PREFACE
5
Preface
The PXI concept
VXI and GPIB systems meet the specific needs of instrumentation users but are often too
large and expensive for mainstream applications. PC-based instrumentation may cost less but
cannot meet the environmental and operational requirements of many systems.
PXI (PCI Extensions for Instrumentation) is based on CompactPCI, itself based on the PCI
standard. PCI was designed for desktop machines but CompactPCI was designed for
industrial applications, and features a rugged Eurocard format with easy insertion and
removal. PXI adds to the CompactPCI specification by defining system-level specifications
for timing, synchronization, cooling, environmental testing, and software. While PXI extends
CompactPCI, it also maintains complete interoperability so that you can use any CompactPCI-
compliant product in a PXI system and vice versa. PXI also makes use of Windows software,
VXI timing and triggering, and VXIplug&play instrument drivers to provide powerful and
affordable systems.
PXI Express now integrates PCI Express into PXI, providing up to 6 Gbyte/s backplane
bandwidth and up to 2 Gbyte/s slot bandwidth. PXI Express maintains backwards
compatibility with PXI, providing software compatibility and hardware compatibility with
hybrid slots and hybrid systems.
Hybrid slot compatibility
PXI chassis that provide hybrid slots can accept both PXI Express modules and hybrid-
compatible PXI modules. Hybrid-compatible PXI modules have a ‘missing’ section of
connector (see Fig. 1), which allows them to be inserted into both hybrid slots and standard
PXI-1 slots.
Because of the reduced connectivity of Aeroflex hybrid-compatible PXI modules, the PXI
parallel local bus LBL[0]–[12] disappears, to be replaced by the serial connection LBL[6],
which is typically used to provide list addresses to a 3010 Series RF Synthesizer.
