XBP24-DMWIT-250 Digi International, XBP24-DMWIT-250 Datasheet - Page 24

• 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
Transmission Timeouts
When a node receives an API TX Request (API configured modules) or an RO timeout occurs (modules configured for Transparent
Mode) the time required to route the data to its destination depends on a number of configured parameters, whether the trans-
mission is a unicast or a broadcast, and if the route to the destination address is known. Timeouts or timing information is pro-
vided for the following transmission types:
•
•
•
•
Note: The timeouts in this section are theoretical timeouts and not precisely accurate. The application should pad the
calculated maximum timeouts by a few hundred milliseconds. When using API mode, Tx Status API packets should be the
primary method of determining if a transmission has completed.
Unicast One Hop Time
Transmitting a broadcast
Transmitting a unicast with a known route
Transmitting a unicast with an unknown route
Transmitting a unicast with a broken route
A building block of many of the calculations presented below is the unicastOneHopTime. As its name indicates, it represents
the amount of time it takes to send a unicast transmission between two adjacent nodes. It is largely dependent upon the
mac retry setting (RR). DigiMesh networks assume that the average number of mac level retries across a multi-hop wire-
less link will be 3 or less. It is defined as follows:
A broadcast transmission must be relayed by all routers in the network. The maximum delay would be when the sender and
receiver are on the opposite ends of the network. The NH, NN, and MT parameters define the maximum broadcast delay as
follows:
When a route to a destination node is known the transmission time is largely a function of the number of hops and retries.
The timeout associated with a unicast assumes the maximum number of hops is necessary (as specified by NH). The time-
out can be estimated in the following manner:
If the route to the destination is not known the transmitting module will begin by sending a route discovery. If the route
discovery is successful and a route is found then the data is transmitted. The timeout associated with the entire operation
can be estimated as follows:
If the route to a destination node has changed since the last time a route discovery was completed a node will begin by
attempting to send the data along the previous route. After it fails a route discovery will be initiated and, upon completion
of the route discovery, the data will be transmitted along the new route. The timeout associated with the entire operation
can be estimated as follows:
Transmitting a broadcast
Transmitting a unicast with a known route
Transmitting a unicast with an unknown route
Transmitting a unicast with a broken route.
(mac retries)
RR
0
1
2
3
BroadcastTxTime=NN*NH*(MT+1)* 18ms
knownRouteUnicast=2*NH*MR*unicastOneHopTime
unknownRouteUnicast=BroadcastTxTime+NH*unicastOneHopTime +knownRouteUnicast
brokenRouteUnicast=BroadcastTxTime+NH*unicastOneHopTime +2*knownRouteUnicast
© 2010 Digi International, Inc.
unicastOneHopTime = 24ms
unicastOneHopTime = 40ms
unicastOneHopTime = 63ms
unicastOneHopTime = 5ms
24