User's Manual
Table Of Contents
- 1. Overview
- 2. RF Module Operation
- 3. XBee ZigBee Networks
- Introduction to ZigBee
- ZigBee Stack Layers
- Networking Concepts
- ZigBee Application Layers: In Depth
- Coordinator Operation
- Router Operation
- End Device Operation
- Channel Scanning
- 4. Data Transmission, Addressing, and Routing
- 5. Security
- 6. Network Commissioning and Diagnostics
- 7. Managing End Devices
- 8. XBee Analog and Digital IO Lines
- 9. API Operation
- API Frame Specifications
- API UART Exchanges
- Supporting the API
- API Frames
- AT Command
- AT Command - Queue Parameter Value
- ZigBee Transmit Request
- Explicit Addressing ZigBee Command Frame
- Remote AT Command Request
- Create Source Route
- AT Command Response
- Modem Status
- ZigBee Transmit Status
- ZigBee Receive Packet
- ZigBee Explicit Rx Indicator
- ZigBee IO Data Sample Rx Indicator
- XBee Sensor Read Indicator
- Node Identification Indicator
- Remote Command Response
- Over-the-Air Firmware Update Status
- Route Record Indicator
- Many-to-One Route Request Indicator
- Sending ZigBee Device Objects (ZDO) Commands with the API
- Sending ZigBee Cluster Library (ZCL) Commands with the API
- Sending Public Profile Commands with the API
- 10. XBee Command Reference Tables
- 11. Module Support
- Appendix A: Definitions
- Appendix B: Agency Certifications
- United States FCC
- OEM Labeling Requirements
- FCC Notices
- FCC-Approved Antennas (2.4 GHz)
- Europe (ETSI)
- OEM Labeling Requirements
- Restrictions
- Declarations of Conformity
- Approved Antennas
- XBee RF Module
- XBee-PRO (S2) RF Module
- XBee-PRO (S2B) RF Module
- Canada (IC)
- Transmitters for Detachable Antennas
- Detachable Antenna
- Appendix C: Migrating from ZNet 2.5 to XBee ZB
- Appendix D: Additional Information
XBee®/XBee‐PRO®ZBRFModules
©2009DigiInternational,Inc. 56
Maximum RF Payload Size
XBee ZB firmware includes a command (ATNP) that returns the maximum number of RF payload
bytes that can be sent in a unicast transmission. Querying the NP command, like most other
commands, returns a HEXADECIMAL value. This number will change based on whether security is
enabled or not. If security is enabled (EE command), the maximum number of RF payload bytes
decreases since security requires additional overhead.
After reading the NP value, the following conditions can affect the maximum number of data bytes
in a single RF transmission:
• Broadcast transmissions can support 8 bytes more than unicast transmissions.
• If source routing is used, the 16-bit addresses in the source route are inserted into the RF
payload space. For example, if NP returns 84 bytes, and a source route must traverse 3 inter-
mediate hops (3 16-bit addresses), the total number of bytes that can be sent in one RF
packet is 78.
• Enabling APS encryption (API tx option bit set) will reduce the number of payload bytes by 4.
Throughput
Throughput in a ZigBee network can vary by a number of variables, including: number of hops,
encryption enabled/disabled, sleeping end devices, failures/route discoveries. Our empirical
testing showed the following throughput performance in a robust operating environment (low
interference).
Data Throughput*
RR = router to router,
RE = router to end device (non-sleeping),
ER = end device (non-sleeping) to router,
SD = security disabled,
SE = security enabled.
4 hops = 5 nodes total, 3 intermediate router nodes
* Data throughput measurements were made setting the serial interface rate to 115200 bps, and
measuring the time to send 100,000 bytes from source to destination. During the test, no route
discoveries or failures occurred.
ZDO Transmissions
ZigBee defines a ZigBee Device Objects layer (ZDO) that can provide device and service discovery
and network management capabilities. This layer is described below.
Configuration Data Throughput
1 hop, RR, SD 35kbps
1 hop, RR, SE 19kbps
1 hop, RE, SD 25kbps
1 hop, RE, SE 16kbps
1 hop, ER, SD 21kbps
1 hop, ER, SE 16kbps
4 hops, RR, SD 10kbps
4 hops, RR, SE 5kbps