how can I change the input range of a USB 6008 in differential mode

[Christian Mergl]

First of all this would fit better in the hardware forums.

- What software are you using, so where do you want to change this settings?

- Do you want to change the input range (+/- 10V) or the terminal configuration (RSE, NRSE, Diff), or both?

Christian

[jens ole pedersen]

In fact what happens is: Im using a 6008 with labview, to meassure a 0 - 5v signal. Most of the times, there is no problem, but sometimes the 6008 starts up in a mode where the input range is less than 5V, and the input amplifier is saturated. I would like to know how I control the 6008, so this problem never happens.

[Christian Mergl]

"...sometimes the 6008 starts up in a mode where the input range is less than 5V"

The device is just doing what you tell it should do!

You can change the min/max values as well as the terminal configuration at the "Create Task.vi"

If you are using the Express VI DAQmx Assistent you set this in the task configuration.

Christian

[jens ole pedersen]

I am using "DAQmx Create Virtual Channel " to set differential mode and "analog voltage input". I leave minimum and maximum value "open" using the default 5V value. Should'nt that be okay?

Ole

[aeastet]

That is ok for you to use the +/- 5 VDC for the singnal. It is not uncommon for these channels to float if you have nothing connected to the channel. If you want to start these channels and them not to float you will have to hook something to them or provide a load across the channels such as you would to do a shunt cal.

[Christian Mergl]

How do you determin that the device starts with another range then specified?

You could use the channel property node to read the actuall configuration btw.

Christian

[jens ole pedersen]

I use the USB 6008 to sample values fra a pressure transducer (0-5V output). The first thing I do is to calibrate the pressure transducer with a minimum (0mm Hg) and a maximum (300mm Hg) pressure. If the 6008 is in a more  sensitive mode than +/- 5V it will saturate at a lower pressure than normal.