The commutator is a 12-channel, passive slip-ring unit from Moog (SRA-73683-12; datasheet; there is a also a similar one called the AC6200-12 but this has more friction).
For two Amplipex headstages, we are only using channels 1-9; these numbers refer to the numbers on the commutator in the schematic below (NOT to numbers on the D-sub pins):
(pdf of above diagram, which came from Amplipex)
The corresponding wire colors on the commutator are:
10 (not used) red
11 (not used) grey
12 (not used) yellow
Each D-sub connector is labeled either “1” (commutator data channels 1 and 2, purple and white/brown) or “2” (commutator data channels 3 and 4, blue and white).
On the Omnetics/headstage side, as can be seen in the schematic, the two connectors have shared inputs. To accomplish this, 5 wires (scavenged from Cat5e ethernet cable) connect the relevant pins from one connector to the next. The colors for this are:
|channel number||color on commutator wire||color on “bridge” wire between connectors|
This has my original (messy) working notes on this when I was building it (MvdM).