DAQmx Trigger property nodes does not list all properties, using gate for reading edges (2 issues)

[SCR-Dev]

Hi,

I've DAQmx 8.8.0, LabVIEW 8.5 as well as NI Suite 8.6.1.


In the course exercise for Data Acquisition and Signal Conditioning (course version 8.5) - exercise/solution 9-2 for PCI-DAQ has a vi called: Simple Edge Counting - Gated
It uses a DAQmx Trigger property node.
The properties used are - Pause.TrigType, Pause.DigLvl.Src, Puase.DigLvl.when

However, when I try to use the same property node form my MeasurementIO-NIDAQmx palette, I do not have these properties no matter how i re-size or search from RightClick>SelectProperty
Only properties I have are - ActiveChans, General properties>Chantype,  PhysicalChanName, Descr and IsGlobal

If I click the property in property node of the 9-2 tut vi, i cannot change, it says - No properties.

What is wrong with what I'm doing? Is it only available in 8.6 or even in 8.5?

Secondly, I'm trying to count / generate pulses depending on digital input. e.g. the machine sends a digital input and (as pre-configurred) DAQmx starts the function and ends when another digital input is sensed or the first one is reversed - i.e. using a gate. Can I achieve this with NI USB 6008?

I have with me NI USB 6008, NI USB 6501, NI USB 6009 and NI USB 6218. Which among these will facilitate?

Can I have a sample code or link please?

[Akshat Jain]

Hi Aniket,

               You have to use the "DAQmx Trigger Property Node" and not the "DAQmx Channel Property node".After putting "DAQmx Trigger Property Node" VI on to the block diagram, right click on "Start.Trig Type" and click on "Select Property" and not on " Property".Then select "More" and then select "Pause" and then "Trigger Type". Now you should expand the "DAQmx Trigger Prperty node" downwards so that all the three properties are visible.

This feature is available in LabVIEW 8.5 also!

For controlling the gate signal of the counter you just need a digital input into your system from a hardware.6008 can be used for accepting a digital input into the system and then this digital input can be used as a source in the "DAQmx Trigger Property Node".

Regards

Akshat Jain 

[SCR-Dev]

Hi Akshat,

Perhaps the wrong property node was highlighted in the last message.

However, I meant the trigger node while referring to my problem. I followed the steps suggested by you, I could see the property under 'more' but double clicking it wont bring it to use. See this picture (2.jpeg), I have marked the steps with the problem, 1,2,3,4,5

Secondly, about the VI from exercise 9-2, i beg to differ on opinion, but please guide me if I'm making mistake again:

I naturally require 2 separate pins to trigger  the counter and to actually count. The counter is a PFI and I guess, the trigger must be a PFI also. Then how can I use any digital input from 6008 when the only available PFI0 (ctr 0 or pin no. 29) is my counter / clock source?

 Any help will be much appreciate!

Best regards,

Aniket

[Akshat Jain]

Hi Aniket,

There are two more approaches for configuring the 'DAQmx Trigger Property Node' once you have placed it onto the block diagram.

1) Expand the "DAQmx Trigger Property Node" downwards as much as you can.All the 'Pause Trigger' related properties will be visible in the lower part.

2)After putting "DAQmx Trigger Property Node" VI on to the block diagram, right click on "Start.Trig Type" and click on "Properties" and not on " Select Property".Then select "More" and then select "Pause" and then "Trigger Type". Now you should expand the "DAQmx Trigger Prperty node" downwards so that all the three properties are visible.

Regards

Akshat Jain 

[Akshat Jain]

Aniket, 

A counter has got three pins (Gate, Source, Out).

In your current application, only Gate and Source are relevant.

The counter works in a way that whenever the Gate is high the counter increments on receiving pulses at the source pin.

So all you need to do is to connect the signal which you want to count at the Source pin and the triggering signal at the Gate pin.

In the DAQmx Trigger property node, right click on the 'Pause Trigger Source Property' and create a control. This control will show you a list of all the currently installed devices on the computer and their input pins.

You have to select the concerned device and the pin from the drop down.

Regards

Akshat Jain  

[SCR-Dev]

Hi Akshat,

I already know this theory! DO you have any NI DAQ at your disposal for experimenting?

I only wanted to know which pins I could use of the 6008 as trigger, I guess I cannot as it only has 1 PFI

[SCR-Dev]

No properties for me:

[Jerry_X]

It seems the trigger property node has filtered out the pause trigger attributes: the property by default filters out attributes that are not supported by the devices in the system.  To get all attribute to show up in the property node, you can right click on the property node and select "Select Filter...".  That should pop up a dialog to allow you to select between "Show Attributes For Configured Devices", "Show All Attributes", and "Show Attributes For Selected Devices".  You can select "Show All Attributes" to show all attributes including attributes that your device might not support, filter it to attributes supported by selected devices by selecting a list of devices in  "Show Attributes For Selected Devices", or show all attributes supported by all the devices currently in your system by selecting "Show Attributes For Configured Devices".

I am suspecting in your case, the device currently plugged into is 6008. 6008 supports only start trigger, so the property node by default filters the pause trigger attributes out of the list.  The list of devices you mentioned USB 6008, NI USB 6501, NI USB 6009 and NI USB 6218.  Looking at the spec sheet, I believe only 6218 supports pause triggers.

Hope this helps a little bit.