I attached the laptop's serial port transmit line to a Serial to parallel converter to drive a set of relays that in effect "push" the buttons of the machine. I also attached the serial ports receive line to a Parallel to Serial converter to "read" the status switchs and determine if the clamp is closed or open and things like that.
more... 10/97 I like my old Arburg. It is a joy to run and work on because it is so well made with the best materials. I moved to a place in Oregon (with my Arburg) in 1988 where there is no 3 phase power available so a friend made me a phase converter for it's 18hp motor and I re-wired the the rest of it to be happy with single phase 220V. I goofed somewhere, didn't make it happy enough and burned out part of the control which is all wire wrap IC's. It turned out that I did not have the correct schematics for the control and I could not seem to fix it, although, in many attempts to reverse engineer it I had great fun learning all about good old 70's machine automation circuits. I did locate a fellow who would fix it for about $2000.00 but then I found a way to get around the problem. The control worked great in manual mode. Only automatic mode was non-functional. Sooooo... me thinks to myself, if my laptop computer could "push" the buttons and "read" some of the switches like "mold is open" and "mold is closed", like that, and it can do it's own timing of events, wow, ... I could program it to do almost anything, and I could save the programs by name and have all kinds of stored setups, and ... count things, ... and do things the control can't do, wow. how cool? ... so with a serial-to-parallel converter and a parallel-to-serial converter (a friends company made), and a set of relays (I made) I wired my Arburg to a laptop computer's serial port with 3 wires, wrote a simple program in basic, and have everything I could ask for in machine control ... and total control and understanding of what going on, how to change it, and how to fix it, plus saved $2k, enough to buy a very cool dryer. The only thing I mold with it in the last few years is this thing here, http://home.cdsnet.net/~purple/projects/g45contr/g45_idx.htm (see photo) which is the first ever (as far as anyone knows) share-ware-hardware global distribution project on the internet which has keep me very busy since Jan 1996. A few hours ago Angus Pinkerton, wife and 2 kids left here to return to Scotland with more supplies. (you can see Angus by clicking on Pfranc-map, then the UK. So that's it. I think a great story of how anyone with an Arburg and an internet account can change the world (just a little bit). You can follow the entire story starting here; http://home.cdsnet.net/~purple/projects/g45contr/status/st0109.htm The only regret I have about my Arburg control being broken is if I were to sell the machine. I wouldn't expect the buyer to trust my modifications or appreciate how cool they are. People are that way. And if anything went wrong with it, they would have to call me... though I did document it well, I think. Anyway, I like it so much, I don't want to sell it anyway, unless I would be getting a new one!