You can use the two BNC terminals on each cDAQ to input or output timing signals for all task types. That means you can share a clock and a trigger from one of the chassis to the other, so you can synchronize any tasks that would use those shared timing signals.
* Note that the chassis PFI lines support a maximum input or output frequency of 1 MHz, so you will not be able to share a timebase or a clock with higher than 1 MHz frequency between the chassis through those terminals. In order to share higher frequency timing signals, you would need to use module PFI lines (on a DIO module installed in the chassis) or the NI 9469 chassis synchronization module.
