XBP09-DPUIT-156 Digi International, XBP09-DPUIT-156 Datasheet - Page 30

• 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
Becoming a Sleep Coordinator
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A node can become a sleep coordinator in one of four ways:
Preferred Sleep Coordinator Option
A node can be specified to always act as a sleep coordinator. This is done by setting the
preferredsleep coordinator bit (bit 0) in the sleep options parameter (SO) to 1. A node with the
preferred sleep coordinator bit set will always send a sync message at the beginning of a wake
cycle. For this reason it is imperative that no more than one node in the network has this bit set.
Although it is not necessary to specify a preferred sleep coordinator, it is oftentimes advantageous
to select a node for this purpose to improve network performance. A node which is centrally
located in the network can serve as a good sleep coordinator to minimize the number of hops a
sync message must take to get across the network. A sleep support node and/or a node which is
mains powered may also be a good candidate.
The preferred sleep coordinator bit should be used with caution. The advantages gained by
usingthe option on an appropriate node become weaknesses to the network when used on a node
which is not positioned or configured appropriately. The preferred sleep coordinator option can
also be used when setting up a network for the first time. When starting a network a node can be
configured as a sleep coordinator so it will begin emitting sync messages. After the network is
setup the preferred sleep coordinator bit can be disabled.
Nomination and Election
Nomination is an optional process that can occur on a node in the event that contact with the
network sleep coordinator is lost. By default this behavior is disabled. This behavior can beenabled
with the sleep options command (SO). This process will automatically occur in the event that
contact with the previous sleep coordinator is lost. Any sleep compatible node which has this
behavior enabled is eligible to become the sleep coordinator for the network. If a sleep compatible
node has missed three or more sync messages and is not configured as a non-sleep coordinator
(presumably because the sleep coordinator has been disabled) it may become a sleep coordinator.
Depending on the platform and other configured options such a node will eventually nominate
itself after a number of cycles without a sync. A nominated node will begin acting as the new
network sleep coordinator. It is possible for multiple nodes to nominate themselves as the sleep
coordinator. If this occurs then an election will take place to establish seniority among the multiple
sleep coordinators. A node will cease being the sleep coordinator if it receives a sync message
from a senior node. Seniority is determined on the basis of four factors (in order of priority):
1. Newer sleep parameters: a node using newer sleep parameters (SP/ST) is considered senior toa
node using older sleep parameters. (See the Changing Sleep Parameters section below).
2. Preferred Sleep Coordinator: a node acting as a preferred sleep coordinator is senior to other
nodes.
3. Sleep Support Node: sleep support nodes are senior to cyclic sleep nodes. (This behavior can be
modified using the SO parameter)
4. Serial Number: in the event that the above factors do not resolve seniority then the node with
the higher serial number is considered senior.
Commissioning Button
The commissioning button can be used to select a module to act as the sleep coordinator. If the
commissioning button functionality has been enabled a node can be immediately nominated as a
sleep coordinator by pressing the commissioning button twice or by issuing the CB2 command. A
node nominated in this manner is still subject to the election process described previously. Nodes
which are configured as a non-sleep coordinator will ignore commissioning button nomination
requests.
Changing Sleep Parameters
Any sleep compatible node in the network which does not have the non-sleep coordinator sleep
option set can be used to make changes to the network's sleep and wake times. If a node's SP
and/or ST are changed to values different from those that the network is using then that node will
become the sleep coordinator. That node will begin sending sync messages with the new sleep
parameters at the beginning of the next wake cycle.
© 2009 Digi International, Inc.
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