Kantronics KPC–3 Plus User Manual page 144

program which is used in the computer of a DAMA master along with one TNC, with a
special EPROM for each radio frequency used on the system. RMNC/FlexNet software
is another program, which is very popular in Germany.
Within each Local Area Network (LAN), end users set themselves up as DAMA ―slaves,‖
using specially equipped TNCs, which contain firmware (EPROM) that can operate in a
DAMA ―slave‖ mode (such as the Kantronics TNCs with DAMA slave mode support).
The slaves may use a standard terminal or host mode program or any of a variety of
specially written European programs, such as SP, Grafik Packet and ESKAY, some of
which make use of the KISS mode feature of the TNC.
To use the DAMA system, the user connects to the DAMA master with a normal
connect frame. When the master responds to the connect frame, the TNC is
automatically placed into DAMA slave mode. The DAMA master polls each slave within
the LAN in a ―round-robin‖ fashion (somewhat like the token passing method) and the
slave TNCs transmit packets when the master has granted permission to do so. The
slave TNCs continue to be polled with priority among the slaves assigned according to
the number of times each responds with information frames (as opposed to rr frames -
i.e., no data to send). Priority is dynamically assigned so that those stations that are
sending information are polled more frequently than idle stations. However, once an
―idle‖ station responds with information, its priority is upgraded.
Communication over the wider area is handled between the DAMA master nodes which
are connected to each other using a standard NET/ROM
system to work effectively, each slave associates with only one master node and
connects only to that master. If an end user is connected to more than one master, each
master will poll the slave TNC according to its polling schedule. When polled, the slave
TNC will transmit all frames it has available to whichever master polls it. This would
increase the probability of collisions with other users, thus defeating the purpose of the
DAMA system.
How is DAMA Implemented in Kantronics' TNCs?
Most Kantronics TNCs, including the KPC-3 Plus, KPC-9612 Plus, and the KAM Plus,
implement the DAMA slave mode, using the following commands (see the Command
Reference section for details):
DAMA {ON|OFF}
Set DAMA to ON to have your Kantronics TNC operate as a DAMA slave station once a
connection is established with a DAMA master station. When DAMA is OFF, the TNC
will operate in its carrier-sense-multiple-access mode (CSMA). For details, see the CD,
SLOT, and PERSIST commands in the Command Reference section of this manual.
DAMACHCK n (n = 0 to 225)
Set a ―DAMA time-out‖ timer (in 10-second increments) to specify how long your TNC
(running in DAMA slave mode) will wait to be polled by a connected DAMA station
before disconnecting from the DAMA station and reverting to CSMA operation.
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type protocol. For the DAMA
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