XBP24-DMWIT-250 Digi International, XBP24-DMWIT-250 Datasheet - Page 30

• Manufacturer Part Number: XBP24-DMWIT-250
• Description: XBEE-PRO MESH 2.4 EXTENDED
• Manufacturer: Digi International
• Series: XBEE-PRO™r

Specifications of XBP24-DMWIT-250

• Frequency: 2.4GHz
• Data Rate - Maximum: 250kbps
• Modulation Or Protocol: ISM
• Applications: General Purpose
• Power - Output: 18dBm
• Sensitivity: -100dBm
• Voltage - Supply: 2.8 V ~ 3.4 V
• Current - Receiving: 55mA
• Current - Transmitting: 250mA
• Data Interface: PCB, Through Hole
• Antenna Connector: On-Board, Wire Whip
• Operating Temperature: -40°C ~ 85°C
• Package / Case: Module
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Memory Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: Q4542387

XBee/XBee‐PRO DigiMesh 2.4 RF Modules
If one of these methods are not used it is necessary to wait for the network to wake up before the new node can be
added. The new node should be placed in range of the network with a sleep period which is shorter than the wake
period of the network. The new node will periodically send sync requests until the network wakes up and it receives
a sync message.
Changes to the sleep and wake cycle of the network can be made by selecting any node in the network and changing
the SP and/or ST of the node to values different than those that the network is currently using. If using a preferred
sleep coordinator or if it is known which node is acting as the sleep coordinator it is suggested that this node be used
to make changes to network settings. If the network sleep coordinator is not known then any node that does not
have the non-sleep coordinator sleep option bit set (see the SO command) can be used.
When changes are made to a node's sleep parameters that node will become the network's sleep coordinator (unless
it has the non-sleep coordinator option selected) and will send a sync message with the new sleep settings to the
entire network at the beginning of the next wake cycle. The network will immediately begin using the new parame-
ters, after this sync is sent.
Changing sleep parameters increases the chances that nodes can lose sync. If a node does not receive the sync
message with the new sleep settings then it will continue operating on its old settings. To minimize the risk of a node
losing sync and to facilitate the re-syncing of a node that does lose sync the following precautions can be taken:
Note: Using this sleep option increases reliability but may decrease battery life. Nodes using this sleep option which miss
sync messages will have an increased wake time and decreased sleep time during the cycles in which the sync message
is missed. This will reduce battery conservation.
In the good example, a node which misses a sync changing the sleep parameters will get a chance to receive a sync
message after 2 of the shorter cycles. In the bad example, a node which misses a sync changing the sleep parame-
ters will have to wait many cycles before it gets another chance to hear the sync message.
work. It is recommended to architect the network with redundant mesh nodes to increase robustness. If a scenario
exists such that the only route connecting a subnet to the rest of the network depends on a single node, and that
node fails--or the wireless link fails due to changing environmental conditions (catastrophic failure condition), then
multiple subnets may arise while using the same wake and sleep intervals. When this occurs the first task is to
repair, replace, and strengthen the weak link with new and/or redundant modules to fix the problem and prevent it
from occurring in the future.
When the default DigiMesh sleep parameters are used separated subnets will not drift out of phase with each other.
Subnets can drift out of phase with each other if the network is configured in one of the following ways:
Changing Sleep Parameters
Rejoining Nodes Which Have Lost Sync
Mesh networks get their robustness from taking advantage of routing redundancies which may be available in a net-
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progressively earlier every cycle based on the number of cycles it has gone without receiving a sync. This will
increase the probability that the un-synchronized node will be awake when the network wakes up and sends
the sync message.
settings will happen at the same time. In other words, try to satisfy the following equation:
When changing between two sets of sleep settings, choose settings so that the wake periods of the two sleep
Whenever possible, avoid changing sleep parameters.
Enable the missed sync early wakeup sleep option (SO). This command is used to tell a node to wake up
(SP1 + ST1) = N*(SP2+ST2), where SP1/ST1 and SP2/ST2 are the desired sleep settings and N is an
integer.
If multiple modules in the network have had the non-sleep coordinator sleep option bit disabled and are
thus eligible to be nominated as a sleep coordinator.
If the modules in the network are not using the auto early wakeup sleep option.
© 2010 Digi International, Inc.
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