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What Is a Stepper Motor Indexer?

Alex Newth
Alex Newth

A stepper motor is a computer-controlled motor that divides one full motor rotation into many different steps. The reason for these many steps, and for the motor being controlled by a computer, is that a stepper motor is made to be very accurate, so the user can tell it to perform an exact amount of steps or rotations. There are many parts to a stepper motor, and the stepper motor indexer is part of the motor’s control system. The stepper motor indexer is responsible for clocking the motor and providing directional pulses. Without the indexer, the motor would not know which way to turn or how many steps to make.

When a step motor is employed for use in any industry or to fulfill any need, it starts with the computer or a microprocessor. The user enters information, in code, about what direction he or she wants the step motor to move, how many steps, and the motor’s speed. The coding for the stepper motor depends on the computer or microprocessor used, along with the step motor itself.


After the instructions are finished, they travel from the controller into the stepper motor indexer. Here, the stepper motor indexer interprets the code and translates it into actual pulses and directions. Those directions then feed into the driver and immediately into the step motor to perform the instructed movement.

The indexer itself is responsible for two main aspects of the step motor movement: direction and clock pulses. A stepper motor moves based on electrical pulses, so the motor has to have the correct electrical signals to move in the right direction. The stepper motor indexer tells the motor what electrical pulse is needed for the motor to move according to the user’s needs.

The term "clock pulses" refers to how many steps the motor creates and how much energy is fed into the motor as a whole for it to move the appropriate number of steps. If the clock pulse is set incorrectly, or not interpreted accurately by the indexer, the motor may move too much or too little. This can potentially ruin an experiment or function, which is why the indexer must be able to interpret the user’s commands without fail.

Along with movement, another important function of the stepper motor indexer is to have a stop function. When running an experiment, the person who programmed the step motor may have set the speed or steps too high. To keep the motor from being damaged, the user must issue a stop command into the indexer so the motor ceases movement.

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