PXI Express: extending backplanes to 6 Gbyte/s while maintaining backwards compatibility

The PXI Express specification integrates PCI Express signaling into PXI to enable new levels of performance in modular instrumentation systems. By leveraging the commercially available PCI Express industry standard, future PXI systems can benefit from both very high performance as well as high component availability at lower costs. PXI Express maintains backwards compatibility with the PXI specifications in three ways. First, software compatibility is provided inherently in the architecture, as the PCI Express software model is backwards compatible with PCI by design. Second, PXI Express defines slots that accept either a high performance module that uses PCI express for data transfers, or a module designed to the PXI specification using PCI for data transfers. Third, the PXI Express specification allows for chassis with PXI slots that do not have PCI Express signaling. This combination of software and hardware compatibility allows both customers and vendors to preserve their investments in existing systems, modules, software, and designs