XBP09-DPUIT-156 Digi International, XBP09-DPUIT-156 Datasheet - Page 31

• 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
Configuration
Sleep Guard Times
Auto-Early Wakeup Sleep Option
Selecting Sleep Parameters
Note #1: For normal operations a module will use the sleep and wake parameters it gets from the
sleep sync message, not the ones specified in its SP and ST parameters. The SP and ST
parameters are not updated with the values of the sync message. It is not necessary for all nodes
in the network to have the same SP and ST parameters. The current network sleep and wake time
that the node is currently using can be queried with the OS and OW commands.
Note #2: Changing network parameters can cause a node to become a sleep coordinator
andchange the sleep settings of the network. The following commands may cause this to occur:
NH,NN, NQ, and MR. In most applications these network parameters should only be configured
during deployment.
To compensate for variations in the timekeeping hardware of the various modules in a
sleepingrouter network sleep guard times are allocated at the beginning and end of the wake time.
The size of these sleep guard times vary based on the sleep and wake times selected and the
number of cycles that have elapsed since the last sync message was received. These sleep guard
times guarantee that a destination radio will be awake when a transmission is initiated. As more
and more consecutive sync messages are missed the sleep guard times increase in duration and
decrease the available transmission time.
In a similar manner to the sleep guard times the auto-early wakeup option decreases the sleep
period based on the number of sync messages missed. This function guarantees that the module
will be awake when the sync message is sent. This option comes at the expense of battery life.
This option can be disabled using the sleep options (SO) command.
Choosing proper sleep parameters is important to create a sleep-enabled network which will be
robust and have the desired battery life. The following steps can be taken to select sleep
parameters which will be good for most applications:
1. Choose NN and NH. Based on the placement of the nodes in your network select appropriate
values for the Network Hops (NH) and Network Delay Slots (NN) parameters.
Note: The default values of NH and NN have been optimized to work for the majority of network
deployments. In most cases it is suggested that these parameters are not modified from the
default values. Decreasing these parameters for small networks can improve battery life but care
should be taken so that the values are not made too small.
2. Calculate the Sync Message Propagation Time (SMPT). This is the maximum amount of
time it takes for a sleep synchronization message to propagate to every node in the network. This
number can be estimated with the following formula:
SMPT = NN * NH * (MT+1) * 18mSec.
3. Select desired duty cycle. The ratio of sleep time to wake time is the factor that has the
greatest effect on the RF module's power consumption. Battery life can be estimated based on the
following factors: sleep period, wake time, sleep current, TX current, RX current, and battery
capacity.
4. Choose Sleep Period and Wake Time. The wake time needs to be long enough to transmit
the desired data as well as the sync message. The ST parameter will automatically adjust upwards
to its minimum value when other AT commands are changed that will affect it (SP, NN, and NH). It
is suggested that a value larger than this minimum is used. If a module misses successive sync
messages it reduces its available transmit time to compensate for possible clock drift. It is wise to
budget a large enough ST time to allow for a few sync messages to be missed and still have time
for normal data transmissions.
© 2009 Digi International, Inc.
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