Echelon DM-21 Device Manager - Manual (Page 12)

1-8 DM-20/21 Overview
The application programmer must follow the convention that a node will not
transmit while it is in the hard-offline state. This means that the application
must trap the state change and verify that the node is not hard offline prior to any
network transmission.
The run_unconfigured pragma is incompatible with most self-installation
schemes, as it may cause a state semaphore error in the Neuron Chip error log,
eventually causing the node to go unconfigured. This problem should not present
itself in a system managed by a Device Manager unless the designer implements a
self-installation feature above and beyond the functions performed by the Device
Manager.
Device Manager Runtime Behavior
Once a LonMaker database has been compressed and loaded into the Device
Manager and the Device Manager is reset, it will immediately begin managing
the devices it discovers on the network as follows:
1. The Device Manager will self-install itself and select the subsystem it will
manage based on the 4-bit input.
2. The Device Manager will go into “discovery mode” and try to locate each
device defined in the subsystem. In multi-channel systems, the Device
Manager will always try to locate the router first. If a router was defined in
the subsystem, but is not physically present on the network, the Device
Manager will not look for the other devices until the router has been
discovered.
3. Devices will be commissioned by the Device Manager as they are discovered.
From the perspective of the device, the commissioning process is
indistinguishable from being commissioned by an LNS tool such as LonMaker
for Windows. In essence, the Device Manager acts as a proxy for an LNS
installation tool.
4. Once a device has been found and commissioned, the Device Manager will
query (“ping”) the device to ensure the device is still operating. If a device
fails to respond to a ping, the Device Manager reenters discovery mode and
attempts replacement for the missing device (matching on Program ID and
location)
If devices are to be added to the network after the Device Manager has been
commissioned, the Device Manager will continue to search for the devices
that it has not yet discovered but which are expected to be present on the
network based on the loaded database.
Discovery
A device is considered to be discovered after the Device Manager receives the
device’s Neuron ID (either via the discovery process or service pin message) and
successfully reads the device’s Program ID and location string. Upon discovery,
an association is established between the discovered device’s Neuron ID and a
record in the Device Manager’s Managed Device List. The discovery is recorded in
the Device Manager’s internal event log and a value of
DMREP_DEVICE_DISCOVERED
is sent on the DM_report network variable.