LAN eXtensions for Instrumentation (LXI) is a standard which defines the

communication protocol A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any variation of a physical quantity. The protocol defines the rules, syntax, semantics (computer science), sem ...

s for instrumentation and

data acquisition Data acquisition is the process of sampling signals that measure real-world physical conditions and converting the resulting samples into digital numeric values that can be manipulated by a computer. Data acquisition systems, abbreviated by the ...

systems using

Ethernet Ethernet ( ) is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...

Overview

Proposed in 2005 by

Keysight Keysight Technologies, Inc. is an American company that manufactures electronics test and measurement equipment and software. The name is a blend of ''key'' and ''insight''. The company was formed as a spin-off of Agilent Technologies, which inhe ...

and VTI Instruments, the LXI standard adapts the

and

World Wide Web The World Wide Web (WWW or simply the Web) is an information system that enables Content (media), content sharing over the Internet through user-friendly ways meant to appeal to users beyond Information technology, IT specialists and hobbyis ...

standards to test and measurement applications. The standard defines how existing standards should be used in instrumentation applications to provide a consistent feel and ensure compatibility between equipment. The LXI standard does not define a mechanical format. LXI products can be modular, rack mounted, bench mounted or take any other physical form. LXI products may have no front panel or display, or they may include embedded displays and keyboards. Use of Ethernet allows instrument systems to be spread over large distances. An optional Extended Function based on IEEE 1588 Precision Timing Protocol allows instruments to communicate on a time basis, initiating events at specified times or intervals and time stamping events to indicate when these events occurred.

Interoperability and IVI

LXI devices can coexist with

devices that are not themselves LXI compliant. They can also be present in test systems which include products based on the GPIB,

VXI VME eXtensions for instrumentation bus (VXI bus) refers to standards for automated test based upon VMEbus. VXI defines additional bus lines for timing and triggering as well as mechanical requirements and standard protocols for configuration, me ...

, and PXI standards. The standard mandates that every LXI instrument must have an Interchangeable Virtual Instrument (IVI) driver. The IVI Foundation defines a standard driver

application programming interface An application programming interface (API) is a connection between computers or between computer programs. It is a type of software Interface (computing), interface, offering a service to other pieces of software. A document or standard that des ...

(API) for programmable instruments. IVI driver formats can be IVI-COM for working with COM-based development environments and IVI-C for working in traditional

programming language A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...

s for use in a .NET Framework. Most LXI instruments can be programmed with methods other than IVI, so it is not mandatory to work with an IVI driver. Developers can use other driver technologies or work directly with

SCPI The Standard Commands for Programmable Instruments (SCPI; often pronounced "skippy") defines a standard for syntax and commands to use in controlling programmable test and measurement devices, such as automatic test equipment and electronic tes ...

commands.

Standardization

The LXI Standard has three major elements: # A standardized LAN interface that provides a framework for web-based interfacing and programmatic control. The LAN interface can include wireless connectivity, as well as physically connected interfaces. The interface supports

peer-to-peer Peer-to-peer (P2P) computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the network, forming a peer-to-peer network of Node ...

operation, as well as master/slave operation. Devices can optionally support IPv6. # An optional trigger facility based on the IEEE 1588 Precision Timing Protocol that enables modules to have a sense of time, which allows modules to time stamp actions and initiate triggered events over the LAN interface. # An optional physical wired trigger system based on a Multipoint Low-Voltage Differential Signaling (M-LVDS) electrical interface that tightly synchronizes the operation of multiple LXI instruments. The specification is organized into a set of documents which describe: * The LXI Device Core Specification which contains the requirements for the LAN interface which all LXI Devices must adhere to * A set of optional Extended Functions which LXI devices can adhere to. If a device claims conformance it must have been tested under the LXI Consortium Conformance regime. As of March 2016, there are 7 Extended Functions specified ** HiSLIP **

IPv6 Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communication protocol, communications protocol that provides an identification and location system for computers on networks and routes traffic ...

** LXI Wired Trigger Bus ** LXI Event Messaging ** LXI Clock Synchronization (based on IEEE1588) ** LXI Time Stamped Data ** LXI Event Log

Specification History

In 2005, the LXI Consortium released Version 1.0 of the LXI Standard. Version 1.1 followed with minor corrections and clarifications. In 2007, the Consortium adopted Version 1.2; its major focus was discovery mechanisms. Specifically, LXI 1.2 included enhancements to support mDNS discovery of LXI devices. Version 1.3 incorporates the 2008 version of IEEE 1588 for synchronizing time among instruments. As of November 2016, the standard is at Revision 1.5.

Conformance testing

The LXI Consortium requires LXI Devices to go through standard testing. To support this compliance regime an LXI Test Suite is available. After a vendor joins the LXI Consortium they can gain access to the Consortium's Conformance Test Suite software, which they can use as a pre-test before submitting the product to the Consortium for compliance testing. Once a product is ready to submit, a vendor can choose to have their product tested at a PlugFest or an approved test house. A Technical Justification route allows vendors to certify compliance of derivative products by submitting test results to the Consortium to show that the device has been tested on the LXI Test Suite. The consortium provides guidance on when the Technical Justification route can be used and when a new formal test is required.

References

* Interchangeable Virtual Instrument (IVI) Foundation website

External links

* {{Official website, http://www.lxistandard.org Networking standards Electronic test equipment