Specifications
XBee®/XBee‐PRO®SERFModules
©2009DigiInternational,Inc. 84
Data bytes that need to be escaped:
• 0x7E – Frame Delimiter
•0x7D – Escape
• 0x11 – XON
• 0x13 – XOFF
Example - Raw UART Data Frame (before escaping interfering bytes):
0x7E 0x00 0x02 0x23 0x11 0xCB
0x11 needs to be escaped which results in the following frame:
0x7E 0x00 0x02 0x23 0x7D 0x31 0xCB
Note: In the above example, the length of the raw data (excluding the checksum) is 0x0002 and
the checksum of the non-escaped data (excluding frame delimiter and length) is calculated as:
0xFF - (0x23 + 0x11) = (0xFF - 0x34) = 0xCB.
Length
The length field has a two-byte value that specifies the number of bytes that will be contained in
the frame data field. It does not include the checksum field.
Frame Data
Frame data of the UART data frame forms an API-specific structure as follows:
UARTDataFrame&API‐specificStructure:
The cmdID frame (API-identifier) indicates which API messages will be contained in the cmdData
frame (Identifier-specific data). Note that multi-byte values are sent big endian. The XBee
modules support the following API frames:
Tabl e8‐01. APIFrameNamesandValu e s
API Frame Names API ID
AT Command
0x08
AT Command - Queue Parameter Value
0x09
Explicit Addressing ZigBee Command Frame 0x11
ZigBee Create Source Route
0x21
ZigBee Register Joining Device
0x24
AT Command Response
0x88
Modem Status 0x8A
ZigBee Transmit Status 0x8B
ZigBee Explicit Rx Indicator (AO=1) 0x91
Route Record Indicator
0xA1
Device Authenticated Indicator
0xA2
Many-to-One Route Request Indicator
0xA3
ZigBee Register Joining Device Status
0xA4
Length
(Bytes 2-3)
Checksum
(Byte n + 1)
MSB LSB 1 Byte
Start Delimiter
(Byte 1)
0x7E
Frame Data
(Bytes 4-n)
API-specific Structure
Identifier-specific Data
cmdData
API Identifier
cmdID