Monitor sensors whose output is PWM

What do you need Phidgets to do for you?
donireland
Fresh meat
Posts: 3
Joined: Mon Jun 02, 2014 9:39 am
Contact:

Monitor sensors whose output is PWM

Postby donireland » Wed Jun 11, 2014 3:25 pm

I need something I can interface sensors whose output is PWM (monitor 6 at once). I could interface that direct to a PhidgetInterface kit through a USB hub and be able to "talk to" or monitor using VBA.

Right now I am trying to "rig" something that may/may not work.

Anyone have a suggestion?

User avatar
Patrick
Lead Developer
Posts: 3099
Joined: Mon Jun 20, 2005 8:46 am
Location: Canada
Contact:

Re: Monitor sensors whose output is PWM

Postby Patrick » Wed Jun 11, 2014 5:15 pm

What about the PWM are you trying to measure? Duty cycle or frequency?

If You want to measure the frequency, you could use the 1054 frequency counter.

If the voltage is 0-5 V and the frequency is below ~30-40Hz then you can monitor it directly with an interfacekit digital input.

-Patrick

donireland
Fresh meat
Posts: 3
Joined: Mon Jun 02, 2014 9:39 am
Contact:

Re: Monitor sensors whose output is PWM

Postby donireland » Mon Jun 16, 2014 7:06 am

I need to measure duty cycle. When I was first handed the project, it was presented as Frequency. So, I bought 3 frequency Counters (6 sensors). Turns out that I truly need duty cycle.

I am going to try the Interfacekit Digital Inputs simply to see if that will work and what I get for a response from the system.

I was able to locate a product that I know will work (not a Phidget unfortunately). It connects via USB and can be programmed via VBA. So, I can at least use the same interface I was planning.

Tech support pointed me towards an encoder interface. But, I am not certain how that would have to be wired up to work. Since I have a device in hand right now, I think the immediate need is covered. However, if there was a way to do this all within Phidgets, it could be really helpful (I don't get to keep the device I have and will have to replace it eventually.....)

Any other suggestions?

Thanks

User avatar
Patrick
Lead Developer
Posts: 3099
Joined: Mon Jun 20, 2005 8:46 am
Location: Canada
Contact:

Re: Monitor sensors whose output is PWM

Postby Patrick » Tue Jun 17, 2014 9:07 am

Depending on the frequency, you may be able to measure the duty cycle with an ADC input - the 8/8/8 inputs are sampled at 1kHz, but allow for data rate averaging out to 1 second.

-Patrick

donireland
Fresh meat
Posts: 3
Joined: Mon Jun 02, 2014 9:39 am
Contact:

Re: Monitor sensors whose output is PWM

Postby donireland » Tue Jun 17, 2014 11:23 am

I have been given two of our sensors to try the setup. One is programmed at 155 Hz and the other is at 263 Hz. So, It does not look like the digital inputs on the interface kits will work.

Are you just suggesting to run a simple conversion on the PWM output for to measure the resulting analog signal? I thought of that but was told that we needed to keep the digital signal in tact to avoid any conversion errors. There is a fairly tight tolerance on the product and all tolerances that would lead to output variation need to be eliminated, reduced or recorded.... So, if there is not a direct way to measure and report it, I need to use the alternate item I have.

Hopefully, there will eventually be something in place to do this directly. Knowing the current path my organization is taking, it would be incredible useful for us....


Return to “Phidgets”

Who is online

Users browsing this forum: No registered users and 5 guests