CarveOne- Good to hear you received the high-current SuperPID all ok in the airmail.
Khalid and Al_the_man- Thanks guys for the hardware suggestions re direct connection to Mach3 via the PC. I have some options already under consideration for future revision of the Super-PID.
RedskinsJBS- Thanks for your order! Also you are right about the semi-log system used for the Super-PID speek knob, more info below.
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Re Mach3 controlling the RPM;
I'll try to break this down to show where it's at at the moment.
1. The Super-PID was designed so it can be operated from a 0v-5v analog voltage to control the RPM. This is standard, similar to many VFDs etc.
2. If you already have a 0v-5v analog control voltage it can be connected instead of the Pot Output wire "PO" and will control the speed. However this raises 2 issues;
A. The 0v-5v range will produce 5000-30000 RPM result.
B. The 5000-30000 is semi-log, not exactly linear.
Both A and B were done deliberately to give the very best possible "feel" of the Super-PID speed knob. Believe it or not my very first pot code was linear; 5000-30000 with 17500 centre of the dial. But it sucked, the low RPMs (that are so critical for tuning cutting) were very touchy on the dial and the 20000-30000 RPM range took up half the dial. Imagine turning the knob 54 degrees at the bottom giving a 100% RPM rise, but the same 54 degrees near the top of the dial gives only a 20% RPM rise! That's the trouble with "linear by RPM" it is terribly clumsy on a speed dial.
So I deliberately coded the pot "feel" to give the very best usability, with a graded semi-log effect so turning the knob 5 degrees near the bottom gives a similar perceived RPM % change as turning the knob 5 degrees near the top. I even expanded the range a little around 10000 RPM giving it even better tunability there. This was tweaked over weeks of me testing and doing cutting jobs etc.
So, for Super-PIDs already in service; you can use a 0v-5v analog speed control voltage but it will give 5000-30000 RPM range and semi-log (so centre dial is about 11000 RPM).
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Hardware options to get 0v-5v from Mach3;
1. Connect the PWM output from Mach3 through any CMOS logic chip (like Khalid's circuit in post #192) then through a 47k resistor and 100uF cap to filter the PWM. Total cost under $2 but is fiddly and you need electronics skills.
2. If you already have the Mach3 PWM signal from a CMOS IC (not direct from the parallel port) but from a buffer IC on a break out board, you only need the 47k resistor and 100uF cap. Many people's break out boards are already set up like this, with CMOS buffers.
3. Or use a third party module to convert the Mach3 PWM to analog 0v-5v signal. Ger21 already posted a link to two products that do this, in post #38. These may or may not need the additional 47k and 100uF filter parts.
4. Gecko G540 users can use a couple of 22k resistors to turn its 0v-10v output into 0v-5v. Then you still connect a 47k resistor and 100uF cap.
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Firmware solutions for now.
I can offer a re-programming service for existing Super-PID users, to make your speed control go from 0-30000 linearly. Note that under 5000 RPM will still be fixed to a 5000 RPM minimum, but the 0-30000 RPM will correspond with Mach3. Please remember this will make your speed control knob feel awful, so this option is best if you want to use Mach3 for speed control only.
I'll discuss with Val the possibility of offering this firmware as an option with new SuperPID purchases. It may add a couple of days to your order time.
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Future product Mach3 compatibility.
For the next PCB revision it looks likely we will add some extra hardware to allow direct PWM input into the Super-PID. This may add a few dollars to the price.
I can also add a switch option to allow changing between 0-30000 linear speed and 5000-30000 semi-log speed, so the user can use either system as desired.
The next PCB version will be some months away, depending on sales. I'm sure Val will post any new product updates well in advance.
Sorry for the long post!