IEEE-488: A digital data communications standard popular in instrumentation electronics. This parallel interface is also known as GPIB, or General Purpose Interface Bus.

Impedance: The combination of AC and DC resistance in a circuit, measured in ohms.

Incremental Motion: A motion control term that describes a device that produces one step of motion for each step command (usually a pulse) received.

IncrementalProgramming: A coordinate system where positions or distance are specified relative to the current position.

Inertia: A measure of an object's resistance to a change in velocity. The larger an object's inertia, the larger the torque accelerate or decelerate it. Inertia is a function of an object's mass and its shape.

Inertia Match: For most efficient operation, the system coupling ratio should be selected so that the reflected inertia of the load is equal to the rotor inertia of the motor.

Indexer: Electronics which converts higj level motion commands from a host computer, PLC or operator panel in to step and direction pulse stream for use by the step motor driver. Indexec can be broadly divided into two classes. A preset indexer typically accepts distance, velocity and ramp time inputs only. the more sophisticated programmable indexer is capable of complex motion control and includes program memory.

Inductance: The electrical equivalent to mechanical inertia, that is the property of a circuit which has tendency to resist current flow when no current is flowing and when current is flowing has tendency to maintain that current flow. Poewrtec, measures inductance (line-to-line) with a bridge at 1000Hz and with the rotor positioned so the back-EMF waveform is at the peak of the sinusoid.

Insulator: A material that blocks the flow of current which is used for short circuit and shock prevention.

I/O: Abbreviation of input/output. Refers to input signals from switches or sensors and output signals to relays, solenoids etc.