NI 5752 Limited Digital Output pins

[Albert Chen]

Hi,

I am currently using a NI 5752 digitizer with NI PXI 7954R FlexRIO FPGA.

The specs for the digitizer is great but I'm limited to only 16 digital outputs.

For my ultrasound imaging project, I need at least 32 DOs. 

I called the support and found out that even though the  FlexRIO card boasts >100 DIO line the analog input uses multiple DIO lines on the FlexRIO, and therefore, the >100 lines in the specs are not only used by the DIO but by the ADCs as well.  As a result, it was not possible to reconfigure the IP to allow access of more DIO lines. 

So I still need at least 16 ADC at 50Ms/s with at leaset 32DOs...Internal clock for the FPGA must be >100MHz.

Does anyone have any suggestions? 

Thanks,

Albert Chen

[Peñata]

Hi Albert,

Unfortunately, at this time we do not offer an individual FlexRIO adapter module that meets your requirements (16 AI, 32 DO). As the support engineer that you spoke with pointed out, the I/O lines on the FPGA do not directly map to the I/O lines available on the adapter module. While the FlexRIO base card does expose a specific number of GPIO lines from the FPGA to the adapter module - 132 in the case of the PXI-7954R - these lines are often used for much more that user accessible DIO. For example, with the NI-5752, 92 of these lines are used to interface with the ADCs, 34 are used for the DIO, and the remaining 6 lines are used for other various communication between the FlexRIO and the adapter module.

However, perhaps we can find a workaround for your situation. Can you give me more information about what you are working on? What is your application doing? Would it be possible to use two NI-5752 adapter modules in your application? Or would it be possible for you to use one FlexRIO/adapter module combo for AI and a separate FlexRIO/adapter module combo for DO? 

Thanks!

Aaron P

National Instruments

Applications Engineer

http://www.ni.com/support

[Albert Chen]

Hi Aaron, 

Thanks for the reply.

I'm building an ultrasound imaging system using phased-array approach.

I need16 DO to control 16 ultrasound transducer pulses and another 16 DO to switch these transducers from transmitting to receiving mode.

Once in receiving mode, I need to listen to each of these transducers (i.e. 16ADC). I would also preferably like to use 32 channels instead.

I basically need to construct an almost identical system as this video to test out the Ultrasound Transducers that our lab created.

http://www.youtube.com/watch?v=_TjMOEcqBY4

The method they need would most likely require more than 16 DO...

If you can prove me wrong, I will be very happy. 😃

-Albert

[JohnnyH]

Hey Albert,

I was actually the one who filmed the demo video you saw, and I work with a number of customers on phased array research applications, so I can probably shed a little light on things.

As you mentioned, there are definitely times when an ultrasound imaging application might need more DO (and also AI) lines. For the 5752, our goal was to get 32 AI channels in a single slot, and then we added as many DO lines as we could given the number of lines available with the FlexRIO FPGA interface. So, for customers needing higher channel counts on the output side, we have two options:

1. I have worked with some customers who want to design the entire pulser circuitry and just have a digital interface. So for this case, you can maximize the number of DO channels with another digital-only FlexRIO module, or an HSDIO module (I have people use several different options). This is the best way to maximize the number of digital lines.

2. Diagnostic Sonar is actually in the process of porting their 32-ch pulser (the large box on the right) into a FlexRIO adapter module. While they will sell a "phased array system" that builds on what you saw with the demo video, they are also planning on making the pulser module available for sale individually to researchers or other companies who want to use it in their own custom system and have the ability to integrate it. They will also have hardware for additional amplification on the receive side if additional dynamic range is needed, and a customizable multiplexer board that can also provide a clean way to scale to higher numbers of channels (configurable in multiples of 32 on either transmit or receive) and array interfacing.

Please let me know if you're interested in finding out more about the hardware specs from Diagnostic Sonar and I'm happy to put you in contact with them. If you respond affirmatively to this message, I can get your email from Aaron.

I hope this helps!

John