Differences Between USB M-Series and USB X-Series

[josborne]

Here's a good question for some NI product engineers:

I have built a fairly complex USB-DAQ system using a NI USB-6351, which is an X-Series device.

However, I would really like to have BNC connectors on the device.  So I am considering switching to the NI USB-6259 BNC.  But I notice that it is an M-Series device.  There don't appear to be any X-Series USB devices with BNC connectors, unfortunately.  So I am wondering if my application will allow me to "downgrade" to the M-Series version.

According to this page, there are some key differences between X and M series.  But I am having trouble understanding them correctly.  My fear is that I buy the new device, only to find that my code is totally dependant on features that are only available in X-Series devices. 

Below, I will attempt to summarize the features of my application.  Can someone out there tell me if my code will will run on an M-Series?

• I have three simulataneous tasks:  one AI and two DO tasks. 
• I use one of the DO tasks as a simple start/stop trigger.  So I simply hardwire the output from P1.1 into PFI0 to starts/stop the other two tasks.
• To get the other two tasks to start at the same time, their start triggers reference the same PFI line.
• To stop at the same time, I use a "reference trigger" for the AI and a "pause trigger" for the DO.  These two both reference the same PFI line.
• My DO on P0.0 is a buffered 60kHz signal

My concern is that only X-Series allows:

1. Dedicated sample clocks for digital I/O tasks.
2. All tasks are retriggerable.

Does Point 1 means that I can't have two independantly running DO tasks (which my application requires)?

And does Point 2 mean that I can't use reference or pause triggers (which my application requires)?

I feel that it is a little vague what these really mean.

[Allison_M]

Hi josborne,

You will not be able have two independently running DO tasks using an M-series device. Only X-Series devices provide this functionality.

Regards,

[josborne]

Thanks, allison! A quick follow-up:

Instead of an X-Series USB DAQ board, could I switch to a USB CompactDAQ chassis with an AI module and a DO module? Would that be able to achieve my requirements above?

Btw: My AI task is doing 5kS/s on about 8 channels.

I have never used cDAQ, but I assume it should be pretty straight forward to port my code to use cDAQ since they both us NI-DAQmx.

[Allison_M]

Hi josborne,

Yes. You should have no problems implementing your system using a USB CompactDAQ chassis with the modules you discussed. For getting started guides and product information please see this website: https://www.ni.com/docs/en-US/. 

Regards,