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Hard-coding USB-6501 to use "Active Drive" mode instead of "Open Collector"

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Hello everybody out there using NI devices,

 

The device I would like to trigger with my NI USB-6501 requires to use the digital output ports in "active drive" mode (instead of "open collector" which is the other option:

It only reacts if I choose "active drive" in the drop-down menu of the digital output test task, which I generated in NI Measurement and Automation eXplorer (MAX).

The available current in "open collector" mode doesn't seem to be sufficient to trigger my device.

However, the "open collector" mode seems to be used by default, because the USB-6501 box fails to trigger my device in all other situations (i.e. outside the specific test task in MAX where I can set "active drive" mode).

 

Is there a way how I could permanently make "active drive" the default mode on the USB-6501 box?

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You cannot change the default mode, typically you configure the output drive type as soon as you create a DAQmx task and the configuration retains throughout the lifetime of the task.

 

NI MAX based soft panel interactions persist only as long as the panel is active.

Santhosh
Soliton Technologies

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Thanks for your answer.

 

The USB-6501 is controlled by an existing, program for Microsoft Windows, which I probably cannot modify.

Is there a way to nonetheless enable the "active drive" mode?

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Ideally, you need to do that inside that application. Even if you configure the Drive type outside the application, there is no guarantee that your other windows application does not reset the USB 6501. You can also externally add a translation circuit that way it will always work.

Santhosh
Soliton Technologies

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Sorry for still being a bit confused:

 

I tried to carefully read the article "Configure NI Device to Be Open-Drain or Push-Pull" (https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000YHwFCAW&l=de-AT) in the knowledge base.

 

It mentions:

"If you are using NI-DAQmx Base, you can set this property in the NI-DAQmx Base Configuration Utility. There is no way to programmatically set the output drive setting in NI-DAQmx Base."

 

This would be good news for me, but I would not know of a NI-DAQmx Base Configuration Utility.

 

Sure, if the application actively resets the configuration of the device, this would not have any effect.

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Accepted by topic author SausageDog

I would also feel inclined to make a simple buffer circuit to handle your situation.  Single chips with some support components (capacitor on the power rail for instance) would be all you need.  You may even find a board ready to use on Adafruit.


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Thanks for all the hints so far.

 

I was wondering whether there is a NI USB Box, which generates stronger pulses straight away.

Developer and engineer time would probably be more expensive than an existing solution.

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@SausageDog wrote:

Thanks for all the hints so far.

 

I was wondering whether there is a NI USB Box, which generates stronger pulses straight away.

Developer and engineer time would probably be more expensive than an existing solution.


I agree that developer and engineer time is more expensive. There are other USB DOs in NI's lineup with better drive current, what are your requirements?

https://www.ni.com/en-us/shop/hardware/products/digital-io-device.html

santo_13_0-1676135512088.png

USB-6525 has the highest drive current of 500mA  but you're limited to just 8 outputs + 8 inputs per device.

 

Santhosh
Soliton Technologies

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Thanks a lot. 8 outputs would be sufficient (and inputs would actually not even be necessary).

 

Are there also USB multifunctional I/O boxes, which would provide stronger output pulses in comparison to the USB-6501?

I had tried USB-6008, but it also didn't seem to provide strong enough output pulses.

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Typically for a Digital Output line, 10mA is more than enough to drive signals between systems. Anything larger than 10mA is no more a digital output but rather a close to SSR realm.

 

What are you trying to drive, why a stronger drive is required and what is your expectation?

Santhosh
Soliton Technologies

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