How do I set-up and control the VXI TTL ch1 in LV6.1?

[jcrooke]

I have a VXIpc-870 with 6 DAC devices. I want the devices to output data synchronously. To do this I intend to use the VXI bus line TTL ch1 to clock the sequenced outputs, but I don't know how to configure a signal for this line, nor how to initiate the clock. Can someone point me to the correct LV vis for this and the sequence of calling them?

[JedRetherford]

jcrooke,

After reading your post I don't think there is quite enough information to point you to the correct way of programming your application. Could you please post some additional information on where your sync signal will be generated (internally/externally), what device you want to source the sync signal, and any other related information that might help these forums to better assist you with your application.

In addition to posting more information, you may want to take a look at the following tutorial, which discusses NI-VXI triggering in great depth:

Triggering with NI-VXI

That tutorial may be enough to get your application headed in the right direction. If not, please post some additional information.

Best of luck with your application.

Regards,
Jed R.
Applications Engineer
National Instruments

[jcrooke]

I looked up the VXI-triggering info. It looks like I can use the trigger functions to put a TTL clock signal on one of the VXI trigger bus lines. I am trying this, but when I probe the trigger bus lines with a scope, I don't see the signal.

As a simple test, I have tried the attached code to generate a pulse on the TTL0 line, which should be present on VXI plug 2, rowA, pin23.

Why doesn't this work?

[jcrooke]

The CLK10 signal doesn't show up on my back plane. When I probe plug 2, row C, pins 1 & 2, I get nothing but noise. Since the trigger functions use the CLK10 signal, it would seem that I need to verify that my TIC chip is putting the CLK10 signal on the bus. How do I get that signal onto the backplane?

[JedRetherford]

jcrooke,

I'm a little surprised that you are not seeing the CLK10 signal show up on the backplane, as I would have expected it to be there. You are checking the right pin numbers, but please make sure that you are checking the correct pins (and not the mirror image pins, etc.). Also, please keep in mind that this is a very fast signal, and adjust your scope appropriately.

If you don't see a CLK10 signal after completing the above steps, you may have something going wrong with your hardware. Do you have any other hardware that you could swap to double check the behavior? If you do, you may want to go that route. Otherwise, please post as much detail as you can about what you are doing and what you have tried/tested so far. That information may help this forum to more effectively help answer your questions.

Regards,
Jed R.
Applications Engineer
National Instruments

[jcrooke]

I used the MapTrigToTrig function to put the ext trig in on my VXI controller onto TTL0. I am using a function generator to generate the clock signal, but I would really like to use the VXI embedded controller to generate the signal using the TIC chip and put the signal directly on the TTL bus. Does anyone know how to do this?

[Shawn B.]

Have you tried using the TrigTickConfig and SrcTrig functions? This is explained under Example 10 that Jed posted above. This should work, unless your CLK10 signal is really not working. Give it a try, and if it does not work, we will have to figure out why your CLK10 signal does not work.

Shawn B.
National Instruments