I'm trying to implement a 16 bit bi-directional bus using compact RIO modules. However I'm not sure if this is doable without an external tri-state buffer. I need 16 lines input and 16 lines output, with some handshaking. The device I'm interfacing to has a bi-directional 16 bit bus.
1. 9403 specifies 18us line direction change time, which is too slow for my application. 9401 doesn't specify a direction change time, but meets the speed spec for line transitions (100ns). The 9401 example in LabVIEW shows changing direction, however it has to wait for the direction change status to become ready, which might imply it's slow.
2. Is there a tri-state mode for the I/O lines on the 9401?
3. Am I better off adding an external tri-state buffer and dispensing with trying to change I/O direction on the fly? This would double the number of I/O lines on the cRIO side (2X 16 bit busses rather than 1X), but I can deal with that.
Thanks!
