JMRI Hardware Support - OpenLCB - Naming

# Hardware Support: OpenLCB - Naming

This page discusses how JMRI uses System Names to access OpenLCB-attached resources.

## JMRI's Use of Names

JMRI provides an interface to the real layout via internal objects such as Turnouts, Sensors, etc. that are closely mapped to corresponding physical devices. This mapping is done via "System Names", which both identify how to access a particular device, and are the key to looking up the corresponding object in JMRI.

## OpenLCB Events

OpenLCB communicates events via messages with a fixed format: eight bytes of content. We convert this to a 16 hexadecimal digit code with a leading "x" character, e.g. "x1234567890ABCDEF". We recommend you use upper case for the A-F letters. You can also enter it with periods separating the bytes: "12.34.56.78.90.AB.CD.EF". In this case only, one leading zero per byte can be omitted when typing the event; JMRI will insert them automatically in names. For example, "00.01.02.03.04.05.06.07" can be typed as "0.1.2.3.4.5.6.7".

## OpenLCB Configuration Memory

DecoderPro accesses decoder memory via "CVs". For that purpose, the JMRI OpenLCB provides a CV syntax that can be used to access OpenLCB node configuration memory:

- CV12345 - A single byte at address 12345 in the default configuration address space
- CV(252)12345 - A single byte at address 12345 in the 252 address space
- CV12345:4 - Four bytes starting at address 12345 in the default configuration address space.
- CV(252)12345:4 - Four bytes starting at address 12345 in the 252 address space.

## OpenLCB Signal Masts

See the OpenLCB Signal Mast page for more information on OpenLCB Signal Mast names.

Back to the main OpenLCB Help page