Msg: 1144 *Conference*

12-20-91 23:12:42

From: IRVING MOY

To : RICHARD HANSON

Subj: REPLY TO MSG #1140 (USING RS-232 & MODEM AT SAME TIME)

  OK Rick, the situation I am dealing with is as follows: I have a friend who
does animation using a commercial package on an PC clone. He films the frames
one at a time from an RGB monitor connected to the PC clone.  The problem is to
automate the filming process.  He and another animator came up with a hardware
hack that works "most" of the time.  My friend does film animation as a
business so "most of the time" is not good enough.
  The animation package on the clone can interface to commercial single frame
controllers for videotape recorders (NOT film cameras) through the clone's
RS-232 port.  He has an interesting interface to the film camera: it's a
commercially made A/D interface that runs off an RS-232 connection.  For
output, it uses relays (good for controlling the motor on the film camera) and
it has input sensors also (optoisolators, I believe).  You send this interface
a certain ASCII sequence and it turns a particular relay on/off or it checks
the status of an input sensor.
  My friend has a Model 100 and a Model 102; he uses them to help with various
production calculations and record-keeping, etc.  He got a fellow Model 100
owner to write a BASIC program to control the relay box interface.  I wrote
another BASIC program to emulate a single frame controller; i.e., I can connect
a Model 100/102 to the PC clone via RS-232, run my program and the animation
package on the clone thinks it's talking to a single frame controller.
  I bet you can see what I have in mind...... I want the same Model 100 to
control the film camera via the RS-232 controlled relay box. That means I need
another RS-232 port on that Model 100....hey, why don't I use the internal
modem to talk to the OTHER Model 100??? It's got a BASIC program to control
that relay box already!!! I'll just connect the M100's together by using
direct-connect modem cables; the M100 that's talking to the PC clone will tell
the other M100 when to shoot a frame.  Problem solved!!!!
  So I thought....  As you pointed out, the Model 100 only has one UART so I
have to keep switching back and forth between the modem an RS-232 port.  This
is not a problem since filming a frame is a serial process, not a parallel one.
The clone tells the M100 it's connected to that it has a frame to shoot; that
M100 then tells the other M100 to shoot a frame and finally, (whew!!) the other
M100 sends an ASCII sequence to the relay box to actually shoot a frame. The
bad part is that I noticed the sound of relay opening and closing every time I
sent data out the modem port by using the PRINT #...  command.  Since an
animation can consist of THOUSANDS of frames, I'm worried this little relay
will wear out and my friend won't notice until after the film is developed.
This means reshooting and that is not cheap.
  The question I have to deal with is now how to get around that 
relay....either keep it closed or keep it open.  If it's not necessary to the
process of connecting two Model 100 together, then I suppose it can wear out
without hurting the filming process.
  Sorry to go on like this, but I figured I should lay out the entire problem
so others could look at it and perhaps see a better solution or offer advice.
Thanks for your patience and help!!!