SATELLINE-3AS NMS / Epic NMS / VHF
User Guide, Version 3.0
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over the data transfer of the radio network. The role of the radio modem is then to provide a
plain transparent radio connection. All the messages are received by any other radio modem
using the same settings.
See also the chapters
2.6 Settings
and
11.1Programming Mode
.
8.3
System characteristics
The data transfer characteristics of SATELLINE-3AS NMS / Epic NMS / VHF are designed to fit in
real time systems. The full functionality of NMS is obtained in the user systems that have a single
master polling scheme, where the master station polls every slave station regularly.
8.3.1
Features
o
Transparent to user protocols.
o
Easy construction of a network containing several repeaters.
o
Any radio modem may operate as a repeater, i.e. dedicated repeaters are not usually
needed thus cutting down on costs.
o
Large coverage areas may be implemented by using only one radio channel.
o
The system will be fully deterministic i.e. the transmission delays are predictable. Because
of this, the principle of
NMS Routing
is connectionless.
o
Added redundancy by using NMS, as a failing radio modem can be by-passed with
another radio modem positioned in the same coverage area.
8.3.2
System requirements
o
NMS and the internal routing features are intended mainly for the protocols based on
polling scheme and a single master station. Other kinds of are possible but require
careful planning - contact SATEL in uncertain cases.
o
The maximum size of a single message is 1kB (kilobyte), if repeater stations are used.
o
It is assumed that the position of the address field in the user messages is fixed (some
special protocols can be supported though, and list will be growing).
o
It is assumed that there is only one message at a time inside the network. Simultaneous
messages could cause collisions.
o
The maximum number of the routes depends on the actual hardware and the software
version. Currently the maximum number of routes is 100.