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DNT2400 - 08/18/09
radio automatically renews the lease with the base. There is nothing the remote host needs to do to keep
the lease renewed. Note that more remotes can join the network but their entering and leaving the net-
work cannot be tracked by the base radio. The DNT2400 base can be configured to send join announce-
ments to a host application for an unlimited number of remotes. The application can then verify the con-
tinued presence of remotes in the network through periodic polling of each remote.
In addition, the DNT2400 supports a RemoteLeave command that allows a host application to cause a
remote to leave the network. This is useful to remove any rogue remotes that may have joined when
authentication is not being used. It is also useful to remove remotes from the network once they have
been serviced by the application. In this manner, the base can use the lease times to keep track of re-
motes that have not yet been serviced thereby allowing networks of more than 254 remotes to be tracked.
The RemoteLeave command includes the amount of time the remote must leave the network which can
be set from 2 seconds to more than 36 hours. In addition, a remote can be told to leave and not rejoin
until it has been power-cycled or reset.
2.2 Authentication
In many applications it is desirable to control which remote devices may join the network. This provides
security from rogue nodes joining the network and simplifies network segregation for co-located networks.
Network registration of remotes is controlled by the AuthMode parameter in the base. The AuthMode
parameter can be set to one of four values, 0..3. The default value is 0, which allows any remote to regis-
ter with a base.
When the AuthMode parameter is set to 1, a remote’s address must be listed in Parameter Bank 7 before
it will be allowed to register with the base. This is referred to as base authentication. Bank 7 must be
preloaded with the addresses of the authorized remotes before using base authentication. If a remote
whose MAC address is not in Bank 7 attempts to join the network the base radio will deny the registration
request. A maximum of 16 remotes can be entered into Bank 7. To support larger networks, mode 2 must
be used.
When the AuthMode parameter is set to 2, the address of a remote attempting to register with the base is
sent to the host for authentication in a JoinRequest message. The host application determines if the
remote should be allowed to register and returns a JoinReply message to the base containing a Permit-
Status parameter that allows or blocks the remote from registering. The host application has 30 seconds
in which to respond, after which time the base denies registration to the remote. Up to 16 join requests
can be pending at any one time. If more than 16 remotes are asking to join, the first 16 will be serviced
and additional remotes will be serviced after the earlier requests are handled. The RegDenialDelay pa-
rameter controls how often a remote will request registration after it has been denied. If it is anticipated
that more than 16 remotes will request registration before the application can service the first 16, this
parameter should be set to the time it will take the application to service four requests as this will speed
the authentication process by freeing the base from issuing multiple denials to the same remotes.
When the AuthMode parameter is set to 3, authentication is locked to the addresses of the remotes
currently registered with the base. Mode 3 is typically used in conjunction with Mode 0 during a commis-
sioning process. AuthMode is set to 0, remotes are turned on and allowed to register with the base, and
AuthMode is then switched to 3 to lock the network membership.
