DAQ Suggestions for analog input and output for lab setup

[ashenoy]

Hello, 

Here's my setup: I have six pressure regulators that allow me to output pressure between 0-20 psig. These regulators have a control signal driven by analog voltage 0-10 V, and a monitor signal analog voltage 0-10 V. The monitor signal allows me to read out what pressure was actually output compared to the desired pressure. In my experiment, these pressure regulators are part of a feedback control loop, where the loop is driven at frequency of 30 Hz (I might be shifting to a higher frequency in a future ~100 Hz). Thus, the pressure needs to be updated every 33 ms (or lower in the future). I'm looking for NI hardware that can allow me to output and read 6 analog voltages at this loop frequency. The feedback voltage is calculated on a computer inside a labview program. The analog input will be used just for monitoring the actual pressure that was applied and will not be used for calculating the feedback pressure.

After browsing the website, I've shortlisted the following options:

1. NI USB 7845R + SCB-68A + SHC68-68-RMIO Cable 

2. NI PCIe-7841R + SCB-68A + SHC68-68-RMIO Cable 

3. NI cDAQ-9174 + NI 9201 + NI 9264

I was looking for feedback on these options regarding advantages and disadvantages, and other factors (for eg. USB vs PCIe) that I should consider. I'm also open to alternative configurations that serve the same process.

Thanks!

[AwakeTheField]

Hi Ashenoy,

It sounds like you have done a fair amount of research into this application, and I would be happy to try to give some input. Ultimately, though, I would recommend calling our Technical Sales Consultants line: (877) 387-0015. This would allow us to better assist you in choosing the best components for your application.

The main differences to keep in mind when choosing between your different options are:

• Bus speed requirements
• Ability to expand application
• Form factor

When considering the differences between USB and PCIe:

• PCIe has a faster data streaming speed
• USB devices are easier to transfer between computers and are more portable

When looking at our cDAQ chassis paired with C series modules, the things you can consider are:

• If you need to expand my application, you have multiple slots that I can purchase more C series modules in (VS. PCIe slots on your computer are often limited to 1 or 2)

You could also look at this White Paper article we have on choosing the right Bus for your measurement system: http://www.ni.com/white-paper/9401/en/ 

This is just a short example of things to take into account when making your decision here. Again, I would strongly suggest calling (877) 387-0015 to discuss your options with an NI Engineer.

I wish you the best of luck on this application!

[Kevin_Price]

I'd just add that since it appears you're looking to do real-time control, I'd recommend PCIe over USB and cDAQ (which is itself USB or ethernet based) due to *latency* considerations.

-Kevin P