NI USB-6008 Differential and RSE connection

[evdo]

Hi everybody,

I have an NI USB-6008 and I have two simple questions. The wiring connection for this module is either Differential which gives you 4 channels or RSE which gives you 8. Does anyone know if you can configure the channels to have both connections? For example 2 differential channels and the rest RSE?

Also, in the user guide they give the input ranges for each mode and for example for the RSE it gives +/-10 V. Does this mean it has to be exactly this or it can be 0 to 10V or maybe 0 to -10V???

Thanks for the help...

[Caseyw]

I don't believe that it is possible to use both differential and RSE connections within one input task. For the input ranges, you can specify any range that is a subset of the -10V to 10V range. In fact, specifying your range as exactly as possible will help improve the resolution of your measurement.

I hope this helps.

Casey Weltzin, National Instruments

[Neil_S.]

evdo,
I was able to set up  a task using a USB-6008 using both Differential and RSE terminal configurations(see attached). Obviously, each differential channel will reserve two pins that cannot be used in RSE configuration.  However, it should be possible to create a task with the channel configuration you mentioned.

Regards,

Neil S.
Application Engineer
National Instruments

[Will.D]

Neil is right.  You can have both going in a task.

With regards to your other question, ±10 is available as, like Casey said, any subset of of that range, no greater than 10V.  This applies for RSE inputs, but for differential...

An excerpt: "The differential input mode can measure ±20 V signals in the ±20 V range.  However, the maximum voltage on any one pin is ±10 V with respect to GND. For example, if AI 1 is +10 V and AI 5 is –10 V, then the measurement returned from the device is +20 V."

[evdo]

Everybody thanks for the help 🙂

Dear Neil, I have a question for you. I see in your example that you are using the DAQmx subroutines instead of the DAQ assistant. Is there a reason for this? Because I find the DAQ assistant so much easier to use and ever since they switched these USB modules from the DAQmxBase to DAQmx I only use this. Am I missing something?

Thanks again,

Evdo.

[Neil_S.]

evdo,
You will be able to do the same with the DAQ assistant.  It is just hard to show what is happening in a single screenshot since each channel would be configured on a different screen.  I also tend to use the regular DAQmx VIs in my own programming since they provide additional flexibility.  However, in many applications the DAQ assistant is more than sufficient.  When using the DAQ assistant you can select each channel in the panel on the left side of the configuration window and set the terminal configuration on the Settings tab.  Hope this helps.

Regards,

Neil S.
Applications Engineer
National Instruments

[VeeJay]

I probably already know this but I would like a refresher.

I have an analog Differential and 2 analog RSE inputs. How do I acquire data from each channel simultaneously at regular intervals? Thanks!

V

[JÞB]

Well after 5 years this post can go again!

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@VeeJay wrote:

I probably already know this but I would like a refresher.

I have an analog Differential and 2 analog RSE inputs. How do I acquire data from each channel simultaneously at regular intervals? Thanks!

V

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You would create a task with 3 channels.  Use the DAQ assistant to create and save the task for easy access to the terminal configuration property or you can set the terminal config, Scale, and Range on each channel with a channel property node.  Use a timing node (or the vi) to set the sampling rate and start condiotions (triggered, on demand, Continuous  etc..)  and use Read.vi (whatever instance) to get your values.