LAN extensions for instrumentation

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Logo of the LXI consortium

LAN eXtensions for Instrumentation ( LXI ) is an open specification for networking measuring instruments and systems via Ethernet (LAN). The LXI organization currently includes around 50 measuring device manufacturers. With the help of the widespread LAN technology, large and locally distributed test and measurement systems can be easily networked with one another. Access to the entire test system via a company network is also possible.

In addition to the required LAN interface, every LXI measuring device contains a special web interface with server and browser that provides the actual functionality.

Classes

Large and complex measurement and test sequences require synchronization of the measurement devices involved, so that, for example, signal power is only measured when the signal is actually present. For such applications, measuring devices have a so-called trigger input, via which a start signal is fed. If the measuring device receives this signal, it starts with the previously set measurement.

Due to the communication via Ethernet, triggering is only possible under special conditions. For this reason, three classes were originally defined that describe the requirements for the precision of the timing of a device.

Class C

Only the measurement and control data are transferred via the LAN. Triggering takes place on the measuring device via independent inputs and outputs.

class B

In the case of class B devices, the measuring devices are synchronized using the IEEE  1588 Precision Time Protocol (PTP) . This standard enables the synchronization of the entire measuring system connected to LXI. The individual clocks can have different resolutions, accuracies and stabilities. Synchronization with IEEE 1588 PTP enables time accuracies in the ns range to be achieved.

Class a

In class A, the IEEE 1588 PTP synchronization is expanded to include the Wired Trigger Bus (WTB). This allows very time-critical measurement setups to be implemented, provided they are spatially compact.

Version status LXI 1.4

In this version, the "3-class system" was dissolved. Entry class C became the basic standard. The requirements that had been added to classes B and A up to that point were broken down into individual requirements that can each be achieved individually. The class C + (corresponding to class C, as well as implementation of the trigger bus, which is required in class A, but does not meet the requirements of class B), which has been haunted by the press again and again until then, is made possible.

history

  • Foundation of the LXI consortium in September 2004
  • LXI 1.0, released September 2005
  • Certification of the first LXI-compliant measuring devices in December 2005
  • LXI 1.1 released in August 2006
  • LXI 1.2, released October 2007
  • LXI 1.2.01, released November 2007
  • LXI 1.3, released October 2008
  • LXI 1.4, released May 2011
  • LXI 1.5, released November 2016
  • LXI 2.0, in preparation

See also

Web links