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!!!