User guide
SATELLINE-3AS NMS / NMS Epic / NMS 869 / VHF
User Guide, Version 1.0
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8.3.3
Protocol support
Using the internal
Packet filter
feature the radio modem catches and transfers only the wanted
messages/protocols - NMS also enables easy addition of higher level functions, like alternative
routes and alarms in future development. The list of preset protocols includes for example:
• User defined
• Modbus ASCII
• Modbus RTU
• Rockwell DT1
• IEC60870-5-101
• DNP 3.0
• ANSI
• SATELLINK
8.3.4
Network ID
The Network ID is a character string which is used to prevent the reception of the messages
coming from any external system. It applies only in the
Advanced Protocol modes
. The radio
modems operating in the same system using
NMS Routing
must have the same Network ID.
Only the messages that have a matching Network ID are received. Network ID is configured by
using SATEL NMS PC.
8.4
Repeater stations
In circumstances where it is necessary to extend the coverage area of a radio modem network,
SATELLINE-3AS(d) NMS / NMS Epic / NMS 869 / VHF radio modems can be used as repeater
stations. The same network may include several repeaters, which operate under the same base
station. Repeaters may also be chained; in which case a message is transmitted through several
repeaters. In systems with more than one serial or parallel-chained repeater, addressing or
routing protocol must be used to prevent a message ending up in an infinite loop formed by
repeaters, and to ensure that the message finally reaches only the intended radio modem.
The maximum size of a repeated data packet is 1kB (kilobyte).
A radio modem acting as a repeater can be also connected to the serial interface:
• The radio modem in the
Basic-Repeater Protocol mode
will transmit all the received
messages to the serial interface.
• The radio modem in the
Advanced-Master
or
Advanced-Slave
mode will transmit only the
received messages addressed to its serial interface dictated by the route information in the
message and the settings of the radio modem.
• The radio modem will transmit the data coming from the serial interface in a normal format
in all
Protocol modes
.