Using an external potentiometer, factory floor personnel can now precisely calibrate the set points of a motor drive, and program them in whatever units they prefer.

Known as the Accu-Dial, the new potentiometer replaces conventional multi-turn potentiometers, which typically require users to take a seat-of-the-pants approach when characterizing set points on a drive. The new device is said to be ideal for open-loop application on motor-driven conveyor belts, conveyor chains, and assembly lines, as well as on some hydraulic- and pneumatic-based systems.

The unit, designed by engineers at Electro-Sensors, Inc., eliminates the trial-and-error process often associated with calibrating set points with multi-turn potentiometers. "If a potentiometer has no markings on it, and someone tells you to change the setting by two full turns, how do you know if you're getting the desired output?" asks Daniel Bisila, an Electro-Sensors design engineer. "The truth is, you don't know for sure."

The Accu-Dial solves the problem by incorporating a microprocessor and an LCD display that allows users to view the output. Moreover, it lets them program the device in units of their choice. As a result, on a conveyor or transfer line, they can even set it in terms of the number of parts per hour they want the line to produce.

The device is applicable to any drive that sends a voltage ranging from 3.9 to 15V dc to the potentiometer. Since not all drives supply the same voltage, enabling the Accu-Dial to work within those ranges was vital, Bisila says.

To deal with that challenge, Electro-Sensors engineers designed their device to use an A/D converter that compares an analog input from potentiometer's wiper, to the reference voltage applied to the potentiometer. The readout is based on the ratio of those two voltages.

Electro-Sensors engineers say the Accu-Dial is best suited for use with low- to mid-level drives that don't allow users to program the set points. They also stress, however, that it can be used in hydraulic or pneumatic applications. "It's not just for motor drives," Bisila says. "Any application that uses an external potentiometer, and supplies between 3.9 and 15V, can use this device." Electro-Sensors Inc., www.electrosensors.com Enter 576