Setup: Xbee S2 with API mode
Is there a way to send a proper unicast Tx by using only a 16-bit address?
(64-bit address unknown, unavailable or simply one does not care about it)
Official manual (excerpts below) leads to understanding
(especially Transmit Mode Sequence diagram on page 31)
that one only needs a 16-bit address to send a packet,
whereas 64-bit address is used to discover 16-bit address when not known in advance.
Problem is that when one knows only 16-bit address (e.g. discovered by MP) and want to send a unicast Tx,
64-bit address field still needs to be set.
(supported options: 0x00 00 (coordinator), 0xFF FF (broadcast), or exact address of a destination)
(N.B. 0x FF FE (unknown) is not supported like for 16-bit addresses)
Funny enough, I can put my money that Address Table can resolve a 16-bit address to a 64-bit one
since it contains both of them (it is populated on ND, join, etc).
Any thoughts would be appreciated.
All ZigBee transmissions are sent using the source and destination 16-bit addresses.
The routing tables on ZigBee devices also use 16-bit addresses to determine how to route data packets through the network.
However, since the 16-bit address is not static, it is not a reliable way to identify a device.
To solve this problem, the 64-bit destination address is often included in data transmissions to guarantee data isdelivered to the correct destination.
The ZigBee stack can discover the 16-bit address, if unknown, before transmitting data to a remote.
When sending a unicast transmission, the ZigBee network layer uses the 16-bit address of the destination and each hop to route the data packet.
If the 16-bit address of the destination is not known, the ZigBee stack includes a discovery provision to automatically discover the destination device's 16-bit address before routing the data.
The application can then send both the 16-bit and 64-bit addresses to the XBee in the API transmit frames which will significantly reduce the number of 16-bit address discoveries and greatly improve data throughput.
Each entry in the address table should contain a 64-bit destination address and its last known 16-bit address.
ZigBee Transmit Request
The 64-bit destination address should be set to 0x000000000000FFFF for a broadcast transmission (to all devices).
The coordinator can be addressed by either setting the 64-bit address to all 0x00s and the 16-bit address to 0xFFFE, OR by setting the 64-bit address to the coordinator's 64-bit address and the 16-bit address to 0x0000.
For all other transmissions, setting the 16-bit address to the correct 16-bit address can help improve performance when transmitting to multiple destinations. If a 16-bit address is not known, this field should be set to 0xFFFE (unknown).