Hi All,
We use a couple (6) USB-6008 devices in our production facility where they are used to measure three signals. Two of them come from an analog distance sensor (Wenglor CP35MHT80) and the other comes from a potentiometer.
Everything normally runs fine for weeks, but then all of a sudden, some of the values (usually only one at a time) start to fluctuate somewhat. Although the potentiometer was kept in a steady position, one could see the values slowly change over time. This would create an offset that could result in several volts of error...
In the past, when they called me, I opened the box where the USB-6008 was in and tried to measure all voltages with a DMM and could not find a problem. And every time I did this, the problem disappeared.
Lately I close the software application first and start a test panel with NI MAX. I could then see the mis read. But when I then open the box and touch the USB-6008, the problem disappears! Yesterday I ran in the same situation. I could see the mis read in NIMAX. When I very gently pushed the black connector I could see the signal change. When I pushed it a bit harder the error was gone! It worked fine the rest of the day.
I have this problem on several (if not all) setups. It happens with all inputs. Yes, I have checked all screws and wiring for connection. All second analog inputs are connected to ground, to avoid floating inputs. Digital I/O are unused. On one setup we even put a ground wire from the analog ground of the USB-6008 to the ground of the PC.
My question is mainly to find out if this is something that some of you may also have experienced. Might this be due to bad connectors, or could it be me having missed out on something...
