Triggering of a system of 8 analog input channels

[DillonRankin]

Hello,

I am a student at UNLV and I'm working on a system with 8 analog voltages between -5V and 5V. I am using the NI DAQmx blocks in Labview. I've attached the code here. We have a set of four sensors measuring analog pulses that we need to trigger independently to record the pulses at all four inputs simultaneously. Each sensor outputs a different peak voltages at the time of triggering. We are measuring pulses that occur every ~10s with the trigger set at 0.75V. Is there any way to do this with our current hardware? We are using the analog start trigger, but we can only set one of the sensors as a trigger. Is there a way to set multiple inputs as triggers? Could some additional hardware solve our problem?

Thanks for reading and any help is greatly appreciated.

Hardware used:

NI PXIe-1071

NI PXIe-8135

NI PXIe-6363

NI PXIe-7954R

NI BNC-2110

[DillonRankin]

The title should say four inputs. My mistake.

[cbutcher]

To answer the directly asked question, you might have some luck using the "Start > Analog Multi-Edge" triggering method.

This will allow you to trigger one task if any of the triggers configured (you can provide multiple, hence the name) is triggered.

You'll still acquire all 4 channels at the same time - not just the channel responsible for the trigger though.

To get only the triggered channel, you need 4 separate tasks. Depending on your hardware (I didn't check, but I'd say your chances aren't bad? From the 6363 specifications, Analog Triggers > Number of triggers 1. Not so good for this approach...) you should be able to do this. Then, each task has a simple Analog Trigger, and only one physical channel from which to acquire. You have 4 acquisition loops in parallel. Consider the use of multiple VIs running asynchronously and a Queue using a Producer/Consumer system to gather your data from any of the producers you spawn (one per channel).

Edit: both of these approaches seem to be unavailable to the 6363 as I read the specifications. Considering further...

How fast is your acquisition rate? How comfortable would you be regarding FPGA programming? Is continuously acquiring all channels then post-processing the data to identify regions of interest a possibility for your application?

[Kevin_Price]

What devices support Analog Multi-Edge triggering?  Sounds like a nice feature.  I was unfamiliar with it and did a quick experiment with a simulated X-series device, which doesn't support it.  So far, I've only seen support for a cDAQ 9775 referenced online.

To the OP: if you don't have hardware support for multi-edge triggering, you might be able to handle this with continuous acquisition and software post-processing to extract the data surrounding the trigger conditions.  As a starting point, you could look at "Basic Level Trigger Detection" in the Waveform Monitoring palette (under Waveform Measurements).

-Kevin P