Re: PMDX-122 Bi-Directional breakout board, new product

Dave,

The USB connector is used for 5V power only. When powering the PMDX-
122 in this manner it must be plugged into a Host port or a powered
Hub. Passive hubs should not be used to feed power to the PMDX-122.
The USB port is one of several possible methods of powering the PMDX-
122. It will also accept low voltage AC or DC via either a 2.1 mm
coaxial plug (think wall-wart transformer) or via one of the terminal
strips.

The 8 data port pins (pins 2-9) can be either inputs or outputs, but
must all be used in the same manner. This is a limitation of the
printer port control hardware in the PC so no provision was made to
split the port on the PMDX-122. When the data port is configured for
inputs, you will have 13 inputs and 4 outputs.

There is a jumper on the PMDX-122 that sets the direction mode. It
allows input, output, and dynamic modes. The dynamic mode uses the
status output from pin 17 to control the direction of the data bits.

On the PC side the direction is controlled by bit 5 of the status
output port. When it is written as a ZERO, data is output to the
printer port. When it is written as a ONE, data can be input to the
PC. The output data is latched and will not be lost when the port is
switched to input mode. Switching back to output mode will restore
the last data written to the data pins.

The data port pins of the PMDX-122 are 5 volt logic level signals and
will drive up to 16 mA in output mode. There are pull-up resistors on
board so that the input mode can accept simple switch contact
closures to ground without needing additional external components.
The same is true for devices with open-collector outputs driving the
inputs. The pull-ups are always present, but the inputs still only
require 1.6 mA current to drive the inputs. This allows almost all 5
volt logic level devices (totem-pole outputs or open collector) to be
able to drive the inputs.

Each bit of the data port has an LED indicator. These function in
both output and input modes.

The PMDX-122 will also supply enough 5 volt power to allow direct
connection of encoders such as those sold US Digital without having
an additional power source for the encoders.

The complete PMDX-122 manual is available for download from our web
site. http://www.pmdx.com

Regards,
Steve Stallings
www.pmdx.com


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@y...> wrote:

>
> Hi Steve,
>
> Is the USB connector for 5V power ? or some other use ?
>
> Also, can you elaborate a little on the bi-directional data-port
> pins ?
>
> Which pins ? how many ? do they have to be addressed as a bank or
> can they be set indivudually ?
>
>
>
> Dave
>
>
>
>
> > PMDX has upgraded its PMDX-121 buffered
> > breakout board. It is now called the
> > PMDX-122 and supports bi-directional
> > usage of the data port pins. Added
> > features include:
> >
> > Usage of data port as output or input
> > with direction control by jumper or
> > one of the status output bits.
>
> <snip>
>
> > http://www.pmdx.com/PMDX-122/index.html
> >
> > These units are available now from stock.
> >
> > They have logic level inputs and enough
> > +5 volts aux. power out for running
> > encoders such as the US Digital ones.
> >
> > Manual is preliminary, but all the functions
> > and jumpers are documented. More examples
> > of wiring encoders and using multiple
> > boards will be added soon.
> >
> > Cheers,
> > Steve Stallings
> > www.PMDX.com