No clue.
Two 10 pin phoenix-style terminal blocks, marked COM A (left) and COM B (right). The pinouts are very strange. The first 8 pins of COMA all run to the pad marked A+ on the RS485 module. The first 8 pins of the COMB block all short to the pad marked B- on the RS485 module. The last two pins on each module are also the same - pin 9 goes to the GNSS PPS pin, and pin 10 goes to the ground pin on the output side of the RS485 module (NOT the board ground!).
I think the idea is that you could run this thing to eight different systems over RS485?
Serial data is sent over this interface at 19200 baud every ten seconds. The data looks like this:
:\xB6\x16\x01\0\x17\x17\x03\x1E\x0B\x07&\x17\0\x11]\x01j\xD7N\0\x1A\xC0\0\x9B\xC5W\x94_ :\xB6\x16\x01\0\x17\x17\x03\x1E\x0B\x071\x17\0\x11]\x01j\xD5N\0\x1A\xC0\0\x9B\xC4W\x9A\x08 :\xB6\x16\x01\0\x17\x17\x03\x1E\x0B\x07;\x17\0\x11]\x01j\xD7N\0\x1A\xC0\0\x9B\xBFW\xAD\xB5 :\xB6\x16\x01\0\x17\x17\x03\x1E\x0B\x08 \x17\0\x11]\x01j\xD4N\0\x1A\xC0\0\x9B\xBDW\xBB\0 :\xB6\x16\x01\0\x17\x17\x03\x1E\x0B\x08\x13\x18\0\x11]\x01j\xD3N\0\x1A\xC0\0\x9B\xC1W$\xC2 :\xB6\x16\x01\0\x17\x17\x03\x1E\x0B\x08\x1D\x17\0\x11]\x01j\xD2N\0\x1A\xC0\0\x9B\xC2W$\x04
COMA
COMB