Xbee API frame is processed locally. Only RF data is passed through air? What does it mean??

XBee & XBee Gateway XBee - 802.15.4
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1

Related to article http://knowledge.digi.com/articles/Knowledge_Base_Article/Escaped-Characters-and-API-Mode-2
in knowledge base

What are the contents of RF data? and How is API frame processed at the transmitting and the receiving end if both side Xbee series 1 radios are configured to work in API mode 2.

2

API mode only affects the data going in and out of the UART of a local node. That is the node that is in API mode.

Data sent over the air consists of the the Data Destination Address provided in the API frame and the Data Payload.

On the receiving side, the RF buffer receives the RF packet and verifies the address. If the address is for that node and the Checksum is valid, the data payload portion is sent to the radios UART buffer and out the data out Pin.

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3

Suppose we send an API mode 2 TX 16 frame to DIN pin of Xbee, suppose its 7E 00 07 01 01 AB 10 00 09 7D 33 26
Start Delimiter----------- : 7E
Length--------------------- : 00 07
Frame Type--------------- : 01
Frame ID------------------ : 01
Dest Addr 16bit--------- : AB 10
Options-------------------- : 00
RF Data (Not escaped) : 09 13
RF Data (Escaped)----- : 09 7D 33
Check-sum-------------- : 26

Do you mean to say the Dest addr 16 bit and the RF data(Not Escaped) will be transmitted by Xbee Transmitter over air.

4

Yes, but depending on if the receiving module is in API mode or not on if the Source address will be provided out the UART with the data or just the data payload.

5

Ok.
But we are transmitting Dest addr 16 bit and rf data, then how does the receiver get the information about the source address. Or is there more to it than that.

6

The Source address is included in the RF packet over the air along with the PAN ID.

7

So can it be concluded as follows :
TX16 API mode 2 frame is passed to Xbee through UART.
Its stored in DIN buffer. If Xbee is in API mode , The Xbee processor will validate the TX Frame check-sum and send the Destination Address as well as data to RF TX Buffer.
The data from this buffer will leave as RF packet which contains the source address as well as destination address.

The Xbee receiver at the other end receives this RF packet and stores it in RF RX Buffer. if this Xbee is in API mode, the processor takes the source address and data from this buffer and sends it to DOUT buffer. The Data comes out of the UART module as API RX Frame.

8

Yes that looks close enough.