Daqmx Task, controlling I/Os independently with labview software

[rlg34584]

I have a NI 6512 (64 source I/O PCI) and I am trying to determine the best way to control each I/O individually. I am using the 6512 to control relays and don't need them all open or closed at the same time. I realize that I will probalby have to do software timing, but I thought I'd ask to see if there is another way and if so, what is the best aproach.

[Mark_E]

Welcome to the discussion forums, rlg34584!

Yes, the 6512 is controlled via software-timing. A quick way to get started is to check out the shipping examples. In LabVIEW go to “Help -> Find Examples” to open up the Example Finder. In the lower left, you can limit the examples by your particular hardware. A good example that I was looking at is called “Write Dig Chan.vi” found by selecting “Hardware Input and Output -> DAQmx -> Digital Generation. The Data to Write control can be expanded downward to expose more than one port, thus giving you access to additional lines. This VI allows you to output a high or low signal to the corresponding lines.

Another great reference is the 651x User Manual.

Hope this helps.

[rlg34584]

This looks like it'll work great. Thanks.

[Defer]

I'm working with 6512 too.

Do you know if it's possible generated stable square wave using this board. I ask this because i did it using Labview but it seems that at frequency of 100 - 200 Hz the square wave isn't stable and depend from the program that running on PC in that moment.

For example if you move one window on the screen with the mouse you can see with the oscilloscope a deviation of the 6512 frequency output.

[Mark_E]

Welcome to the discussion forums, Defer!

The effect you’re seeing is due to the fact that the board is software-timed, meaning that it’s very much dependent on when Windows allows the program to communicate with the hardware (6512). If Windows decides some other process has a higher priority, then LabVIEW may suffer slower response time.

The best option to achieve deterministic generation is to purchase a device that supports hardware-timing. With a hardware-timed device, the data is sent to the hardware and can be regenerated from the device until it receives a new command from software to change it. That way, no matter what’s happening with Windows, it’ll run contently until it receives notice to do something differently.

If you would like to purchase a hardware-timed device, please visit ni.com/contact.

[Stephen Turner]

What boards with hw timing might be related to this one?  The engineer on my project picked this because we want these lines to be able to turn on an off a 24V power supply.  I need an accurate pulse, and I am beginning to think we bought the wrong product!

[tnek]

Hi Stephen,

There are a few modules in the cDAQ line which will are hardware timed and will be able to accomodate the voltage levels are looking for. If you browse the products by certain features such as digital hardware timing. Again, if you would like to talk to somebody about this, you can contact your technical sales representative here.

Regards,

Kent

Applications Engineer