Hello,
Are you talking about the trigger input to the card itself? This is one BNC input, which reads a TTL signal. Acquisitions can then be triggered on either the rising or falling edge of this signal.
As far as the BNC pin itself goes, the central pin is the positive, (signal input), pin. The ground of the BNC trigger is the metallic ring, (insulated from the central pin).
Is what you meant? Were you after more detailed information regarding the BNC triggering?
Ryan.
