Re:My CNC Retrofit Project/Don't cut wires!

Message: 9
Date: Fri, 15 Oct 1999 09:58:28 -0500
From: Ray Henry <rehenry@...>
Subject: Re: My CNC Retrofit Project/Don't cut wires!


The original message of Andrew's is cut up badly here!

[Sorry- that's why I favor square brackets. It will probably help somewhat-
until somebody else starts doing it too...]

>[This computer doesn't seem to be set up that way. Instead of being slid
>into slots like a modern computer, its 4 panels are screwed to a back
>plate, which mounts on the door of the control cabinet. The only tag on the
>computer said "Industrial Information Controls Inc PC-LSP-08." I think they
>made the rest of the control stuff too. The only way the machine reboots is
>by turning on and off the main switch, which looks like a car door handle
>mounted on the back of the control cabinet.]

Okay. With something like this, you need to kill all the power to the
machine

[I've wired it in solid- no plug. Is it sufficient to turn of the power
with the switch, or do I need to find the capacitors and drain them?]

and use some good contact cleaner. Take apart the plugs between
boards, one at a time, and spray both the board contacts and the connector.
If the connector slides onto the edge of the circuit board, there will be
a bunch of flat copper, tin, or gold foil contacts printed near the edge.
The connector has metal springs that slide over these flats to make the
contact. You can wipe off these flats with a pencil eraser and get them
shiny again. If the connector slides onto pins you can do some cleaning of
the pins with long narrow strips of paper. Run a strip around each pin
like a bootblack might his polishing cloth.

[This sounds like a good idea, thanks, I'll try it.]

They've probably changed names since then. I'll see if I can find any more
info.

Industrial Information Controls Inc
14627 Martin Drive
Eden Prarie, MN 55244
It's on the plate block of your drawings.

[I tried to track them down, but no luck. They've either moved, folded,
changed names, or been absorbed by some other company.]

I saw a mechanical indexer a few years back. It had a plunger on top that
would move the chuck. You just programmed a move to it and plunge and the
chuck turned the distance you set. I thought it was cleaver, some others
thought it a waste of machine time. You could do something similar with a
cheapo, a little ratched plunger and a brake. Or electric with a switch.

Computer controlled indexers are more expensive. A nearby shop bought a
rock-solid indexer with control that would step in arc minutes for 12k.

[Yowza!]

There are some older Yuassa indexers that sold new for 2-3k that would do a
nice job of small steps and would easily fit on your machine. You could
make your own with a stepper motor like you said and use the emc to run it
but I'd have to think about triggering it.

Ray

[If anybody comes across one of these in good used condition for cheap, let
me know. It shouldn't be too hard to insert a command at the end of each
line, but I'm not sure how to get the indexer to read it. A kludge might be
to use a electro/mechanical indexer as described above, and trigger it with
a switch activated when the milling table reached the end of its stroke.]

Message: 11
Date: Fri, 15 Oct 1999 20:23:21 +0200
From: "Arne Chr. Jorgensen" <instel@...>
Subject: Current loop

Andrew:
-------

Well, I will give you a short explanation on the TTY stuff:

[Thanks- that made it a lot clearer. I'm not quoting the whole thing, in
the interest of brevity, but I do still have a few questions. 1) Which
functions are controlled by these 4-20 mA circuits? Is it just the feedback
from the tach and encoders, or does this also run the keyboard-panel stuff,
like the "handwheel", jog buttons, and tape reading? 2) The machine has a
26-pin ribbon connector (among a bundle of single wires) running from the
keyboard control panel (hung off the side of the machine) which goes
directly to the control computer (not to any opto isolater). Is this all 20
mA? Is it likely to be the input from the tape reader, and how can I tell
for sure? 3) If this changes to a different system when the RS232 plug is
rotated, should I be very careful not to do that, or does it not matter? I
don't want to burn anything up quite yet...) ]

(Snip)

If you set up a the communication adapter as I told you, then the
opto isolator is noting but a LED in one end, and a photo sensor
on the other side of the light path. The receiving circuit will
sense the light from this internal LED, and output the signal.

Let us wire two computers together, and let them communicate over
this current loop. I call them computer A and B.

The A computer will send data to B.
--------------------------
Internal on the adapter card, there is a resistor between the 5V
rail and pin 9 on the DB25 connector.

You wire this pin, to pin. 18 on B computer. Then another wire
from B's pin 25, and back to A's pin 11.

Internal on A, is a TTL circuit that can drive this pin 11 to
ground, via an internal resistor of 100 Ohm.
Internal on B, is a LED diode in the opto isolator.

So here is from A - 5v - 50 Ohm -(pin 9) -> your cable -> B's (pin
18) LED anode to cathode (pin 25) -> your other cable -> A's (pin
11) - through a 100 Ohm resistor - > TTL port pin.

When A's internal TTL port goes low ( ground ) a current of approx.
20 mA will go through the LED on computer B. The opto sensor on B
will read this. This LED will then transmit the data of zeroes and
ones

An identical path can be connected on computer B, - that is two
more wires, and you have a the two devices talk to each other.

Most people don't know about this other way to use the COM1 or COM2
port, because you often have to change the mode on the adapter card
inside the computer.

[Are you saying that all computers have opto isolaters built into their I/O
cards, and that this is the way parallel ports are supposed to work? (I
never knew this). Or is there a special modification one must make, besides
resetting jumpers on a standard adapter (or is there a way to change the
mode in software?) I'd like to try feeding g-code information to my machine
through the existing tape-drive connection, if only to see what happens. ]

Andrew Werby


Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
http://unitedartworks.com