XPressNet is a Command Bus used by Atlas, Lenz, Hornby, OpenDCC (DIY), Paco Canada (DIY), ZTC Controls, Viessmann, and Roco. It was developed by Lenz. The XPressNet specification (available from the Lenz website) specifies the electrical communications standards and command set needed for devices to communicate with the command station. While the command stations support the same commands over the XPressNet connection, they do not all use the same connectors. It may be necessary to build an adapter to plug a device into a command station from another manufacturer.
The hardware for XpressNET is based on the industry standard RS-485 protocol which is widely used in industrial control applications. Out software protocol is in the public domain and a complete description including the full protocol suite is published on our WWW site. This allows other companies to develop products to the same specifications.
The XPressNet protocol allows the DCC manufacturers that use it to select what functionality they wish to provide in their command stations. This functionality ranges from "supports all features" to "bare bones minimal". Unfortunately, this restricts the features you can access via JMRI - if the hardware doesn't support it, it isn't there to be used by JMRI. In general, the features that JMRI cares about can be grouped into three areas - operating locomotives and turnouts on the layout, programming decoders on a programming track or in ops mode, and getting feedback from the layout (the state of turnouts, ops-mode feedback, etc). The following table tries to show what systems support these features. System specific limitations are also expressed in the Limitations section of this page