Well just to complicate things further, I checked the wiring to DB9s on the back of the display. Turns out that there are wired pins that connect to unwired pins on the other side of the connector in both directions! In other words, they connect to air. From what I can tell, there are only 4 pins truly in use. So this is the most basic TTL with V+, Ground, A, and B. That makes it easier to deal with. I will make an adapter for the Electronica scale based on this. Looks like I will only need 4 wires to the correct pins and the + and Ground are easy to identify. Even if A and B are backwards that will just change the direction of the scale.