Echelon LNS - Manual (Page 107)

LNS Programmer's Guide 93
For a device to provide location information to the application, there must be some way
for the device to know its location. For example, each device’s location field can be
programmed with a location code, and each device can be sent to the field with
instructions for where the device is to be attached to the network. Alternately, a hand-
held tool could be used to set the location string of each device at installation time. If the
LNS application contains a table that maps codes to physical locations, the application
can fetch the location code using the AppDevice object’s LocationInNeuron property,
and determine where the device is located.
Another way for a device to determine its location is to provide a way for it to read its
location using I/O pins. You could achieve this by embedding location information at each
attachment site. The network connector could contain a 6-bit connector ID that allows
the device to tell which of 64 connectors it has been attached to. Alternately, a serial ID
device such as a Dallas touch memory could be used to provide a unique ID for each
location while using fewer I/O pins on each application device. The use of I/O pins may
require that device’s program is running, so that it can read the I/O pins. If such
behavior is required, the device must be delivered in the configured state or the device’s
application must use the Neuron C pragma run_unconfigured compiler directive.
There is another method to determine a device’s approximate location. This method is
less precise, as it provides a device’s approximate location, but it is fully automatic. When
using automatic installation, LNS will automatically detect the channel each application
device is attached to, as long as the network only uses configured routers. The channel is
an indicator for the device’s approximate location and may assist with automatic location
detection. Further, if pinging is enabled on the system, the LNS pinging process will
verify the device’s presence on the channel it was previously attached to. See the
Discovering When New Devices are Attached to the Network section later in this chapter
for more details on this.
If a device can determine its own location, it may also be able determine when it has
been moved. This information can be used as part of the installation scenario. For
example, if a temperature sensor is moved from room 1 to room 5, the sensor can tell that
it has moved and, under application control, activate its service pin to issue a "request for
service". When the LNS application receives the service pin event, it can check the
database and see that the device was already installed in the system as part of another
room, and then reconnect the network to make the sensor part of the control scheme for
room 5.
Installing Devices
Once your application has discovered a newly discovered device, you need to define the
device in the LNS database, and connect it to other devices on the network. Depending
on how the device was discovered, the steps required to do so may vary slightly. These
tasks are described below.
Note that if your network uses multiple channels, you will need to install and configure
the network’s routers, and create channels, as you define your devices. For more
information on routers, and on special considerations you may need to make when
installing devices on a network with multiple channels, see Installing Devices With
Multiple Channels on page 175.
1. In several of the device discovery methods described in this section, an
AppDevice
object is added to the
Discovered.Uninstalled
subsystem’s
AppDevices
collection each time a new device is discovered. You need to move each device to