So for ACRIS, I designed a board that would take serial over USB and convert it to RS485 to send to all of the instruments.
Unfortunately, as it turns out, I made a crapload of mistakes on that board and my first attempt at soldering it did not turn out so well. I fixed the mistakes on the board (the worst being that the USB connector was actually freaking backwards), but I then began thinking a little more carefully about what I was trying to do.
It occured to me that the best way to design a USB -> RS485 converter would be to make it an actual dongle, like a flash drive or wireless dongle. The result is 2 inches long by .6 inches wide and has spots for 2 RJ-45 ports. It also uses the TXDEN signal to determine whether to send or receive data instead of just always placing the RS485 chip in transmit mode.
I’ll be sending an array of these out for ordering soon. I have to replace a few parts from the other board I designed, but other than that, it’s roughly the same as the previous ports.
One of my friends, Marcel, is a fantastic mechanical engineer. Perhaps he’ll be able to give me some guidance on building enclosures for these boards.