Author Topic: PWM  (Read 10546 times)

dan

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PWM
« on: August 26, 2005, 12:04:23 PM »
Hi,

I have some questions
1. There is any way that 20000pps can be increase?
2. Do you have any plans to incresed this no and when?
3. In the same program I will have different segments that in sometimes required only one chanell and I plan to use 20000Hz (more will be nicer) and in other sections I will need use 2 channels.
I just want to make sure that using two chanells for some segments will not limit all the sections to 10000pps.

Thank you,

Dan

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Re:PWM
« Reply #1 on: August 26, 2005, 11:38:57 PM »
Are you referring to the PWM outputs? The PWM output frequency is fixed at 8 possible frequencies for T100MD+ or T100MX+ PLCs. The maximum frequencies is 32KHz.

If you are referring to stepper pulse output, then please limit the stepper pulse frequency to below 10KHz for best performance. The CPU is unable to generate very square pulses at 20000 pps so it may not work at this frequency.
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Joel Moore

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Re:PWM
« Reply #2 on: August 30, 2005, 01:26:49 PM »
My circuit design skills are pretty pathetic but an idea occurred to me.  I wonder if there is a simple circuit (or even not-so-simple) that could take a single pulse from the Triplc and convert it to two pulses, thereby effectively doubling the maximum frequency?  Maybe a 555 timer could help here.  I guess the trick would be ensuring that the single pulse from the triplc is accurately divided in half and obviously some care would have to be taken to avoid degrading the pulse train.

Just an off-the-wall idea I thought I'd throw out there.

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Re:PWM
« Reply #3 on: August 30, 2005, 01:48:35 PM »
It is easy to half the frequency of a square wave pulse by feeding it through T flip flop, but doubling the frequency is a different matter. I doubt it is easy to do. But if anyone has good idea we would like to hear about it too.
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