XBee®/XBee‐PRO® ZB SMT RF Modules
Checksum
To test data integrity, a checksum is calculated and verified on non-escaped data.
To calculate: Not including frame delimiters and length, add all bytes keeping only the lowest 8 bits of the
result and subtract the result from 0xFF.
To verify: Add all bytes (include checksum, but not the delimiter and length). If the checksum is correct,
the sum will equal 0xFF.
API Examples
Example: Create an API AT command frame to configure an XBee to allow joining (set NJ to 0xFF). The frame
should look like:
0x7E 0x00 0x05 0x08 0x01 0x4E 0x4A 0xFF 5F
Where 0x0005 = length
0x08 = AT Command API frame type
0x01 = Frame ID (set to non-zero value)
0x4E4A = AT Command ('NJ')
0xFF = value to set command to
0x5F = Checksum
The checksum is calculated as [0xFF - (0x08 + 0x01 + 0x4E + 0x4A + 0xFF)]
Example: Send an ND command to discover the devices in the PAN. The frame should look like:
0x7E 0x00 0x04 0x08 0x01 0x4E 0x44 0x64
Where 0x0004 = length
0x08 = AT Command API frame type
0x01 = Frame ID (set to non-zero value)
0x4E44 = AT command ('ND')
0x64 = Checksum
The checksum is calculated as [0xFF - (0x08 + 0x01 + 0x4E + 0x44)]
Example: Send a remote command to the coordinator to set AD1/DIO1 as a digital input (D1=3) and apply
changes to force the IO update. The API remote command frame should look like:
0x7E 0x00 0x10 0x17 0x01 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0xFF 0xFE 0x02 0x44 0x31
0x03 0x70
Where
0x10 = length (16 bytes excluding checksum)
0x17 = Remote Command API frame type
0x01 = Frame ID
0x0000000000000000 = Coordinator's address (can be replaced with coordinator's actual 64-bit address if
known)
0xFFFE = 16- bit Destination Address
0x02 = Apply Changes (Remote Command Options)
0x4431 = AT command ('D1')
0x03 = Command Parameter (the parameter could also be sent as 0x0003 or 0x00000003)
0x70 = Checksum
© 2010 Digi International, Inc.
98
DCD [ DIGITAL CORE DESIGN ]
