XBP09-DPUIT-156 Digi International, XBP09-DPUIT-156 Datasheet - Page 33

• Manufacturer Part Number: XBP09-DPUIT-156
• Description: MODULE XBEE PRO W/U.FL
• Manufacturer: Digi International
• Series: XBEE-PRO™r

Specifications of XBP09-DPUIT-156

• Frequency: 902MHz ~ 928MHz
• Data Rate - Maximum: 156kbps
• Modulation Or Protocol: FHSS
• Applications: ISM
• Power - Output: 17dBm (50mW)
• Sensitivity: -100dBm
• Voltage - Supply: 3 V ~ 3.6 V
• Current - Receiving: 80mA
• Current - Transmitting: 210mA
• Data Interface: PCB, Through Hole
• Antenna Connector: U.FL
• 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: 602-1168

XBee‐PRO® 900 RF Modules
Changing Sleep Parameters
Rejoining Nodes Which Have Lost Sync
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 parameters, 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:
1. Whenever possible, avoid changing sleep parameters.
2. Enable the missed sync early wakeup sleep option (SO). This command is used to tell a node to
wake up 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-synced node will be awake when the
network wakes up and sends the sync message.
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.
3. When changing between two sets of sleep settings, choose settings so that the wake periods of
the two sleep settings will happen at the same time. In other words, try to satisfy the following
equation: (SP1 + ST1) = N*(SP2+ST2), where SP1/ST1 and SP2/ST2 are the desired sleep
settings and N is an integer.
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 parameters will have to wait many cycles before it gets another chance
to hear the sync message.
available in a network. 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:
Mesh networks get their robustness from taking advantage of routing redundancies which may be
© 2009 Digi International, Inc.
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