PWM Issues

[JvP79]

Hi all, I’ve been reading on this forum for some time. And have now finally gotten around to assemble my workbee (duet2 WiFi with RRF 3), which has been sitting in its box for quite some time.

All is well with the workbee and I have just installed an AMB spindle with digital speed control (am in the process of installing this). In order to have full control over the speed I also installed a PWM ([url= https://www.amazon.co.uk/gp/product/B0789738RC/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1]this one[/url]). After some tinkering all seems well, that is the jumper setting is correct (24V), it has powersupply of 24V and the lemon signal is also correct (as far as I can measure with my multimeter).

The problem however is that there doesn’t seem to be any output on the A0 & GND pins.

I’m a novice in regards to elektronics, but do I have a defect PWM? Or do I have to adjust the frequency of the signal? Or something else?

Thank you for your input and comments!

[alankilian]

@jvp79

• Where do you have PWM- and PWM+ connected to the Duet?
• How are you configuring that pin as a PWM pin?
• How are you setting the PEM value for that pin?

[JvP79]

@alankilian

Thank you for your reply!

I have followed the guide from ooznest (https://learn.ooznest.co.uk/Guide/Connect+a+AMB+Kress+or+Mafell+spindle+with+digital+control/161). I have followed the guide to the letter and checked it to be correct.

So I am using the heater E0 for the PWM in and indeed it has been assigned as such by the firmware from ooznest. As I mentioned it nicely puts out a voltage between 0 & 10V depending on the commands inputted.

Which is done either by an input command (M3 …) or directly from the desktop control panel from ooznest where they have added preset buttons/macro’s.

Edit: just noticed in my first post the pwm in signal was corrected to “lemon”.. thx apple

[cjm]

@jvp79 It’s probably worth using your multimeter to check the voltage between pin 3 (multimeter red lead) and pin 4 (multimeter black lead) of the PWM module.

With the power on, this should read +24V.

[JvP79]

@cjm Indeed that is correct it reads 24V.

[cjm]

@jvp79 Just as a sanity check, you're seeing + (positive) 24V and not - (negative) 24V?

[JvP79]

@cjm yes that is correct I’m seeing positive 24V

[cjm]

@jvp79 Hmmmh...

Your measurements indicate the converter is connected and being powered correctly so what else would stop it working?

Perhaps the PWM frequency is outside of the range of the converter? Looking at the Ooznest instructions I see the following command is used to configure the PWM:

M950 R0 C"e0heat" L0:25000 Q100

This sets the PWM frequency to 100Hz, whereas the quoted minimum frequency for the converter is 1KHz, so perhaps try adding an extra zero to set the PWM frequency to 1KHz like so:

M950 R0 C"e0heat" L0:25000 Q1000

Otherwise, it sounds as though the converter might be faulty...

[JvP79]

@cjm before I changed the frequency in the code I replaced the pwm board (just received the replacement). And presto it all worked!

So problem solved!

Thanks for all your input!

[cjm]

@jvp79 Good news!