Using USB 6225 can single ended and differential inputs be scanned together using Ni-daq and VB6?

[deide]

I have a application using the USB 6225 board were I would like to set some inputs for single ended mode and some differential mode.  I need to do a continious scan of all the channels at a rate of 50msec's.  I would be using NI - DAQ and Visual Basic 6.  Can I mix the channel modes and get the values returned together?   

[John_P1]

Hi deide,

Do you mean that you are using DAQmx?  The M Series boards aren't programmable in Traditional NI-DAQ.

If you are referring to DAQmx, then yes this is possible.  After you create a single task, you can call DAQmxCreateAIVoltageChan two times--one to specify the channels to configure as RSE, and the other to specify the channels to configure as differential. You can also configure channels to have different input ranges in this manner.

Best Regards,

[deide]

Thanks

Yes I meant DAQ mx.  I would run out of channels if they all had to be differential. 

[SLamazon]

Hello

I have USB-6255 DAQ which required external SCB-68 for instrumentation.

I have 8 SCB-68 devices but at a time i can connect only 2 SCB-68 device to USB-6255.

In my application, i need to connect 40 differential analog input channels and 40 single ended analog input to effectively monitor 40 power rails of embedded system (at least 30 power rails)

I am using SCI-Lab script to gather data from the DAQ. So far i have hooked up 8 power rails (i.e.. 8 differential channel + 8 single ended channel) and that is working fine.

From SCB-68 quick reference label, it has 15 analog input channels. In my connection, each power rails it consume 3 channels (i.e.. 2 for differential + 1 for single ended), so i can effectively connect 5 power rails using 1 SCB-68.

All other channels are digital and PFI which are useless for my application.

So even i use 2 SCB-68, i can connect only 10 power rails. I need to hook up other 30 power rails (at least 20 more).

Datasheet of USB-6255 says it is 80 channels  DAQ. So, how should i set DAQ or SCB-68 for all analog input channel. i do not require to connect any digital input.

May i have your support please?

Your kind help will be really appreciated.

SL-Amazon

[SLamazon]

Hello

I have USB-6255 DAQ which required external SCB-68 for instrumentation.

I have 8 SCB-68 devices but at a time i can connect only 2 SCB-68 device to USB-6255.

In my application, i need to connect 40 differential analog input channels and 40 single ended analog input to effectively monitor 40 power rails of embedded system (at least 30 power rails)

I am using SCI-Lab script to gather data from the DAQ. So far i have hooked up 8 power rails (i.e.. 8 differential channel + 8 single ended channel) and that is working fine.

From SCB-68 quick reference label, it has 15 analog input channels. In my connection, each power rails it consume 3 channels (i.e.. 2 for differential + 1 for single ended), so i can effectively connect 5 power rails using 1 SCB-68.

All other channels are digital and PFI which are useless for my application.

So even i use 2 SCB-68, i can connect only 10 power rails. I need to hook up other 30 power rails (at least 20 more).

Datasheet of USB-6255 says it is 80 channels  DAQ. So, how should i set DAQ or SCB-68 for all analog input channel. i do not require to connect any digital input.

May i have your support please?

Your kind help will be really appreciated.

SL-Amazon

[Prickly_Pear]

Hello SL Amazon,

It sounds like you are working on an exciting project. I want to wish you luck on your work.

I would like to clarify with you whether you are using a USB-6255 or a PCI-6255. The USB version should have all of its screw terminals on board, but the PCI version does need two SCB-68 connector blocks like you had mentioned. I'll believe that you meant to say PCI-6255.

I would also like to clarify that you do not need to use 3 channels to measure one signal.The 6255 is capable of measuring 80 signals at at time using single ended configuration or 40 signals with differential configuration. In the singled ended configuration you wire your signal to one AI channel and the reference to AI ground. In differential configuration, you wire your signal to one AI channel and ground to another AI channel. The DAQ card reads both channels and subtracts one from the other. AI 8 is the negative terminal for AI 0. AI 9 is the negative for AI 1. AI 10 goes with AI 2 and so forth.

Also, I would like to show you that the first SCB-68 is actually capable of 16 AI channels (AI 0-15) and the second can use 64 AI channels (AI 16-79) when used with the PCI-6255 like you have. That will give you access to all 80 AI channels. Here are some links to the quick reference labels: the first SCB-68 connector block http://digital.ni.com/public.nsf/$CXIV/ATTACH-AEEE-8FMTL7/$FILE/SCB-68%20M%20Series%20conn%200.pdf the second SCB-68 connector block http://digital.ni.com/public.nsf/$CXIV/ATTACH-AEEE-8FMTK2/$FILE/SCB-68%206225%20&%206255%20conn%201....

Also, in the future I think that it would be best if you made a new thread for posts like this. This problem is similar to the one discussed previously in the thread, but ultimately it is a different problem and deserves to have its own thread.

Again, best wishes on your project.

Jeremy P.