Daq 6052e Help (ext Analog Trigger)

[istarnes]

We are finally getting around to using our new 6052e and I have a few questions.

We have two external analog signals coming into the 6052e. The first signal is the trigger.
According to the help docs i can put this into PFI/TRIG1 pin.
Where does the ground go? Any AIGND? The second signal is the actual data.
does this go to ACH0 and the ground to any AIGND?

Next comes the logic (C++ Api).
We would like to setup a circular buffer using the rising edge of the analog trigger (1.5v). I am a little confused on the proper way to setup an External Analog trigger. If you could point me at the correct examples or give me a list of methods I should use that would be helpful. I see examples using digital triggers and examples u
sing HW(I am guessing Internal) Analog Triggers but no external analog trigger. Also if you have some recommendations for the best way to set this up. We need to get the data continuously at: 24chs x 416pts x 21hz = 209,664samples/sec(16bit)


thanks,
Ian Starnes
Niitek, INC.

[kroth]

Ian,

The PFI lines are used as digital inputs or internal routing lines. From the sounds of things you would like an analog trigger to begin your acquisition. The method for using analog triggering with our E-Series DAQ boards is to connect you trigger signal to one of the analog input channels. This channel will then be used as your trigger line. (Note: if you also want to acquire and log the data from that channel it will have to be the first channel in your scan list)

There is an example that ships with NI-DAQ, DAQsingleBufAnalogTrig.c
This example will trigger from channel 1 at the voltage you specify in the Configure_HW_Analog_Trigger function. The way the board works is that it sets up the trigger level and will then route that signal to the start trigg
er (PFI0) You need not worry about these signals as they are all routed internally; but your trigger signal is externally connected to AI channel 1.

For you grounding questions, this will depend on how you have your boards input mode configured, RSE, NRSE or differential. For information on how to connect your grounds to not create ground loops depending on your source and input configuration, View table 4-4 in your E-Series user manual. If you are in differential mode, then the channels are paired 0:8, 1:9, 2:10 ...

Hope this helps.

Kevin R

[istarnes]

Thanks for the help, I have been looking at this example and I guess was just confused on the internally routing from Analog input 1 to PDIO, and am still sort of.. So the analog trigger should go on Analog Input 1 and the Analog data can go on any Analog Input including Analog Input 0. I am confused on why it would be this way and not the Trigger on 0 unless Analog Input 0 is channel 1. Ahh let the confusion begin!

So right now I am about to try using AICH 1 as the trigger and AICH 9 as the Data Channel. Using the DIFF configuration.

thanks again,
Ian

[kroth]

Ian,

Don't worry this can take some time to fully understand all your options. If you are only scanning one channel ie using DAQ calls the trigger line will be the same as the data line. (This is how the example is setup, they just picked Channel 1, but could be zero as well). If you want to scan one channel and trigger from another, and are NOT using diff mode, then you can wire your analog trigger directly to PFI0, which is the line used for triggering the acquisition. If you want to scan more then one channel (using the SCAN functions) the trigger signal will be the first channel in your scan list. So if you are using differential mode and Channel 1(pos wire -> AI1 and neg -> AI9). Then your other data line must be 2-7.

The simplest solution
would be to not use diff mode, wire the trigger to PFI0 and the data line to any other AI channel. Differential mode is preferable however and may be the only solution depending on your source. In this case use the SCAN functions and setup your scan list for 0,1. Your trigger will be connected to differential channel 0, and your data will be connected to Channel 1.

Hopefully this made things a little clearer. If not, well see if there are some other specific points I can clear up.

Kevin R

[istarnes]

I had to take a break from researching the use of these boards in our product but am now back on the task. I have figured out how to setup the wiring per your advice but now am confused by the API. My confusion still is with the triggering. Is there or is there not a means for auto rearming the trigger?