how to transfer a single data from RT to FPGA

[SaCi]

I am starting work with CRio 9012, I would like to know how to transfer data from FPGA to RT, I have found something about DMA FIFOS, however I notice that is only possible to transfer arrays, i dont know if i am doing something wrong. I have another question, is it possible use global varible to tranfers data between RT and FPGA?

Filipe 

[nathand]

You cannot use a global variable to transfer data between the RT system and an FPGA, since they both run completely independently of each other and do not share memory.

A DMA FIFO can transfer a single point of data or multiple points of data; they are most useful for streaming data from the FPGA to the RT system or vice versa.  If there is only a single item in the FIFO the output of FIFO Read will be a single-element array.  For your use case the best solution is a front panel control or indicator; see the FPGA examples provided with LabVIEW.

[SaCi]

If i try use a DMA fifo to transfer data between FPGA and RT, i need to choose TYPE:  DMA HOST-TO-TARGET ok? or TARGET-SCOPED must be chosen? In this case my host is the RT and the target is FPGA ok? 

[nathand · Accepted solution]

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280584 wrote:
If i try use a DMA fifo to transfer data between FPGA and RT, i need to choose TYPE:  DMA HOST-TO-TARGET ok? or TARGET-SCOPED must be chosen? In this case my host is the RT and the target is FPGA ok? 

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Yes, you'll need to use "Host to Target" or "Target to Host" (the FPGA is the Target, RT is the Host); which one depends on the direction you want to send the data.  Target-scoped is for FIFOs that are used only on the FPGA; they are useful for transferring data between concurrent loops in FPGA code.