USB 6003: how to drive the trigger and how to trigger AO, and AI after a delay.

[r.flores]

Hello,

I am quite new to the DAQ, so my question might sound very basic but I could not figure out the answer by myself. My main problem is related with how the trigger works because I could not understand the concept.

I have a DAQ USB 6003 and I will use Matlab ToolBox to control it. For my experimental system I need to use 2 analog ouputs and 1 analog input, and I want to trigger the output voltage to a constant DC value at given time intervals, wait a specific time while holding the output voltages and read the analog input. 

My questions are:

1.  If I select PFI0 as a source trigger and I want to start it at the rising edge of a pulse signal generated by one of the channels of my DAQ, is this considered Hardware or Software trigger type?

2. Which channel type should be used to create the pulse signal and drive the trigger? Analog or Digital? Is there any channel specifically designed to generate this type of waveform (at a given frequency and duty cycle)?

3. Can I use the same channel simultaneously, for instance PFI0, to trigger on a rising edge the analog outputs and on a a falling edge the analog input? Or should I have two different trigger sources? Or even a third scenario, where I just use a wait function after the rising edge trigger?

Thank you for any help you can give me.

[Dennis_Knutson]

The PFI lines are used for hardware triggering. The trigger source needs to be TTL compatible and with your device, you only have the digital outputs as a trigger source. The digital lines are only software timed so you can't set one for a specific frequency or duty cycle.

[r.flores]

What does it mean to te TTL compatible?

Can the PFI0 source be an analog signal?

[JBarrman]

It means that have to respect the standard of the TTL technology, this means that it will interpret a range from ~0-1 V as a low state or logical zero and from ~3-5 V as a high state or a logical one, the zone that is in between this to ranges is called indeterminate. In this zone there is no way to predict how the hardware will interpret the source as a low or high.

Yes, the PFI0 could be an analog signal but when the signal surpass the threshold of 1 V there is no way to determine when the signal will trigger.

[r.flores]

Ok, thank you.

And do you know how can I somehow  at each successive trigger, output a different voltage (smiliar to a staircase function) in a analog channel?

[JBarrman]

Here is a community example of how to do a retriggerable output, I guess that you can start with that and mix it up with a case structure.

https://decibel.ni.com/content/docs/DOC-11304