PWM gen

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05 Dec 2018 10:14 #121856 by Sytreca
PWM gen was created by Sytreca
Hi everybody

I'm trying to create a PWM. i try to do this on a 7i66 output.
Is this possible?
I encluded my hal en ini file. In the end i want to use this pwm to control a Spindle.

With kind regards
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05 Dec 2018 10:32 - 05 Dec 2018 10:33 #121857 by Clive S
Replied by Clive S on topic PWM gen

Hi everybody

I'm trying to create a PWM. i try to do this on a 7i66 output.
Is this possible?
I encluded my hal en ini file. In the end i want to use this pwm to control a Spindle.

With kind regards


I am still a novice this, but looking at the hal file you seem to have these two addf pwmgen.update servo-thread and
addf pwmgen.make-pulses base-thread

Do these need to go between the read and write at the top with the others?
Last edit: 05 Dec 2018 10:33 by Clive S.

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05 Dec 2018 13:47 #121870 by PCW
Replied by PCW on topic PWM gen
If you are using a 7I66 output you will be limited to the servo thread as the PWM base frequency. This means that to get 1% resolution assumimg a 1 KHz servo thread, you would be limited to 10Hz.

To make filtering easier its probably better to chose PDM rather than PWM

Assuming 1 KHz servo thread, 50% duty cycle PWM at 10 HZ would be 50 ms on 50 ms off, 50% duty cycle PDM would be 1 ms on 1 ms off...

PDM is selected by setting the software pwmgen components frequency to 0

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05 Dec 2018 14:12 - 05 Dec 2018 14:13 #121872 by Sytreca
Replied by Sytreca on topic PWM gen
Is it still possible to create a analog signal (0-10V) with this PDM signal?
Because my VFD only accepts 0-10V or 4-20mA.
Or do i need to look for another solution?
Last edit: 05 Dec 2018 14:13 by Sytreca.

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05 Dec 2018 14:36 #121875 by andypugh
Replied by andypugh on topic PWM gen

Is it still possible to create a analog signal (0-10V) with this PDM signal?
Because my VFD only accepts 0-10V or 4-20mA.
Or do i need to look for another solution?


Both PWM and PDM can be converted to analog voltage by the same low-pass (resistor + capacitor) converter.

(The VFD might well be happy to operate on PWM / PDM without a filter)

Is there any possibility of controlling the VFD with Modbus?

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05 Dec 2018 14:39 #121877 by andypugh
Replied by andypugh on topic PWM gen
What is controlling the 7i66? Perhaps you could add another smart-serial card, or use another interface?

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05 Dec 2018 14:52 - 05 Dec 2018 14:55 #121880 by Sytreca
Replied by Sytreca on topic PWM gen
There is a possibility to connect serial with RS323,RS485 or RS422.
The 7i66 is connected to 7i44 and this is connected to 5i23.
But all the ports on 7i44 are most likely gonna be used up.
On the 5i23 P3 is still available.
Last edit: 05 Dec 2018 14:55 by Sytreca.

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05 Dec 2018 14:59 #121882 by andypugh
Replied by andypugh on topic PWM gen
You can probably arrange to have a high-frequency (up to MHz) PWM generated on one of the 5i23 pins.

Alternatively the 7i83 would do what you want, but seems overkill for an individual analogue output: store.mesanet.com/index.php?route=produc...83_88&product_id=122

It's a pity there isn't a single-channel smart-serial version of the Spinx1
store.mesanet.com/index.php?route=produc...t_id=205&search=spin

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05 Dec 2018 15:02 #121884 by Sytreca
Replied by Sytreca on topic PWM gen
It's a commander CD75-750. i don't know with which component this corresponds.

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