USB-6009 AI off by 0.4V

[Odje]

Hi all,

I recently purchased the USB-6009 Daq. I am having a problem with the analogue inputs. All the readings are off by 0.4V. I have verified this with a calibrated Fluke multimeter. I even connected the 2.5V output to the analogue inputs and it was read as 2.1V. A 9.99V input is read as 10.3V. I assume 10.3V is the limit of the device. I am using DaqMax test panels and Labview to view the readings. This problem appears to be intermittent. Some days it will work perfectly, other days it will refuse to give the correct reading.

Any help would be greatly appreciated.

[jaced]

Hi,

I would take a look at the Field Wiring and Noise Considerations for Analog Signals. It is important to understand the different methods of connections and considerations that must be taken for each. If you could post back with the exact configuration of your measurement then we can better understand the system and determine if this is a signal connection error or something that is wrong with the device/computer/cable. I hope this information is useful.

[Odje]

JaceD,

Thank you for the very informative article. All the AI are connected to ground referenced single ended.

I think I have solved the problem. One of the AI inputs was out of range (-10 to 10V) at about 14-15V. This was some how affecting the other AI inputs into giving incorrect readings where they were offset by 0.4V

Cheers
Odje.