TDMA communications between a host device and a number of clients on a communications channel are dynamically adapted to allocate or de-allocate time slots in response to changes in the number of active clients. The system initially operates in a startup mode in which the host device transmits a startup message on the communications channel and assigns a timeslot in a TDMA cycle in response to connection requests received from each of the requesting clients. After exiting the startup mode, the system operates in a normal mode in which the host device initiates the TDMA cycle by transmitting a polling message on the communications channel that indicates a number of timeslots occurring within that particular TDMA cycle. The host changes the number of timeslots indicated in the polling message to responsively adapt duration of the TDMA cycle as the number of clients communicating via the communications channel changes.