Messages

861

General Mach Discussion / Re: Manual pulse encoder & mach3

« on: January 25, 2022, 06:53:14 PM »

Hi,
perfect, you should see the output change every second click...and thats exactly what you see.

In absence of the BoB the output would be 12V, but with the BoB its dragged down to just a little over the BoB supply voltage.
This is not ideal, but it works. You are relying on the output impedance of the A/B outputs AND the input diode clamps of the BoB
to ensure the voltage translation.

When I measured the output impedance of the MPG I did so very quickly.....so I can't be 100% about it being 10kOhm, although I
suspect it would be close. Likewise we cannot be sure of the input diode clamps.....I would guess we are seeing the ESD protection diode of
the buffer IC operating, and most engineers would say that relying on ESD diodes is a bad idea......even if it does work!

Craig.

862

General Mach Discussion / Re: Manual pulse encoder & mach3

« on: January 25, 2022, 06:42:33 PM »

Hi,
having had personal experience with these particular model MPGs, the outputs are 12V/0v. They are both sourcing AND sinking,
ie totem pole outputs, with an output impedance of about 10kOhm.

By all means test the outputs.....but it's not until you hook it up to the BoB that you will know if the outputs have enough current authority to
swing the BoB inputs. Also you won't really know until you try whether you have to limit the outputs to 4.7V or whether the input impedance of
the BoB inputs will 'drag' the incoming 12V down....to....what I wonder?

Craig

863

General Mach Discussion / Re: Manual pulse encoder & mach3

« on: January 25, 2022, 06:03:33 PM »

Hi,
Yes, the 0V of the external supply will have to be referenced to the COM of the BoB.

I suspect the that output impedance of the MPG is such that the inputs of the BoB will swamp the 12V A/B outputs down to 5v of the BoB,
Its not very elegant but it should work. Using Zeners and resistors is preferable.

Craig

864

General Mach Discussion / Re: Manual pulse encoder & mach3

« on: January 25, 2022, 05:49:55 PM »

Hi,
your making progress....but why is there 36V showing from time to time.

Do you have the 0V from your 12V external supply connected to the 0V COM of your BoB?. They will need to be connected.

Craig

865

General Mach Discussion / Re: Manual pulse encoder & mach3

« on: January 25, 2022, 04:39:05 PM »

Hi,
what the hell, in your video you showed the outputs varying, in probably the correct pattern but to about 50mV.....what gives?. The input to the BoB
needs to be 4.5-5V???

Don'y worry about the switching pattern....that will look after itself. Just hook one input, say A, to the BoB and measure the voltages as it turns on and off, and report.
Be careful to note whether you are seeing 'volts' or 'milliVolts'.

Craig

866

General Mach Discussion / Re: Manual pulse encoder & mach3

« on: January 25, 2022, 02:40:22 AM »

Hi,
have you supplied the encoder with 12V?

If so the outputs A & B will also be 12V or close to. Its probably a good idea to use a 4.7V Zener diode on each output to ensure that no damaging
voltage (that is over 5V) gets into your BoB. Having said that the outputs are both fairly high impedance and are not likely to damage the BoB,
so the Zeners are precautionary.

Then hook the MPG outputs (Zener limited) to the BoB and then to Mach. You may need to reverse one or even both outputs (by changing active high/active low)
to ensure that Mach correctly determines which way you are spinning the MPG.

Craig

867

General Mach Discussion / Re: Mach3, Windows and Parallel Port Usage.

« on: January 23, 2022, 05:06:56 PM »

Hi,

Has anyone tried the autoleveller program to surface map for cutting PCB?  Looks interesting.

I uses it daily and have done for seven-eight years, first with Mach3 and Windows 7/parallel port and for the last seven years Mach4/ESS. I'd be lost without it.

Craig

868

Mach4 General Discussion / Re: Mach4: Log Axis movement time.

« on: January 21, 2022, 05:31:27 PM »

Hi,
that's a good workaround, and a very clean & lean piece of code in the PLC script, all-in-all its a good solution to OP's query.

Craig

869

Mach4 General Discussion / Re: Glitch on X movements

« on: January 21, 2022, 05:21:08 PM »

Hi,
have attached a couple of pics of my two BoBs.

I will eventually get around to making both these boards anew. The IO board will have a minor modification to do with the PWM output circuit.
The Servo board will have the dual OpAmp's replaced with a dedicated line driver IC (AEIC-7272-S16).

Otherwise the board layout will stay the same, namely two boards 60mm x 180mm.

I am giving some consideration to making one single board which would allow the ESS to sit atop the BOB in a similar manner to the MB3.

Craig

870

Mach4 General Discussion / Re: Mach4: Log Axis movement time.

« on: January 21, 2022, 12:57:41 AM »

Hi,

It does matter as far as i can see.

Rubbish, if its out, even by quite a margin, the axes will still get lubed....and thats all that matters.

I was just saying it's a PITA because the person asking is basically looking for a stopwatch solution.

We agree there, a genuine stopwatch solution would not be easy, if its even possible, and what would all that extra effort and CPU processing get you...
not  much.

Craig