Just an idea. But why not just built a small separate housing for the ipac, then run the cables from that to each control panel, or the the first one, then from there to the second? This may not cut down the the length, but might make it a bit easier overall.
I was thinking about this just today (wire length). So I decided to see what would happen. I took about 20 feet of wire and connected it to my ipac, and then to a button. I used notpad to test it out and it worked quite well. I didn't see any signal loss at all. But that was just 20' not 50'. I would think that the signal would still make it, but it would be off by a few milliseconds and maybe a second. Either way, I would try it with a single button and see what happens.
I am in the process of building something very similar to what's described here (and also somewhat similar to what Tiger-Heli describes on his excellent website).
I *do* have an IPAC in a separate box connected via cables to a control box that sits in the lap. Right now I am only running about 6 feet, but intend the total cable length to eventually be 16 feet or so.
I am using dsub (serial) connectors and bundled cabling (using standard serial cables). At first, I was running into ghost keyboard presses; after emailing Andy (who was very helpful as is typical), experimenting with this, and researching on the Internet, we concluded (or I, which Andy confirmed as plausible, if not likely) I was experiencing a high degree of RFI.
The RFI could be due to my location (near several radio towers) or also due to the length of bundled cables. I thought since I was using shielded cabling, I was ok.
It turns out that the problem was solved when I realized I wasn't *grounding* the shielded cable properly. Shielded cable, if you cut it in half, has the signal wires encased in foil with an uninsulated wire that runs the length. This uninsulated wire is meant for grounding the shielding. It is connected over multiple cables via the metal connection housing of the cable ends (the part that surrounds the pins).
If you are using cable cut in half, be sure to ground this wire at one end. (Andy confirmed for me that it is ok to connect this to the IPAC ground.) If you are using full cables with, say, dsub female connectors, be sure to connect the metal housing of the connector to ground...you may have to solder a wire to it for this. (Some of the old switchboxes, if you take them apart, have a wire soldered like this.)
Sorry to be so longwinded...but save yourself some pain!
b