Echelon LonTal Stack - Manual (Page 69)

LonTalk Stack Developer’s Guide 57
You can minimize the need for type translators by using standard network
variable types (SNVTs) for commonly used types, and by using changeable-type
network variables, where appropriate. You can also define your own user
network variable types (UNVTs).
You can use the NodeBuilder Resource Editor to look through the standard
network variable types, as described in Defining a Resource File, or you can
browse the standard profiles online at types.lonmark.org .
You can connect network variables on different devices that are of identical type,
but opposite direction, to allow the devices to share information. For example, an
application on a lighting device could have an input network variable of the
switch type, while an application on a dimmer-switch device could have an
output network variable of the same type. You can use a network tool, such as
OpenLNS Commissioning Tool, to connect these two devices, allowing the switch
to control the lighting device, as shown in the following figure.
A single network variable can be connected to multiple network variables of the
same type but opposite direction. The following figure shows the same switch
being used to control three lights.
The LonTalk Stack application in a device does not need to know anything about
where input network variables come from or where output network variables go.
After the LonTalk Stack application updates a value for an output network
variable, it uses a simple API function call to have the LonTalk host stack
propagate it.
Through a process called binding that takes place during network design and
installation, the LonTalk Stack is configured to know the logical address of the