Transmit mode

Prior to transmitting data, the module ensures that a 16-bit network address and route to the destination node have been established.

If a 16-bit network address is not provided, a Network Address Discovery takes place. In order for data to be sent, a route discovery takes place for the purpose of establishing a route to the destination node. If a device with a matching network address is not discovered, it discards the packet. The device transmits the data once a route is established. If route discovery fails to establish a route, the device discards the packet. The following diagram shows the Transmit Mode sequence.

When Zigbee data is transmitted from one node to another, the destination node transmits a network-level acknowledgment back across the established route to the source node. This acknowledgment packet indicates to the source node that the destination node received the data packet. If the source node does not receive a network acknowledgment, it retransmits the data.

It is possible in rare circumstances for the destination to receive a data packet, but for the source to not receive the network acknowledgment. In this case, the source retransmits the data, which can cause the destination to receive the same data packet multiple times. The XBee modules do not filter out duplicate packets. We recommend that the application includes provisions to address this issue.

For more information, see Transmission, addressing, and routing.