synch e-series AI with Digitizer on first pulse of pulse train from E-serires Counter

[weizbox]

First off, I have a PXI-6025E DAQ card and a PXI-5102 High speed digitizer. What i need to do is to send out a pulse train from the DAQ for about 1 second, and at the same time, read a Analong In on the same DAQ card as well as the two Digitizer lines at the start of the first pulse in the pulse train, and then ending when the pulse train does (I can do the stop just based on the freq Im useing and use number of samples to time, os this isnt the problem). The problme for me is starting this event.

My setup is basicly 3 lines in , one AI DAQ and two for the digitizer. The TTL signal is going to a switch diode that one of the Inputs from the digitizer is coming from. Im useing the
pulse train to switch the source for my switch diode, and pulseing it at a high rate to compare the signals coming in through the switch diode. And as well I will be having to look at the other two Inputs at the same time.

How would I go about doing somthing like this?

PXI-6025E
PXI-5102
Labview 7.1
Windows XP

Thank you very much,

Mark Wiesbock

[Tiptop]

Hello,


So it looks like we can do this, the trick will be getting everything to start on the same digital trigger.

Let�s start with the DAQ side, with the pulse train generation. For this application we will need to use the new DAQmx drivers. The reason is that DAQmx supports digital triggers for pulse train generation and the old driver does not.

There is an example that we should look at using. It is the �Gen Dig Pulse Train-Finite-Dig Start.vi� example, which can be found in the NI Example Finder.

Next, we can look at a different example for digitally triggering our DAQ analog input. A good example would be �Acq&Graph Voltage-Int Clk-Dig Start.vi�

As for using the digitizer board, we should look at the Configured Measurement shipping ex
ample that comes with NI-Scope, from here we can select a digital trigger.

We should be able to start these three programs, apply a digital signal, and see that they were all synchronized.

One other note, if you need to generate a digital start trigger, you could wire in one of your digital I/O lines as the trigger and set it high with a software call.

I know this is a lot of new information, just let me know what questions you may have.

Best regards,

Justin T.
National Instruments

[weizbox]

Thank you very much! Im going to be working on getting that all set up today so I will let you know how it turns out.

-Mark

[weizbox]

I belive I have everyhting up and running properly, but, as always, I have another thing I need to watch, another DAQ AI channel, not just one, but two, simultaneously. Ill be working around with it trying to get it set up. Let me know if you have any pointers. Thanks again!

-Mark

[Tiptop]

Hey Mark,

Reading data from two channels should not be hard. All that we need to do is specify two channels as input inside of the �Acq&Graph Voltage-Int Clk-Dig Start.vi�, however, realize that this will not be �simultaneous�. There will be a delay between the two signals.

If you would like simultaneous samples, this would require one of our simultaneous sampling boards, or another E Series board. With a second E Series board, we could route our clock signal from one board to the other, but there will be some nano-second delays from one board to the other.

Since synchronization of the signals can be done many ways, just let us know how closely the two analog inputs have to be sampled together and we will see what can be done.


Best regards,

Justin T.

[weizbox]

Turns out once again, Ill only be needing one, luckily. Still struggling with getting everyhting up and running, pretty frustrating, one minute it works, the next im getting tons of errors. Im going to start from scratch again and see how well it goes. My main issue right now would be to try and get 20MS/s on BOTH digitizer channels for a second... altho the card says it can only hold about 16 million, I need 40 million. How would I go about doing this? (assuming I can get them all synced in the first place again). I was trying to dig around in the stream to disk VI example, but it didnt really help too much, I was wondering if theres some wya i can put it right into the Ram on my pxi system... altho im not sure if i Have enough
for that, i have 512MB, and its maxed out. Anyway, let me know if you know of a good work around for this problem, Ill keep working on this thing to try to get it synched up again, not quite sure what went wrong.

Thanks again,
-Mark

[drkovrlord]

Mark,

Try using this modified example. In the "True" case in the while loop, you will need to change the trigger to "Digital" instead of "Edge". What this VI does is trigger on an edge [which you will replace with digital] the first time (assumedly your start trigger), then does immediate triggering after. If you want to trigger each time you get a pulse, then remove the case statement and replace it with just a digital trigger configuration instead. Good luck, man!

<-*DrkOvrlord*->

[weizbox]

thank you! definetly helped as well.

-mark