Signals on the Bus Cable
All modules are connected with a 10-pin ribbon cable that runs below the modules. Each module is plugged onto this bus cable with a 10-pin connector.
A master module is usually the source for this ribbon, supplying both power and control signals (derived from midi).
The master module has 2 connectors for 2 separate ribbons.
The top 4 pins are used for power. The remaining 6 pins are all derived from MIDI by the master module.
|supply voltage; red stripe on the ribbon cable||+5V|||||+5V||supply voltage; red stripe on the ribbon cable|
|ground signal||GND|||||GND||ground signal|
|pitch CV 1V/oct (label: BUS CV)||CV|||||GATE||gate (0 or 5V) (label: BUS GATE)|
|start of clock used for reset (label: B.START)||START|||||CLOCK||clock pulse (24ppqn?) (label: B.CLOCK)|
|CC #20 (label: BUS CTRL)||CTRL|||||STOP||stop clock signal (label: B.STOP)|
NOTE: the control signals should be considered as output only, since they are pushed by the master module.
NOTE: All modules use the same 5V / Ground rail so modules need to take care not to induce a ripple voltage which can introduce noise.
How to make your own ribbon cable
You can of course make your own, it's really nothing special. Here is a general guide on how to make those: https://startingelectronics.org/articles/IDC-ribbon-cable/