RT parallel loops caused FPGA vi channel mixup?

[wrath_of_con]

I have two FPGA vi's that are mainly used as digital i/o. Each vi has addresses different pins on the FPGA card.

I was attempting to create a Real-Time vi that would have two parallel loops of different loop rates, with FPGA1.vi in one loop and FPGA2.vi in the other loop. FPGA1 loop controls motor1 for example, and FPGA2 loop controls motor2.

Here's the problem:
Upon running the Real-Time parallel loop vi, the control of the motors seemed to be crossed. What I mean is, FPGA1 now began controlling the second motor, when in fact it should be controlling the first based on the digital inputs. A toggle switch on the first actually controlled the second.

I was almost as if running two FPGA vi's within parallel loops o
n the Real-Time computer caused the signals to be crossed.

Any ideas on why this happened? Multiple FPGA vis should be able to be called from Real-Time loops right?

Thanks in advance,

- Con

[Christian_L]

A few basic questions:

Do you have two RIO cards and are you targetting the two FPGA VIs to the two different cards?

You can only run one FPGA VI on a RIO card (78xx) at a time. If you open a reference to a second VI on the same RIO card, it will replace the first VI that is running on the FPGA. If you only have one FPGA card you need to combine the contents from your two FPGA VIs into one VI to be downloaded to the RIO card.

Christian L

[wrath_of_con]

While we do have two RIO cards, my problem has to do with vi's on the same card. We are using the PXI 7831R FPGA card.

You can only run one FPGA VI on a RIO card at a time?!?

"If you open a reference to a second VI on the same RIO card, it will replace the first VI that is running on the FPGA. If you only have one FPGA card you need to combine the contents from your two FPGA VIs into one VI to be downloaded to the RIO card."

I missed that information in the user manual - would you happen to have a link to National Instruments information on this subject?

Many thanks for your assistance!

- Con

[Christian_L]

Admittedly I can not find this stated clearly in the manual anywhere, but I will submit a request to get this added to our technical writers for the next revision of the manual.

Christian L
NI Consulting Services