Solution
To connect multiple USRP devices to a single MXI-express host controller, use a
CPS-8910. The CPS‑8910 is MXI-Express switch designed for large multiple-input, multiple output (MIMO) expansion configurations and system control on the PXI platform or Software-Defined Radio devices. The CPS‑8910 provides two MXI Express upstream ports and eight downstream ports for system expansion.
When connecting to the CPS-8910, you must connect one of the two upstream ports to a host controller. The two options for upstream ports are MXI-Express Gen2 x8 (3.2 GB/s) port and MXI-Express Gen1 x4 (832 MB/s) port.
Each port has a different bandwidth limit, which must be considered when deciding which interface to use. This bandwidth is split across all USRPs connected to the CPS-8910. For instance, if you have 8 USRP devices streaming 25 MS/s of IQ data to the host system, it will generate 800 MB/s worth of data (8 USRP device * 25 MS/s * 4 Bytes/sample = 800 MB/s) and we can use the MXI-Express Gen1 x4 port.
Additionally, a different host controller part is required for each port. The MXI-Express Gen1 x4 port requires a PCIe - MXI Express Interface Kit (PN 783487-01) for a PC, an Express Card - MXI Express Interface (PN 783489-01) for a Laptop, or a PXIe - MXI Express Interface (PN 783488-01) for a PXI chassis. The MXI-Express Gen2 x8 port requires PCIe-8381, x8 Gen2 MXI-Express for a PC, or PXIe-8384, x8 Gen2 MXI-Express for PXI chassis; there is no option for MXI-Express Gen2 x8 for Laptops.
The downstream links connect to the USRP device through MXI-Express Gen1 x4 port.