Back channel data provides a mechanism for the hub application to send data to the node at the request of the node. The node is responsible for interrogating the hub for back channel data as part of a forward data packet. The node starts by setting the BCDR bit in the data header. If the packet is successfully acknowledged by the hub then the node enters receive mode with the node network parameters then waits for n ms trying to receive from the hub. In the case of a wall powered hub, the hub can transmit a back channel data packet immediately without waiting for a request from the node.