this is a qoute from the data sheets of the camera:
in VISCA, up to seven peripheral devices like the camera can be connected to one controller using communication conforming to the RS-232C standard.

pin assignment:
pin 1 (RxD - CMOS 5V (low:max 0.8V, high:min 2.0V) Read data.
pin 2 (TxD - CMOS 5V (low:max 0.1V, high:min 4,4V) Send data.
pin 3 GND for RxD & TxD.

when i read this i asume that this is the RS-232 protocol. so i should not know why this CAN'T be the RS-232 protocol.