A communications system is provided in which a host may receive data from a slave device over a polling bus. The slave device first reports to the host an initial amount of data to be transferred. The host can then initiate a data transfer from the slave device in order to retrieve the specified amount of data. As that initial data is being transferred over the bus, if additional data to be transferred to the host is received by the slave device, the slave device will report that supplemental amount of data to the host along with the initial data. The host may then immediately schedule a supplemental data transfer from the slave device in order to retrieve the additional data. The slave device may utilize a self-decrementing counter in order to keep track of the packets that require transfer but have not yet been reported to the host. The amount of data reported by the slave device to the host device may be provided as a count of packets in which the packets have a predetermined maximum size.