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Messages - Hminx

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Technical support / Re: PID control of two contradictory PWM signals
« on: February 27, 2024, 11:49:17 PM »
Hi Gary
Thanks for that, what you suggest makes perfect sense and should do the trick.
i will try that as soon as my replacement FMD1616 turns up as yesterday when I turn the machine on the PLC refused to respond for a while
then powered up the first four outputs plus RTC, pause, and error LEDs   lit up, plus it would no longer communicate  :(   Unlike the old T100MD
series these aren't easy to plug in a replacement chip and get it back into service maybe a marketing strategy  ;)
 Cheers Pete

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Technical support / Re: PID control of two contradictory PWM signals
« on: February 22, 2024, 12:25:55 AM »
  Thanks for the feed back, I thought that this may be the case but was hoping for an easier work around, but such is life  :)
FYI the two PWM  signals is quite common on heavy automotive diesels, from the foot throttle to the engine ECU .   Normally we would use the auxiliary external throttle input for engine speed control, but this is not an option in this case.

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Technical support / PID control of two contradictory PWM signals
« on: February 19, 2024, 01:08:18 AM »
Hi all

Been a few years since last used trilogi stuff but have a few up coming projects that I plan to use FMD1616-10s. The issue I'm stuck on is
how to control the  speed of an engine powering a large vacuum pump, the input signal uses two PWM signals acting together

   1.        Idle - full throttle           81 - 27 %  PWM     @ 5v  200 Hz
   2.        Idle - full throttle           17 - 73 %  PWM     @ 5v  200 Hz

The  vacuum pump is direct driven at engine speed, 1400 rpm and in this case, the speed signal at this speed is 23 Hz, and scoping the throttle signals while operating the throttle manually indicates signal 1 at about 53% and signal 2 at about 46%.  Ssooo.... what I need to do is work out some method of PID control over two control signals that move in opposite directions.

I would be quite willing to have a crack at sorting out a single channel control but the two opposing signal thing is a bit beyond me so any help would be greatly appreciated

Cheers Pete

Oh by the way, I assure you I'm not a student asking some one to do an assignment I should be doing myself  ;)





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