R70SR SNAP SIGNAL™ Serial Data Radio
June 23, 2023
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Serial Broadcast Mode
—Broadcast mode allows for more flexible radio layouts and is used in the star and MultiHop tree topologies. These
topologies are much more flexible but they are slower. When using broadcast mode, a small percentage of data packets will not be reach
their destination. Broadcast mode requires the application layer to automatically retry packets that time out. In networks with multiple server,
the client radio must use broadcast mode, but the server radios can be set to use routing mode to route their data packets back to the client
radio. In broadcast mode, the radios route serial data packets to all devices in the network. In general, this mode will have slower communi
cation speeds but will allow for much more system flexibility. If the servers and repeaters are in broadcast mode, they route serial data pack
ets to all other devices and listen to serial data packets coming from all devices. If the client radio is in broadcast mode, it routes serial data
packets to all servers and repeaters and listens to serial data packets coming from all devices.
Transmit Power Levels
—The 900 MHz radios transmit at 1 Watt (30 dBm) or 250 mW (24 dBm). The 250 mW mode reduces the radio's
range, which can help avoid cross talk in areas with multiple systems. For 2.4 GHz models, this DIP switch is disabled. The transmit power
for 2.4 GHz is fixed at about 65 mW EIRP (18 dBm).
Network Topologies in Serial Mode
Cable Replacement Configuration for Point-to-Point Networks--In this simple cable replacement application, the radio system knows all data
originating at one end must be transmitted to the other end. This allows the radio system to automatically correct for transmission problems
and it also provides the greatest throughput. This is the fastest configuration.
Simple point-to-point network
Client radio
Server radio
Device Settings
DIP Switches
1
2
3
4
Client configuration route to a server
Off
Off
Off
On
Server configuration route to the client
Off
Off
Off
Off
Cable Replacement with a Repeater
In this simple cable replacement application with a repeater, the radio system still knows all data origi
nating at one end must be transmitted to the other end. In this application, there are no serial devices connected to the repeater(s). The sys
tem still corrects for transmission problems, but it takes time to repeat the message. The network delay is double that of a system with no re
peater.
Point-to-point network with repeater
Client radio
Server radio
Repeater radio
Device Settings
DIP Switches
1
2
3
4
Client configuration route to a server
Off
Off
Off
On
Repeater configuration
Off
On
On
Off
Server configuration route to the client
Off
Off
Off
Off
Serial Broadcast Mode Configuration with a Star Network
--In this more complex star topology, the client radio at the center of the network
can communicate to many server radios. A common example would be a PLC at the center communicating with many remote I/O systems.
The star topology is slower than a point-to-point network, but faster than a tree network.
© Banner Engineering Corp.
