triggered and continuous analog input togeather?

[lisa]

Hi,
I have a program set up based off a shipped LV example involving digital triggering of the analog inputs. It looks at a pulse and reads in ten points from the rising edge continuously. It appears that we are missing some pulse triggers and only reading in 126 triggers/sec instead of 128. We double checked the pulse and the frequency is correct (128Hz) so it seems as if the LV program is missing some of the pulses. Therefore, I want to use another analog input channel on the same 6062E daq card to continuously read in the waveform and see which pulses are being skipped. Is this possible?

[JeremyB]

Lisa,

I don't believe the E-series architecture will allow triggered and continuous analog input operations to occur in parallel. It is possible to set up different gains/input ranges but I'm 95% sure that the functionality that you are after isn't there.

If you are looking to keep track of the number of pulse seen by your application you could consider the use of a counter to count the number of rising edges seen by the NI 6062E - basically daisy chain the pulse train to the trigger input and the GP_CTR Source pin of the counter you wish to use. There are a number of examples around that should help with this. Running the counter and analog input operations in parallel shouldn't be a big problem - it might be that you would want to set up a buffered event co
unt operation for the counter as this will allow you to track and monitor every single trigger event seen by the counter while your analog input operations continue in parallel.

The other aspect to consider is benchmarking your application with the Profiler. If the problem is that you consistently only see 126 triggers/second, perhaps your acquisition loop is not running fast enough to cope with the data. This can be especially true if any data processing or file storage is taking place inside the acquisition loop. The Profiler will allow you spot bottlenecks and get a better understanding as to the performance of your application.

I appreciate this is perhaps not a direct answer but hope that it gives some ideas as to how to track down the cause of the problems you are experiencing.

Jeremy

[stu22]

Hi, a couple of suggestions could be that u may need a pre-trigger or u may have one. But if u don't the data u are losing may be down to the labview program not responding quick enough. A pre-trigger solves this by taking points before the trigger is pressed, but the program has to be continously running. it may be an idea to look at the triggered data aquisition examples in LV and modify them to your own needs.

Stuart

[Filipe A.]

Hello;

I'm not sure if I understood your application. You mention trigger pulses, but it seems you have an external pulse train clocking the analog input task.

If that is the case, you can't have onr of the Analog Input channels being clocked by an external clock pulse train and another channel, of the same board, clocked by the internal timebase.

Regards
Filipe A.
Applications Engineer
National Instruments