software trigger the PCI-5122

[ques1]

hi
I am going to program a board with PCI-6552 and in meantime in specific times capture just one sample of the anolog output of the board by PCI-5122.
1) Can I use the digital output of one channel of PCI-6552 as trigger for PCI-5122 (to activate the fetching of PCI-5122) e.g. by connecting the output of PCI-6552 to the external trigger input of PCI-5122.
2) Does it need to synchronize the two boards.
2) Is there any example for software triggering the PCI-5122, and how long it takes from triggering to sampling the data.
3) How I can capture just one sample in every triggering time and then wait for another trigger time.

[Jeremy R.]

I'll answer the questions in the order given.

1. That should work fine. Just be sure you are updating with standard TTL levels (0-5V).

2. You won't need to synchronize the boards to do this either. Simply set your trigger source to be the external pfi line and that will work.

3. By searching our example code library and ni.com, I was able to find this example quickly:
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3E89156A4E034080020E74861&p_node=175383&p_source=External
I'm sure there are others as well. The timing will be dependant on how fast the command can be sent to the board. It is system dependant and therefore will not have a spec associated with it.

4. If you look throught the examples, you will see that
a common parameter in Minimum Record Length. By setting this to 1 and making your sampling rate you should be able to accomplish this. Or you could always just acquire more put throw away everything accept for the first sample each iteration.

Hope this helps.

Best Regards,
Jeremy R.
NI - Applications Engineer

[ques1]

"Just be sure you are updating with standard TTL levels (0-5V)", Does it mean that the digital trigger is available just when the voltage level is set to 0-5 V and not for e.g. 0-1.8V.

[Jeremy R.]

ques1,

Very good point. The 6552 does have programable logic levels. All of our Instruments, however, take standard TTL signals (0-5V) for all external triggers.

[ques1]

what about edge trigger? Does it also need to be at a TTL (0-5V) level?

[Jeremy R.]

No, edge triggering is usually done with an analog signal, so you define the voltage level at which to trigger. In this case, you can set up your 6552 at whatever logic level you'd like and then set up your edge trigger accordingly.

Jeremy R.

[ques1]

1) after programming the two output of the NI-6552 (DIO0 and DIO1) with the same pattern and connecting the DIO0 to Ch0 of PCI-5122 and DIO1 to external trigger of PCI-5122 and assigning the external trigger as the edge trigger source, the the signal is different from when the Ch0 is assigned as the trigger source. why are they different, also it does not accept two triggers sequentially. (Pic 1)


2)I am using a loop for generating the data and a loop for aquisition, when I using two trigger in one cycle and select niscope repeat_time=4, the signal position for 8 aquisition should be the same but as you can see in figure 3 the first two pulse are correct but the other ones are different.