Retrofitting a 1986 Maho MH400E

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06 May 2018 15:05 #110278 by RotarySMP
Hi John,

I decided not to get a 7i83, as I have enough spare inputs on the 7i77. I am multiplexing the control panel buttons, so only 10 inputs are used for the 24 switches. I also want to make a pendant, and think I can just squeeze everything into the existing 7i77 and 7i84 I/O.

The switches feel pretty good. The travel is about 1-2mm. There is no positive click, and the 3D printed buttons can hang up if the force is too off axis. I'll see how this works, and if they are a pain in use, I can back them up with some coil springs. The seminar hotel next to my work has pens with the idea spring in them. Our company sometimes has seminars there, so I havest the left over pens just in case. I kind of plan to CNC mill some aluminium buttoms once the MAHO is running. We'll see if that happens.

Mark

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06 May 2018 17:39 #110281 by drimaropoylos
Hi, i haven’t quite understand how multiplex works on the 7I77. I thought that multiplex can be done only with 7i83 or on some Pokeys style dedicated hardware. The 7I77 card can sense short circuit between the inputs?

John

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06 May 2018 17:46 - 06 May 2018 17:53 #110282 by PCW
Replied by PCW on topic Retrofitting a 1986 Maho MH400E
Not sure what the question is...
edit:
Oh I think I see, you mean how can you multiplex inputs?
This can be done all in hal with almost any kind of I/O device
to expand the number of inputs though diodes may be needed externally
to prevent "sneak paths"

The LinuxCNC component matrix_kb implements input muliplexing using any kind of I/O device
including parallel ports
Last edit: 06 May 2018 17:53 by PCW.
The following user(s) said Thank You: akb1212, drimaropoylos

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06 May 2018 17:56 #110283 by drimaropoylos
When you press a bouton in the matrix keyboard system, a connection from one input to another is made. The 7I77 can sense a connection between inputs?

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06 May 2018 18:08 - 06 May 2018 18:09 #110284 by PCW
Replied by PCW on topic Retrofitting a 1986 Maho MH400E
On a multiplexed kb system there is a matrix of outputs and inputs
so for example a 64 key matrix could have 8 outputs and 8 inputs
with the key switches at the intersections. Typically the 8 outputs are driven
one at a time and the 8 inputs read every time a different output is energized
Last edit: 06 May 2018 18:09 by PCW.
The following user(s) said Thank You: drimaropoylos

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06 May 2018 18:27 #110286 by drimaropoylos
Again, thank you for the response.

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07 May 2018 00:50 #110304 by J Green
"I decided not to get a 7i83, as I have enough spare inputs on the 7i77" Oh No ! :ohmy: What about the Tool changer ? What about the electronic tool probe/part probe ? What about the "A" and "B" axis? What about the Blinking Lights if the machine chokes on a job ?:laugh:




John --- I bet Mark is just showing us a bare bones proof of concept conversion and holding back what is really going on--:silly:

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07 May 2018 05:54 #110310 by drimaropoylos

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07 May 2018 07:18 #110312 by RotarySMP
LMAO!!! MAHO made some real Rube Goldberg style mechanisms for tool changing didn't they.

A fourth or fifth axis shouldn't need much I/O, if you connect an analog motor driver and encoder to one of the six analog control loops, and then should only need an input pin for an index.

A tool probe is also only a single input pin. I was intending to have a connector on the pendant, and plug a probe into it.

John,
My plan of the MatrixKB in this post...
forum.linuxcnc.org/12-milling/33035-retr...00e?start=310#103928

I finally got the last buttons printed, and could assemble the lower button carriers. Then continued with the button wiring. I'd forgotten how time intensive wiring is.


Sorry about the photo rotation. I rotated this when I cropped it, and all the windows programs show it with the correct orientation, but it the orientation seems to be ignored by the forum software.
Mark
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