User Manual

Global Transceiver Module (GXM) Wireless Data Transceiver User Manual
LUM0031AA
Version 1.0 38
MultiPoint Parameters
When installing MultiPoint networks it is important to do some up front planning. Unlike Point-to-Point
networks, a Point-to-MultiPoint network requires several parameters are set consistently on all
transceivers in the network. This includes RF data rate, Min and Max Packet Size, and FreqKey.
Note: If several independent MultiPoint networks are to be located in close proximity the planning
becomes more critical. In such cases, it becomes very important to include as much frequency
and time diversity as possible through use of different FreqKey, Min and Max Packet Size, and
Hop Table settings. In some instances the use of the MultiMaster Synch option may be required.
Edit MultiPoint Parameters
Selecting (5) Edit MultiPoint Parameters from the main menu displays the following window:
(0)
NUMBER REPEATERS
In a MultiPoint network it is critical to transmission timing to configure this parameter correctly. The value
should be 0 if no Repeaters are in the network and 1 if any number of Repeaters are present. This
parameter is used only in the MultiPoint Master radio.
(1)
MASTER PACKET REPEAT
In a Point-to-MultiPoint network, Slaves do not acknowledge transmissions from the Master. If Slaves did
acknowledge all data transmissions, in a large network, the Master would soon become overwhelmed
with acknowledgments from the Slaves. Without acknowledgements, 100% confidence every Slave has
received every packet cannot be met. To address this issue, the user may modify the Master Packet
Repeat setting, assigning a value between 0 (the packet is transmitted once) to 9 (the packet is
transmitted 10 times). For networks with solid RF links, this parameter should be set to a low value such
as 1 or 2. If a network has some weak or marginal links it should be set with higher values. If a Slave
receives a good packet from a Master more than once it will discard the repeated packets. Similarly, once
a MultiPoint Repeater receives a good packet from the Master, it will discard any further repeated
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