Keysight Application Note 5991-0384EN | PXI Interoperability-How to Achieve Multi-Vendor Interoperability in

Application Note 5991-0384EN Keysight Technologies // PXI Interoperability-How to Achieve Multi-Vendor Interoperability in PXI Systems.

Introduction to PXI interoperability
Test system developers generally require a large variety of components to meet system needs, and at times they are sourced from different suppliers. The system developer must have confidence that these components will work well together. Mechanical, electrical and software aspects need to be compatible to ensure successful system operation. That is one of the primary goals of standard organizations. If standards are carefully written, the resulting specification will promote compatibility between products and suppliers. In the case of PXI instruments there are multiple standards organizations that come into play. These organizations define PCI bus connectivity, chassis and timing synchronization attributes.

This application note starts with a detailed look at PXI specifications and discusses its impact on interoperability. It then discusses PXI hardware and how to select modules, chassis and controllers to ensure compatibility. PXI software, including tools such as Keysight Command Expert (KCE) and National Instruments Measurement & Automation Explorer (NI-MAX), are also discussed because software plays a large role in the overall compatibility of system components. With the goal of a smooth implementation of PXI multi-vendor based solutions, hints and tips are included throughout this note.

PCI communications
PCI bus electrical and signaling attributes are developed and managed by the PCI Special Interest Group (PCI-SIG). PCI and PCIe® electrical bus structures used in PXI are based on the Personal Computer PCI bus and common chipset and signaling methods are used. Since the PCI bus is ubiquitous worldwide, a high level of interoperability is assured by the millions of engineering hours invested over the last two decades. PXI leverages these investments resulting in robust connectivity between modules and chassis and an easy to use solution.

The engineering investments made in PCI technologies have resulted in a robust boot and messaging process. At PC boot time the PC BIOS discovers PCI hardware on the bus (including PXI modules) and the operating system will assign resources including memory and interrupt. This process is known as enumeration.

Mechanical and electrical compatibility
Upon its initial introduction 1992 the PCI bus was recognized as being a robust high speed computer interface. It performed very well in standard business applications, and it soon became apparent it also would work well in industrial applications. The PCI Industrial Computer Manufacturers Group (PICMG) leveraged the PCI bus capabilities, and in 1997 it introduced a specification for an industrial grade enclosure known as CompactPCI® (cPCI). Compact PCI was a very good mechanical platform to build from and was quickly adopted in industrial applications. The mechanical slot spacing, connector placement and pin-outs are all defined as part of the cPCI specification. Standard mechanical dimensional constraints and strict tolerances allowed smooth insertion of modules into chassis using common installation levers. These attributes combined with standard connector definitions and pin-outs allow various suppliers to begin sourcing interchangeable cPCI solutions. However, cPCI had no provisions for timing and synchronization features necessary in instrumentation applications. This is where the PXI stepped in and provided instrumentation specific features.