I’m not sure what “outboard” means in this case.
I’m looking at the schematic diagram now, and I don’t see anything that is inconsistent with the actual circuit board. If you think that there is, please specify exactly what diagram you are looking at, what it is that you are seeing, and how that is inconsistent with the hardware.
I don’t think that the ground pins are labeled with “+” sign– where are you seeing this? Is this on the schematic or the circuit board?
As it shows on the schematic, each of the relevant I/O connectors (with signals B1, B0, B2, B3) is arranged as three pins. Ground (labeled “GND”, not “+”), 5 V (the middle pin), and the signal line. If you look at your AxiDraw, the 3-pin connector that is there has three wires that are black (GND), red (middle, +5 V), and white (signal). The other 3-pin connectors are wired up exactly the same way: Ground towards the edge of the board, 5 V power in the middle, and signal furthest from the edge of the board. If you look closely at the circuit board itself, you may (depending on exactly how the screw heads and connectors line up) also be able to see some very small labels there, labeling the vertical row on the edge as “GND”, the middle row as 5V, and the inner pins as B1, B0, B2, B3.
As far as how to hook up your relay, you should follow the manufacturer’s recommendation. There is probably a reason that they specify one terminal as positive.
