RE: [CAD_CAM_EDM_DRO] Re: 5V+ Supply for Gecko? Still confused!

Abby:

The optos are triggered by "negative voltage" on the step/dir pins only as
referenced to the +5V. The signal they get will be the "ground" of the +5V
supply from the PC(or from the breakout board, if you are using one with a
separate supply). The parallel port pins should be set up for "active low",
which, yes, means that they go to ground when they are on. The pins will
alternate between their OFF state(at +5V or close to it) and their ON
state(at ground(0V) or close to it).

There is no pin on the paralle port that supplies a +5V supply, although I
suppose if you didn't need a lot of current, and if your CAM software
permits it, you could set a pin to be "high" all the time, and use this as
the +5V for the Geckos. I am not sure if a standard parallel port will be
able to supply enough current to power a Gecko(or multiple Geckos, as I
guess you have more than one axis.

Your best bet, I think, will be to do what I did, and use the supply in the
old PC case, that you are building your controller in. You can use the +5V
from that supply to the Geckos, and the only other thing you will have to do
is connect the Ground(0V) of that supply to the Ground(0V) of the PC's
supply. There ARE ground pins on the parallel port.

Andy Wander
Verrex Corporation


-----Original Message-----
From: Abby Katt [mailto:cnc@...]
Sent: Wednesday, September 22, 2004 12:25 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: 5V+ Supply for Gecko? Still confused!

Hmm.. myabe I'm having a brainworm day, but I just don't get this
still.

Okay, since we've established that the gecko has it's own internal
bus which is powered from the 18-80V motor supply, and we know this
powers the encoders....

The Step/Dir pins and the 5V+ pin of the gecko make up two opto-
coupled LED's emitters. From looking at the circuit diagram, it looks
like the step-dir pins are triggered by negative voltage on the
parallel port. Am I correct in assuming that when the parallel port
pulses, it is negative?

Now surely, if this is going to be negative, then there wil be a
positive pin, or two in the parallel port, as I don't see
lineprinters needing the PC power supply connected. All we need to do
is light up two opto-isolator LED's from the parallel port - surely
there is going to be enough power/connections for that?

Sorry if this is painful.... there just seems to be something I'm not
getting here.