Data Logging from FPGA without Host Vi to CVI

[mdontaraju]

I want read data from FPGA card through CompactRIO.  I have build an FPGA VI to get the data.I want to access this data  through CVI by building  FPGA VI as dll directly without using host VI. Can I do so? Is it possible to store the data in the FPGA VI itself and get that data in CVI periodically. CVI program should interact directly with FPGA VI with out host VI. Is it possible to achieve this. If so How?

[JMota]

Hi,

This is a good question. Unfortunately, the answer is no, you can't build an FPGA VI as dll directly without using a Host VI. In order to interface with an FPGA VI, you must use a Host Interface VI (it is conceivable that there may be a different interface to FPGA VIs in the future, but for the time being the only one is the Host VI).

So what you can do is to create a DLL out of the Host VI (or an executable), and then interface it from CVI. If there are reasons why this approach won't work, bring it up and probably people can think on ideas to overcome the difficulties.

JMota
National Instruments

[mdontaraju]

Hello,

Thanks JMota for your response.

Can we get some information regarding how the Host Vi interacts with The FPGA vi? What mechanism is adapted in transferring the data?

[JMota]

Sure (although it is probably not the information you would like to hear).

The Host VI interacts with the FPGA VI through the RIO Driver, which gets installed with the NI-RIO distribution. When the FPGA gets compiled, registers for the controls, indicators and control signals get created, and the NI-RIO driver in combination with LV FPGA Host Support take care of handling all the communication to transfer data into and out of the FPGA through those registers. Unfortunately, the details of that communication are not accessible to customers.

All I can say is that we know about the use case for not using a Host VI to communicate with an FPGA VI, and that engineering is actively looking into making this possible, but there is no timeframe for this to happen yet.

Sorry for not bringing much more light to the discussion.

JMota
National Instruments