Echelon IzoT NodeBuilder - Manual (Page 24)

channels that use different media (channel types) together. Unlike other devices, routers are always
attached to at least two channels.
The IzoT Router can be configured to act as a DHCP relay for address allocation on the LonTalk/IP
network. DHCP relay can be used to have a single server perform all of the allocation of addresses in
a network, and then have the server’s allocations forwarded onto another subnet.
To enable the DHCP relay functionality, go to the DHCP page on configuration Web page of the IzoT
Router. Once there, select the Relay option and a box to enter the address of the DHCP server
appears. Enter the IP address of your server and click the Save Configuration button. DHCP requests
are now forwarded from the LonTalk/IP network to the DHCP server, and responses from the server
will be forwarded to devices on the LonTalk/IP network.
The DHCP server must have a separate subnet set up to allocate addresses from the LonTalk/IP subnet.
This is because the IzoT Router treats the IP and LonTalk/IP subnets as separate subnets, and uses the
subnets to determine which subnet to send messages on. The subnet on the FT side needs to be
different than the subnet on the Ethernet side. If both the LonTalk/IP and IP subnets share the same
address range, the router cannot determine where to send the messages.
Applications
Every IzoT and L ON W ORKS device contains an application that defines the device’s behavior. The
application defines the inputs and outputs of the device. The inputs to a device can include
information sent on LonTalk/IP and L
ON W ORKS channels from other devices, as well as information
from the device hardware (for example, the temperature from a temperature sensing device). The
outputs from a device can include information sent on LonTalk/IP and L
ON W ORKS channels to other
devices, as well as commands sent to the device hardware (for example, a fan, light, heater, or
actuator). You can use the IzoT NodeBuilder tool to write a device’s Neuron C application.
Program IDs
Every L ON W ORKS application has a unique, 16 digit, hexadecimal standard program ID with the
following format: FM:MM:MM:CC:CC:UU:TT:NN. This program ID is broken down into the
following fields:
Field Description
Format (F) A 1 hex-digit value defining the structure of the program ID. The upper
bit of the format defines the program ID as a standard program ID (SPID)
or a text program ID. The upper bit is set for standard program IDs, so
formats 8–15 (0x8–0xF) are reserved for standard program IDs.
• Program ID format 8 is reserved for L
ON M ARK certified devices.
• Program ID format 9 is used for devices that will not be L
ON M ARK
certified, or for devices that will be certified but are still in
development or have not yet completed the certification process.
• Program ID formats 10–15 (0xA–0xF) are reserved for future use.
• Text program ID formats are used by network interfaces and legacy
devices and, with the exception of network interfaces, cannot be used
for new devices.
The IzoT NodeBuilder tool can be used to create applications with
program ID format 8 or 9.
Manufacturer ID (M) A 5 hex-digit ID that is unique to each L ON W ORKS device manufacturer.
The upper bit identifies the manufacturer ID as a standard manufacturer
ID (upper bit clear) or a temporary manufacturer ID (upper bit set).
10 Introduction