In mode 3, it is important to note that the output pattern is retained. That is, the last state is present on the outputs and all pulses are ignored. Thus, the coils of the motor are energized and the motor is held in position. The potential disadvantage in doing this is illustrated with a simple example. Assume a stepper is being used to lift and lower an object.
Enable high is used, the only thing holding the object is a slight residual magnetism in the motor.
Enable high, the object will fall. Of course, this depends on the application. Control of Multiple Stepping Motors. The state of decoder inputs A2, A1 and A0 determines which of the decoder outputs goes to logic zero. When low, the decoder is enabled and the output corresponding to the address on A2, A1 and A0 goes low.