Test and Measurement Forum

Pulse Count

Forum for discussing PicoScope version 6 (non-automotive version)

Pulse Count

Postby jpoleto » Wed Mar 12, 2014 6:36 pm

Is there a built-in function to count the number of pulses in a signal (i.e. rising edges or falling edges)? I have had some luck post-processing the scope data with an excel VBA script, but this is cumbersome and does not work in real-time. The total number of sample is also limited with this method due to Excel's limit on number of rows.

My signal is essentially a square wave. It is not a strictly periodic signal- it is a quadrature encoder output waveform, so frequency varies with respect to time. Because of this, I can't use the "measure frequency and multiply by time" method.

Any suggestions other than using built-in functions of Picoscope 6 are welcome.
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Re: Pulse Count

Postby Hitesh » Fri Mar 14, 2014 9:27 am

Hi jpoleto,

Which device are you using?

The USB DrDAQ has a function to count pulses if you are using the Software Development Kit to create your own application.

If you have access to MATLAB, you export your data to MATLAB file format and use the information in the following forum post in order to find the number of rising and falling edges:

http://www.picotech.com/support/topic13207.html

I hope this helps.

Best wishes,
Hitesh

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Re: Pulse Count

Postby jpoleto » Mon Mar 17, 2014 8:25 pm

Hitesh,

I am using a Picoscope 4424.

Unfortunately I do not have access to Matlab.

Is there an SDK that is compatible with the 4424 scope? Surely there are other customers with a similar need to count pulses. Is this capability something that the developers are working on?

Thank you for the prompt and helpful response,
John
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Re: Pulse Count

Postby Hitesh » Tue Mar 18, 2014 10:59 am

Hi John,

There is a Software Development Kit available for the PicoScope 4424 available from our software download pages:

http://www.picotech.com/software.html

In step 1, select the PicoScope 4424, and in step 2, please select the option for the 'Software Development Kit'

This contains USB drivers, dlls, a Programmer's Guide and examples for languages such as C, C#, Excel and LabVIEW.

I have updated the feature enhancement request for a Pulse Count feature.

Regards,
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Re: Pulse Count

Postby Eva zhou » Wed Aug 27, 2014 6:10 am

Hi Hitesh,

Have you added pulse count feature into the latest version of PicoScope 6? where? Recently, we have the same need too.


best regards

Eva
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Re: Pulse Count

Postby Hitesh » Wed Aug 27, 2014 8:02 am

Hi Eva,

Unfortunately, PicoScope 6 does not have a Pulse Count feature but I have added your enquiry to the feature request.

Thanks,
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Re: Pulse Count

Postby Patrick Hall » Wed Sep 10, 2014 12:54 pm

I am certainly interested in a pulse counting feature. I use a 3425 and measure line-driver (RS-422) quadrature encoder signals to and from various pieces of equipment in addition to analog signals representing velocity and torque (Industrial Servo Drives).
Presently the quadrature signals are only measured for quality verification, but I would welcome the ability to register pulse counts in addition to the velocity and torque on the same graph (Probe A/B quadrature signal, Probe C Velocity, Probe D Torque). Preferably the pulse count function would accept Single or Dual channel inputs configurable for use as dual independent counters (either increment or decrement) or as a single quadrature counter (A Lead B: Increment, B Lead A: decrement).
Best Regards,
Patrick
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Re: Pulse Count

Postby Hitesh » Thu Sep 11, 2014 8:52 am

Hi Patrick,

I have added your comments to the feature request.

Would it be possible for you to e-mail an example data file showing your waveform capture to support@picotech.com please? This is to help get an idea of the quantity of pulses in a capture and see if measurements can help in the meantime.

Regards,
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Re: Pulse Count

Postby diwmond » Tue Mar 24, 2015 11:27 am

We would also like to have this feature for single photon counting. Detectors gives a 6ns pulse for every photon with a 20ns deadtime, we would then like to count the number of pulses in a given time frame that exceed specified amplitude. Digital inputs on the 3000 series are perfect for this so a counting feature in software would be great.
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Re: Pulse Count

Postby that1guy » Tue Jul 14, 2015 9:26 pm

+1 for a pulse count feature.
It's very useful, especially when dealing with encoders.

IMHO, the picoscope software developers should look at all the measurements possible on a Agilent MSOX scope and aim for feature parity.

Hitesh, is this feature going to be added to the next version ... picoscope 7?
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Re: Pulse Count

Postby Hitesh » Thu Jul 16, 2015 8:28 am

Hi that1guy,

I've added your comment to the feature request for our Development Team.

If you have any further information about your application please post here or e-mail support@picotech.com and we can pass the information on.

Thanks,
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Re: Pulse Count

Postby Phil_S » Mon Nov 30, 2015 11:11 am

Hello,
Can I add my interest in a pulse count feature.

My application is for pulse counting on energy meters (gas and electricity), mainly checking that the gear is working OK.
A typical pulse is a square wave, amplitude 3.3-volts, positive-going from 0-volts, duration 1-second, about 20-seconds between pulses (variable), so easily seen over the very low noise.

As these are variably spaced i.e. not a fixed frequency, the suggested workaround of taking the frequency (24.12mHz between rulers in my case) and multiplying by the delta time in seconds (1hr:5mins:44secs, or 3944 seconds) yields 95 (approx) - the physical count of the pulses was 70 - so does not work here.

As there are 300 to 400 pulses in a session, physical counting is time consuming and generally inaccurate.

Thanks
Phil_S (Pico 2205A)
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Re: Pulse Count

Postby Hitesh » Tue Dec 01, 2015 2:36 pm

Hi Phil_S,

I have added your comments to the feature request.

One possible workaround might be to use a Repeat trigger to capture each pulse with the buffer counter giving you the number of pulses. In the Tools -> Preferences dialogue, set the number of waveforms to the maximum (10,000).

You can then use the Alarms feature to save the data to file when the buffer becomes full and then restart the capture:



Hope this helps,
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Re: Pulse Count

Postby jpoleto » Fri Sep 09, 2016 3:12 pm

Has there been any development on the pulse counting feature? Is there a beta version of the software which includes this feature?

-John
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Re: Pulse Count

Postby Martyn » Fri Sep 09, 2016 9:18 pm

The Beta software now has edge counting.
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