What is LXI?
It is an acronym for LAN eXtensions for Instrumentation. LXI builds on industry standards, particularly those supported by the IEEE, to provide a standardized method controlling instruments and other devices through a LAN interface and at the same time provide a capability similar to or exceeding the IEEE488 standard.
Where can I get copies of the LXI standard?
A publicly available version is available on the LXI web site www.lxistandard.org . Copies of working documents are available by joining the LXI Consortium. Joining the Consortium allows companies to actively participate in the creation and the promotion of the standard and gives access to other companies experience in implementing the standard.
Who is supporting LXI?
Virtually all the leading companies in Test and Measurement are supporting the LXI standard. A membership list can be obtained form the LXI Consortium web site.
What is different between LAN instruments and LXI?
There are instruments available that have LAN interfaces that are not LXI compliant. They behave in proprietary ways and all the legacy LAN instruments tested initially failed some aspect the LXI specification, highlighting the advantages of adopting an industry standard.
Does LXI compete with PXI?
Only to a very limited extent. The architectures are quite different and consequently each will find their own market place where they offer the best solution.
How does the speed of LXI and PXI compare?
To a great extent this is not a useful question. In PXI modules generally transfer data to a PC for analysis, the architecture requires the transfer to be made quickly in order for the system emulate traditional instruments. In LXI most instruments will internally process data and simply supply a result, so the amount of traffic is much lower. If speed is an important criteria it should be judged not on bus speed but on the speed of the overall system when it performs the required task.
What happens if I disconnect an LXI device or turn it off?
No a lot. The LAN connection has been specified to ensure that just like modern IT products the LXI device will recover from the event and will not cause the LAN system to misbehave.
Can I use wireless connectivity?
Wireless links can be included in the network, but at present the standard does not support a direct wireless connection to an LXI device.
How does LXI support triggers?
LXI has a consistent definition of triggers based on an 8 channel model. Triggers can be generated over the LAN interface, the web interface, can be timed events based on IEEE1588 or use the wired trigger bus.
What is IEEE1588?
IEEE1588 defines a method of synchronising time, in this case over a LAN interface. A system supporting IEEE1588 has a common sense of time that can be used to define (in time) when an action (trigger) needs to occur or when an event occurs (time stamp). The time stamp can be used to align data in several devices. The operation of IEEE1588 on Class A and B devices is transparent to the user once it has been set up.
What are the LXI Classes?
The most basic class of LXI device is Class C which supports the physical, programmatic, LAN and web parts of the standard. Class B devices additionally support IEEE1588 and the triggering model, Class A devices additionally support the wired trigger bus.
What is the wired trigger bus?
It is a cable based link using standard connectors between Class A LXI devices that provides 8 channels of triggering. The physical link uses Multi-drop LVDS signalling to provide a highly deterministic method of exchanging hardware triggers between devices.
Are there security issues with LXI?
There could be but these have to be addressed in the same way as other IT products that exist on LAN´s. In most cases corporate IT policy will encourage test systems to use their own LAN with external connectivity controlled in accordance with modern security practice.