Greetings-
I've spent the last week working on the physical-hardware-to-
virtual-world-and-back-again problem, and seem to have met with
some success.
Thanks to some help from Robert and Etienne's parallel port DLL
I got the following to work today:

     I got a motion detector (electrical switch) to play
     a note on a MIDI keyboard, which sent a note-on event
     thru a standard MIDI interface into a win95 PC running pd.
     Then pd used "netsend" to pass the note number to another
     machine on our campus network, also running pd. It, in turn
     used "netreceive" to get the number. Then thanks to Etienne's
     DLL, pd was able to pass the numerical value to the parallel
     port as a binary ascii pattern. Since the port was attached
     to one of the I/O boxs we built here at MassArt, the binary
     pattern was converted into a pattern of individually
     addressable output voltages (translates into on/off switches).

This means:
  1- Any sensor-driven on/off switch we can make in the physical
     world can send information to a PC or Unix machine on the
     same network. 
  2- And also- by interpreting change-of-state information into 
     numbers that pd can send over the network, events in the 
     virtual world can switch devices off and on in the physical world.
     
A few of questions I had:
  1- Has Robert or someone written the necessary "translator function"
     that can take the data sent from a machine running pd and output
     it in a form that makes sense to your VR network protocol?
     Or is that even necessary, since pd is just opening a socket
     and sending integers, strings, floats, or whatever...?

  2- When pd is initialized with the parallel port ExTest lib, the
     pd window prints the message, "dacs died... Switching to alternate
     time source." Does anyone know what that means?

  3- With the I/O box I have here and the one at BU, we have a total
     16 switches that can be controlled by the virtual world. I have
     a Grad student working on finishing a couple more, but I don't know
     how long that will take. My question is: "Are we even close, or
     is there something that is going to need 2 dozen inputs or more?"
     There are commercial products in the $100-$200 range; I/O boards
     with many more ports, if we need to get such a thing in a hurry,
     but even then, it's not clear what will be involved in writing
     the code necessary to interface it with pd.

  4- pd has been running in a way that I can only describe as "flakey".
     (Suddenly clogging-up and not receiving midi data, having to
     do re-starts, etc...) Robert, if it seems to be relatively stable
     for you, can you tell me the configuration of the machine you're
     running it on? We're using a 450mhz AMD K-6 -but with only 64 megs
     of RAM. Maybe pd needs a lot of RAM?

I'm putting together some toys that might be fun for thursday; just to
see some interaction between physical objects and the virtual world.

Hope you are all staying cool.

-Dana Moser

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