Being totally immersed in work earlier this evening, I completely neglected to tune in the Lurch and Chimpy Show. Had I thought about it, I would have... um... not tuned it in. It's bad enough inviting politicians into the living room on a regular little TV set, but larger than life on the projection TV just doesn't bear thinking about.
I'd watch some Rocky and Bullwinkle instead, but there's still work to be done.
Here's a bit of the work:
Well, looky here: this RS-422 interface appears to be working after all. Turns out the weirdness I'd been seeing was the result of having plugged in the extension cable for the relays off by one position. Plugging it in right gets (as far as I've tested) correct behavior. From top to bottom: transmit data, line (+ and -), receive data. (This is, of course, with a loopback connector in place.)
Oh, and here's the new board, just built this morning (detached from the main board for a better view):
Now that I've seen it working, it's time to fix a problem or two with the PCB layout, generate fresh Gerbers, and order a couple of revised boards before bedtime (being as how the deadline for the board order is 8 AM).