Hi, I bought the 6542 i/o card to record some date from an self made board.i send the clock out to this board by the clock SMB connector, than the board receive the clock and send the data to the i/o card. Therefore i use a cable which is provided by NI. The problem is, that I get an high noise which influence the self made board. If I unplug this cable the noise is gone.Maybe I need an resistor for the impedance on the side of the I/o card..or??Thanks