Embodiments of the present disclosure provide a protective circuit to be used in a digital output module, the digital output module comprises a first voltage source and at least an output terminal. The protective circuit comprises: a first sampling unit for sampling a first voltage relevant to the output current from the first voltage source, a first comparing unit for comparing the sampled first voltage with a first reference voltage, a control unit for generating a current regulating signal based on a result from the first comparing unit, and a current regulating unit for regulating the output current from the first voltage source based on the current regulating signal. This protective circuit provides overflowing and short circuit protection, and is cheap in cost.