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Synchronization in FPGA with AO and DO


mhsjx

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Hi,

I'm a beginner in labview, and now test cRIO about two weeks. I still can not solve the problem. I attach my test project for explanation.

I want to realize that , for example, with time sequence t1, t2, t3, t4,  DO outputs T, F, T, F, AO1 outputs A1, A2, A3, A4, AO2 outputs B1, B2, B3, B4, and the delay of AO1 and AO2 should as small as possible(AO1 and AO2 may comes from difference modules).

I search in Google, NI forum, and decide to use for loop and loop timer in FPGA.

The reason as follow:

1. To realize the specific time interval, I can use Wait and Loop timer. But in "FPGA 0--Test DO.vi", it can't not realize specific time interval by several us's error(maybe large). And to complete once of while loop, it needs 134us. I can't explain that it can realize time interval below 134us, even I acturally realize a delay of 10us, but the input is not acturally 10us, so it's not accurate. 

And by NI example, I use the Loop timer.

2. In "FPGA 1--Test DO and AO.vi", I find that the loop timer helps me to realize accurate time interval, however, it ignore the first time interval. Such as, t1, t2, t3, t4, with disired output A1, A2, A3, A4. It goes A1(t2), A2(t3), A3(t4), A4(t1). And in "FPGA 2--Test DO and AO.vi", it has same problem. DO0 and AO1 goes A1(t2), A2(t3), A3(t4), A4(t1). And AO0 is always ahead of DO of t1. 

 

The people of NI forum advice that I should put AO0 and AO1 into one FPGA/IO node and use SCTL. But up to now, I don't find any example about it(Google or NI forum, maybe it's primary).  Mainly that AO0 and AO1 must go with different timeline, the dimension of input array is different.  Can anyone offer advice for me?

Thanks

Test.7z

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