signals coming in along with the thermocouples in my first program). When I set the sampling rate to 250kHz, and the number of samples to 8000, it pretty much fixed everything and the numbers were great. Two things: 1. I thought that decreasing the sampling rate would help make it less noisy because of settling times, but this is not the case in practice, and 2. with my full program, I can't run it that fast, so that solution didn't help me.
Does anyone have any idea how to get my program to work and display all of my data correctly. I am going to be using the PID control toolkit for cooling, based on the temperature data I read from this unit, but that wont work if my temperatures aren't steady, or correct.
Thanks in advance!
