Digi XBEE-PRO S3B Manual

XBee‐PRO®900HP/XBee‐PRO®XSCRFModules
©2014DigiInternationalInc. 58
6.XBee‐PRO900HPAPIOperation
As an alternative to Transparent Operation, API (Application Programming Interface) Operations are available.
API operation requires that communication with the module be done through a structured interface (data is
communicated in frames in a defined order). The API specifies how commands, command responses and
module status messages are sent and received from the module using a serial data frame.
Please note that Digi may add new frame types to future versions of firmware, so please build into your
software interface the ability to filter out additional API frames with unknown Frame Types.
API Frame Format
Two API modes are supported and both can be enabled using the AP (API Enable) command. Use the following
AP parameter values to configure the module to operate in a particular mode:
•AP = 1: API Operation
• AP = 2: API Operation (with escaped characters--possible on UART only)
API Operation (AP parameter = 1)
When this API mode is enabled (AP = 1), the serial data frame structure is defined as follows:
Figure6‐01. SerialDataFrameStructure:
MSB=MostSignificantByte,LSB=LeastSignificantByte
Any data received prior to the start delimiter is silently discarded. If the frame is not received correctly or if
the checksum fails, the module will reply with a module status frame indicating the nature of the failure.
API Operation - with Escape Characters (AP parameter = 2)
When this API mode is enabled (AP = 2), the UART data frame structure is defined as follows:
UARTDataFrameStructure‐withescapecontrolcharacters:
MSB=MostSignificantByte,LSB=LeastSignificantByte
Escape characters. When sending or receiving a UART data frame, specific data values must be escaped
(flagged) so they do not interfere with the data frame sequencing. To escape an interfering data byte, insert
0x7D and follow it with the byte to be escaped XOR’d with 0x20.
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
Start Delimiter
(Byte 1)
Length
(Bytes 2-3)
Frame Data
(Bytes 4-n)
Checksum
(Byte n + 1)
0x7E MSB LSB API-specific Structure 1 Byte
Characters Escaped If Needed

Digi XBEE-PRO S3B Specifications

General

Brand	Digi
Model	XBEE-PRO S3B
Category	Control Unit
Language	English