SATELLINE-EASy / SATELLINE-EASy 869
User Guide, Version 3.0
71
14.1.5
Manual configuration of the Message Routing
The radio modems can be configured manually via the programming menu. However, this is
recommended only if the structure of the network is very simple, or if it is desirable to define
such special functions that are not possible to draw using the graphical interface of
SaTerm
.
Examples of such cases are for example non tree-structured networks, or the use of same
repeaters in several overlapping networks. The operation of the
Message Routing
must be clearly
understood before configuring the radio modems manually.
14.1.6
Configuration of the protocol in Message Routing
A radio modem will detect the presence of an address used by inspecting the protocol from the
message received via the serial interface. On the basis of this user address, all necessary
information needed to relay the message to destination is fetched from an internal routing table
inside a radio modem. The user protocol is not interpreted; instead, the user address is searched
according to its location in the message. The beginning of the packet is located by a preceding
pause in the byte stream. Message Routing can therefore be applied to most protocols with fixed
address field position.
The position and length of the address is defined by two settings:
Offset
and
Length
.
•
Offset defines the number of bytes (0…15) preceding the address.
•
Length is the length of the address in the user protocol expressed in bytes (1…4).
A transmitting radio modem adds a routing header and a tail to the user message.
Consequently, a radio modem that receives the message removes the header and tail - so the
Message Routing scheme is transparent to the user protocol.
Offset
Length
Byte length
USER ADDRESS
Start of data packet, Offset=2, Length=3
USER DATA
