Re: Using a printer switch to switch between controllers?

Hi Nick,
Keep the parallel port extension from the PC to the switch box, and
from the switch box to the drive as short as possible. I would
recommend getting a new printer switch box, so you know all the
contacts are nice and clean (or make sure an old one has clean
contacts inside). Cyberguys has a 2-to-1 box for $4.23 (plus
shipping).

The gender of all three connectors on a switch box is often the
same, so you may either need a gender mender, or a cable going from
the PC to the switch box that accomidates the required connection.

As someone mentioned in a different post, switch when the drive is
off. This is simply to keep erronious signals from getting to the
drive/motor combination.

Switching the signals as mentioned above is the better way to do
things. Switching motor leads is not a good idea (I consider it a
very bad idea), as motor/drive setup/re-setup time is -*THE*- time
when things can go wrong (i.e. forgetting to power down before motor
disconnects).

The Xylotex drive has RC filters and logic level buffers that can
accept quite low voltages on the port and still work fine (made
for 'green' PC parallel ports). I'm not sure what the Taig
controller wants.

The Xylotex requires active high (+) STEP pulses with a typical
duration set to 2uS. The DIR line needs to be stable 200nS before
and after the rising edge of STEP. The drives ship in 1/8th step
mode. Thus all of your parameters and setups for the Xylotex and
Taig Box will differ, and you need to make sure you start the PC with
the proper setup for the particular drive selected by the switch box.

Jeff
http://www.xylotex.com


--- In CAD_CAM_EDM_DRO@yahoogroups.com, Nicholas Carter and Felice
Luftschein <felice@...> wrote:

>
> I am running out of space in my tiny shop and rather than

dedicating a

> computer for each small CNC machine I'd like to have two

controllers

> hooked up to one computer through a printer switch.
> These are small controllers, Taig and Xylotex and no, I won't be

using

> more than one at a time...
> Are there any issues I should be aware of like voltage/current

drop,

> unreliability, total destruction of the control, etc? Anyone doing

this?

> The printer switch I have is old - I know some changes have been

made in

> communication between printers and computers in the last, um, 6 or

8

> years, are there big diferences in switches?
>
> TIA,
> Nick
> --
> felice@... is Nicholas Carter and Felice Luftschein. See our
> homepage at www.cartertools.com/nfhome.html
>