A DIO domain has one Master DIO board and up to fifteen DIO Slave boards. A DIO domain is comprised of a Master and its Slave boards. The figure bellow shows two domains of DIO boards. .
Two Different DIO Domains on One PC Bus
Domains are internally synchronized and controlled via the PXI local bus. To synchronize a domain with a UUT, you need to synchronize the Master board’s Timing signals using the Master’s Timing connector.
A full domain containing sixteen DIO boards provides up to 512 UUT I/O channels (512 channels wide). Because the driver supports 16 masters, up to 16 domains of mixed types can, in principle, be supported in a PXI system. The number of master/slaves depends on the number of available free PXI slots in your system.