NI 9148 and PCI R series

[jyang72211]

I have been using a PCI-7833R.  It is a PCI card with FPGA that goes into my PC.  It requires a breakout box and interface circuit to access all the signals.  I would like to switch to another form factor that would allow me to eliminate the need for a breakout box and interface circuits.  

I was looking into cRIO, but I learned that it requires the real time module, which I don't need and don't want to pay for.  I asked around and learned about the NI 9148, which has a FPGA and allows for signal conditioning module, but it doesn't require the real time module.  This solution is exactly what I need.  However, I am a little worry about communication.  It has a ethernet port on it, and it is used for network connection.  Since it is not connected to the host pc directly, what kind of communication delay should I expect?  If I use a cross over cable to connect the chassis and the PC directly, would it make the communication more reliable?  

Can someone do a fair comparison between the PCI-7833R and the NI 9148?  Thanks!

[srm@viewpointusa.com]

i have used both and like both.

i have been pleasantly surprised by the 9148 and how seamless it is to use.  the ethernet communications has not hindered our applications that use the 9148.

it is still a limited size FPGA and the analog rates are not the same (typical) as the 7833 but it has met our needs very nicely.

[jyang72211]

You mentioned that the ethernet communication has not hindered your application that uss the 9148, did you use a cross over cable that connect the 9148 and PC directly?  You mentioned that the FPGA for the 9148 is more limited.  I looked at the FPGA comparison between the 9148 and the 7833.  It seems like the 9148 is superior in all ways except for having slightly fewer LUT.  What other resource inferiority have you seen on the 9148?  I do notice that the analog rate and IO channel counts are less for the 9148, but it doesn't matter to me as much.

NI Device

Xilinx FPGA

# of Slices

Ethernet NI-9148

Spartan-3, 2 Million Gate

20,480

PCI/PXI-7833R

Virtex-II, 3 Million Gate

14,336

Slice definition

FPGA Family

# of LUTs

# of Flip Flops

Virtex-II

2

2

Spartan-3

2

2

[REDS]

Hello jyang72211,

You don’t need to purchase the RT module for the cRIO nor the NI 9148. All the Real Time components the targets require are already included in the NI-RIO drivers.

Regarding the comparison between the FPGA specs of the 9148 and the R Series, I would like you to read the Differences Between Xilinx FPGA Families for a more complete comparison of the hardware with different FPGA’s. Notice how the NI 9148’s Spartan 3 2000 (2 M gates) has more CLB (LUT’s and FF’s), but fewer multipliers and Block RAM than the PCI/PXI 7833R. 

[srm@viewpointusa.com]

REDS,

are you saying that you don't need LabVIEW RT to develop on the cRIO platform? because that was part of the original question.

@REDS wrote:

Hello jyang72211,

You don’t need to purchase the RT module for the cRIO nor the NI 9148. All the Real Time components the targets require are already included in the NI-RIO drivers.

Regarding the comparison between the FPGA specs of the 9148 and the R Series, I would like you to read the Differences Between Xilinx FPGA Families for a more complete comparison of the hardware with different FPGA’s. Notice how the NI 9148’s Spartan 3 2000 (2 M gates) has more CLB (LUT’s and FF’s), but fewer multipliers and Block RAM than the PCI/PXI 7833R. 

---

[REDS]

Hello Stu,

You do need LabVIEW Real Time support to program the cRIO. However, that support is installed with the NI-RIO drivers. What you do not need is to purchase the LabVIEW Real Time module to program it. You would need it if you want to use the cRIO as an RT host. However, you can bypass the RT host and transfer data from the FPGA to the Windows host, with no RT programming involved.

[srm@viewpointusa.com]

interesting.  is there an example project showing this capability?  i just coded an example that allowed me to target the FPGA directly from a windows VI.  i can't test it right now but this is the capability REDS described.  I learned something new today.

[REDS]

Hello Stu,

It’s just a matter of using a PC (Windows) host, as opposed to an RT host. You would need to call the same Open FPGA Reference VI as you would on an RT host, but you won’t have access to the functions the RT Module palette gives you. This is an example that shows a Windows host with an FPGA target.

However, please take into account that for truly deterministic applications, we recommend you implement an RT target, which you can set priorities to loops and other functionalities in order to have the more reliable application. Also consider that the information still has to be processed by the RT controller so that it can pass through the network, all over to your PC. This is a longer, less deterministic path than transitioning from the FPGA to the RT controller, which are inside of the same chassis.

Regards,

[srm@viewpointusa.com]

we typically use the FPGA for deterministic requirement and the host, either windows or RT it not critical.

this is functionality that we can use and did not realize was directly possible.

thanks for the tip.

[jyang72211]

Hi REDS,

The example shows a windows host with an FPGA target, but it uses a PCI R series FPGA card, and not a cRIO.  The card is installed into a PC, and there is no real time target, so it makes sense that the RT module is not required for programming that device. 

However, I am wondering do I need the RT module to program a cRIO.  I was told by another NI app engineer that all cRIO requires the RT module for programing.  The only exceptions are the 9148 ethernet RIO Expansion Chassis, and its equivalence.  The app engineer didn't even mentione dthe 9148.  Was he wrong?