NI USB 6000 Hardware

[pk4]

I have  NI USB 6000 hardware. I want to generate a 0-5V pwm signal from the digital i/o pins. Is it possible to do so using that hardware? I assume since its digital its only can pwm 0-1 only. Please correct me if I am wrong as I am new to this.

[RavensFan]

According to the specs, the digital I/O is software times.  http://sine.ni.com/nips/cds/view/p/lang/en/nid/211872

So I'd say no, you are not going to be able to create a PWM signal unless the pulse widths are long enough that software timing can generate them.  (Such as ON, wait 5 msec in code, OFF wait 10 msec in code, repeat, for a 33% pulse width at 15 msec per cycle.)

[Wolleee]

The voltage on the ni usb 6000 is going to be -10-10V so your pwm is going to be 0-10 on or off right? Otherwise it seems possible to me.  Here is a link to get you started in labview.

NI PWM Example

[Edoit] Ravensfan is correct if it is software timed though.  You will need to do the timing in software.

[pk4]

I read the data sheet it says that signals of +-10v can be measured on the analog input side. So I assume the PWM of 0-10 On/Off can be generated using the digital I/O pins. What does software timing exactly means here? is it like a delay between the signal when its rising and when its falling?

[GerdW]

Hi pk4,

so you read the AI will read ±10V signals - and from this fact you assume the (unrelated) DIO will also work with ±10V???

Why don't you read the specs for the DIO pins? They are very clear with mentioning TTL and LVTTL! Also there is a clear spec on DO capabilities…

What does software timing exactly means here?

This means there is no hardware-driven clocking for those DIO pins available: you cannot set a sample rate to read DI signals at a certain rate. All you can do is reading/writing one sample with simple software timing. Due to this the DIO pins allow only ~100Hz samplerate…

[pk4]

My bad. Thanks for correcting me. So in the data sheet I see Digital Output( Active drive) and Digital Output( Open collector) what exactly is the difference?. The digital input has a voltage range of 0-5 V.

[GerdW]

Hi pk4,

the DI allows TTL levels (0-5V), while the DO works with LVTTL levels and only tolerates TTL levels.

When you don't know, what an "open collector" is, you should read Wikipedia or a good electronics book!

For a first glance you could also read the manual of your DAQ device - you surely did this before, don't you?

[RavensFan]

Basically whether a digital output actually outputs the current at that voltage or absorbs it.  Google for the differences between source and sink for digital I/O.

[pk4]

Hi GerdW,

I am a Mechie, but thanks I would surely read about it. Yes I did read it but it was a different one and dint specify so many details.