8200KA1 - pc board, 28v, with 1 incand. lamp with jumper on JW1, hall button only
8200KA2 - pc board, 28v, with 1 incand. lamp without jumper on JW1, car button only
8200KA3 - pc board with 1 orange LED with jumper, hall button only
8200KA4 - pc board with 1 orange LED w/o jumper, car button only
Important note: The KA1 and KA2 are identical except for the JW1 jumper. Likewise, the KA3 and KA4 are identical except for the jumper. If you install a KA1 or KA3 (with jumper J1) in the car it can damage the microprocessor. If you install a KA2 or KA4 (no jumper), I think the light will not work. In my experience, JW2 is always present on all of these Otis buttons.
By the way, Mathis Electronics has a replacement board that can replace all 4 of these boards.
By the time OTIS released the E311, everything went serial connection to the ring car boards and no more independent group controller since each RCB can become group dispatcher. Other thing done which was clever was using the switchover module so you have full power redundancy in the hall power. It's still done this way and is a very good design in my opinion
they didn't use serial for hall buttons on any these. The only serial comm used on the older hydros was duplex communication between COP processors on two car groups on some versions of that vintage.
sorry. it was just too obvious. i couldnt help myself.