Hamamatsu Photonics c2400 Instruction Manual page 15

OUT 1 unless the CCU is configured for Operational Video Output,
in which case, this terminal outputs operational video signals in-
stead of composite signals.
0 H D
This terminal normally outputs HD (Horizontal Drive) signal. When
the M2505 EXTERNAL SYNC option is installed this terminal be-
comes an HD signal input.
0 V D
This terminal normally outputs VD (Vertical Drive) signal. When
the M2505 EXTERNAL SYNC option is installed this terminal be-
comes a VD signal input.
6 GND
This is the frame ground of the CCU. Utilize this terminal to provide
a "common" ground to other equipment being used.
C O LINE
This cable supplies power to the CCU.