Pico Technical Support and Discussion Forum

leonidnk · Posted: Mon Jun 18, 2007 9:56 am Post subject: How to count pulses?

Hi,
I wish to count pulses from Kübler’s incremental encoder type 5802 (http://www.kuebler.com/english/pages/produkte/drehgeber/index_drehg_inkr_en.html, or http://www.kuebler.com/PDFs/leaflet/drehgeber/english/5802_en.pdf) and at the same time log data from load cell (http://www.wesmar.se/sok/documentation/brochures/revere/9363.pdf) with ADC-24. Please, help me to answer my question:

1. What is Digital I/O 4 bi-directional (3.3V CMOS) in ADC-24? May I use it to count pulses?
2. What is “frequency measuring function of Picolog” (see http://www.picotech.com/support/about1292.html)? May I use it to count pulses?
3. May I use a trigger mode (http://www.picotech.com/support/about884.html) to count pulses?
4. I am going to use Rotary Encoder. Pulse level is about 2,5 V. ADC-24 is able to log this voltage (http://www.picotech.com/support/about1579.html), next I can convert it to MATLAB readable format (http://www.picotech.com/support/about632.html)
and get a vector R=[R1,R2,…,Ri,…,Rn], where Ri is around 0,0 V, or is around 2,5 V. Then I can write a MATLAB script to recognize a jump of Ri and count amount this jumps. Amount of jumps = amount of pulses. What do you think about this idea?
5. In the same way I can get a vector with data logged from the load cell P=[P1,P2,…,Pi,…,Pn]. The value Ri was logged at Tri instant of time, the value Pi was logged at Tpi instant of time. Is Tri and Tpi are the same instant of time (Tri=Tpi)?
6. If question nr 5 answer is “No”, are all values of vector R and values of vector P have the same (constant) phase shift? With other words, is Tri-Tpi=Trj-Tpj?

Thank you in advance. Smile

ziko · Posted: Mon Jul 23, 2007 7:32 am Post subject:

Hi I believe we responded to you on email a while ago, I shall try and answer your query in a bit more detail.

1) The Digital I/O of the ADC 24 has the following spec

Output level, high > 2.40 V
Output level, low < 0.40 V
Input level, high > 2.20 V
Input level, low < 0.88 V

If you write your own software you can use it to count pulses, however this is not what it is intended for.

2)Frequency measurement, in PicoLog, only gives you a measurement of frequency, it works it out by looking at three cycles of a waveform and calculating the frequency from this, I have removed the post as it is not entirely correct.
3) Well you cannot count pulses using our software, however if you wish to write your own software you can trigger to count pulses.
4)If you write your own software you can save your data in whichever format you wish, that is assuming you have the know how.
5-6 I cannot answer these questions however if there is anybody out there who can answer this it would be appreciated.

Finally as I mentioned you would have to write your own software to achive your pulse counting, as I said before this is not the ADC24's intended use, what you really need is a hardware counter, there are plenty of manufacturers out there who specialise in this field. If someone knows anything about hardware counters please feel free to give a helping hand, much appreciated.

Kind regards

Pico Technology

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