A programmable data link module is used on a time division multiplex data bus. The module receives data from the data bus during a selected time slot for a selected number of frames. The data link module includes an input circuit for generating a data output signal data to the data bus in response to input signals from an input device coupled to the module. The input circuit includes a programmable input voltage level selector, allowing different voltage rated input devices to be used with the data link module. A hysteresis circuit sets a minimum voltage level threshold representative of the input device being in one logic state and a maximum voltage level threshold representative of the input device being in another logic state.