PWM output setup

[Garyhlucas]

I want to use a PID loop with a PWM output to drive solid state relays for temperature control. No problem setting up PID but after carefully reading the help file I still can?t figure out how to get to the PWM screen shown in help!

[franji1]

Is this on BRX?

[Garyhlucas]

Sorry about that!

Yes it is a BRX.  I am going to use the BRX to control the bed and nozzle heaters for my 3D printer add-on for my CNC mill/lathe/3D printer.  Should work pretty good as it is quite fast, 300 ipm without a problem, and the build envelope will be an 18" cube.  Every since I gave my grandson a 3D printer for Christmas I realized I need to finish my version for bigger stuff.

Struggling with this project right now because despite having 45 years experience doing control panels I built this one without doing a wiring diagram first.  Five days cutting bundles, poking at connections, ringing out circuits and I am still not quite sure I have it all sorted.

Experience, it is how you recognize a mistake when you do it again!

[BobO]

For BRX PWM: Go to the HSIO page. Select the PWM you wish to configure. Click enable and specify the output you want to associate with the PWM. Click OK. Done.

To use: The PWM created a structure based on your device name. Turn on the .Enable field to start running, and control the duty cycle through the .DutyCycle field. You can set the period through the .Period field, and change the period scale from microseconds to milliseconds with the .PeriodScale field.

If you are controlling AC, the TIMEPROP instruction will work just about as well though.

[Garyhlucas]

Thanks,
Yes it is AC so I?ll look Timeprop as well. I want to learn about both as I may have another use for PWM.

[BobO]

At 60Hz, the appropriate PWM period will be long enough that normal scan instructions like TIMEPROP can do what you need. The PWM hardware can be used, but isn't necessary.