Turnout control from
a wireless panel
Overview:
The availability of low cost hand held devices like the
iPod Touch and iPad have made it practical for wireless
turnout control panels. JMRI provides the means for this
type of control with its web access support. So
theoretically any device with a web browser could be
used. Ajax (Asynchronous Javascript And XML) is the
tool that makes this scheme possible. It allows a web
page to be more responsive and act like a regular
computer application.
Ajax expects the client (web browser, user) to initiate
actions. This presents a challenge in controlling
turnouts. In the case of a throttle no one else (i.e.
just one person) should be controlling the engine.
However, in the case of a turnout it could be controlled
from any number of sources. If the turnout is changed
from some other source you would like that change
reflexed in the device you are using. The goal is to
provide reliable and consistent turnout state indication
with all devices if one device makes a change.
Here are some examples using the iPod Touch in
controlling turnouts and location of trains. Icons are
from the JMRI resource directory.
This example shows a scheme of controlling turnouts that
are used frequently. Individual turnout addresses can be
entered or a group of numbers can be entered from a popup
menu.
These examples show a scheme of controlling turnouts from
a panel diagram. You can change web pages as you walk
around a layout. Knowing the turnout numbers is not
required. Just touch the turnout symbol and change the
turnout state. Route buttons are used to control several
turnouts.
The following pictures show snap shots of a train
entering a hidden yard, bypassing the yard, turning
around in the reverse loop and stopping in track 2. Route
buttons are used to control the turnouts to select the
yard track to enter. The short blocks in each yard track
are the stopping blocks. The red segments indicate an
occupied block (not necessarily the length of the block).
Only a few are shown here. The blue numbers are the
number of the locomotive stored on that track and are
read from and written to memory variables in the JMRI
(2.11.5 and later).
