Associate Engineer-Marketing,
Using just those 3 PCI slots you're not going to be able to get the 128 analog output channels. You will probably want to go either the MXI-3 (PCI bus extender) to a PXI chassis or E Series DAQ card to a SCXI chassis for such a high channel count system. Which analog output cards and which digital I/O cards you will want depends on your application. You will have to decide whether you will need static or dynamic analog output as well as whether you need clocked digital I/O or not. I highly recommend contacting our internal sales department at 1-800-433-3488. They are great at helping specify systems.
Ames
Applications Engineering
National Instruments