cleat,
According to the product page for the PCI-6515 board, the board has 64 total lines, 32 inputs (sink or source) and 32 outputs (sink only). So basically, the lines are not bi-direction on this board, the inputs and outputs are separated. Please refer to the
PCI-6515 Product Page for additional information about the board. Hope this helps clear up the confusion, have a good day cleat!
Sincerely,
RossC