The CMX18A is an 18-slot PXI Express mainframe with 1 system controller slot, 6 PXIe Peripheral slots, 10 PXIe hybrid slot and 1 PXIe timing slot. The ten PXI Express hybrid peripheral slots are all connected with PCIe x4 lanes. Each slot can accommodate a 3U PXI Express/CompactPCI Express/hybrid slot compatible PXI-1/CompactPCI peripheral module.
The PXIe timing slot accepts either a PXI Express module or a PXI Express system timing controller for advanced timing and synchronization. The system controller slot has configurable 4x4, 2x8 and 1x8 links, which makes it very flexible allowing all PXIe controllers to be supported per spec.
High Bandwidth
The CMX18A uses a 4-lane Gen 2 PCIe backplane to achieve unmatched data rates of up to 4 GB/s per slot and 8 GB/s system. PXI Express slots 8, 9, 11 and 12 are high bandwidth and provide connectivity to a x8 PCI Express link which allows 4 GB/s data rates. The high bandwidth allows the chassis to be used with high-speed instruments like digitizers, oscilloscopes, and signal generators.
External Clock
The CMX18A includes a pair of IN/OUT BNC connectors in the rear to bring in an external 10 MHz reference clock. When a 10 MHz clock signal is detected on the IN connector, the internal clock is phase locked to the external clock. This reference clock may also be driven by a system timing module in slot 10. System timing controllers provide a high-stability clock source and the ability to drive the PXI star and PXI Express differential star triggers. In addition timing controllers typically have the ability to import and export the PXI trigger lines on the backplane. The OUT BNC connector
provides a buffered, non-TTL version of the 10 MHz reference clock.
Advanced PCIe Switch Fabric
The CMX18A’s advanced switch fabric uses innovative methods like non-transparent bridging and partitionable switch architecture to allow slot-to-slot direct communication and true multiroot support. Slot-to-slot direct communication allows data from any slot to be read directly by another slot, without having to go through the controller and host. This allows extremely high-speed, deterministic data transfers between slots, which is very useful for example in applications that require closed loop control.
