Computer Controlled Potentiometer Outputs

256 Levels of Programmable Resistance Outputs
Potentiometers are available in 10K, 50K, and 100K values
Highly Reliable Board Design For Demanding Applications


USB Digital Resistor

A potentiometer is a variable resistor, capable of changing resistance under software control. Programmable potentiometers are ideal for making computer controlled mixers and audio/video mixing devices, as well as light dimmers and motor speed controllers. The POT and UPOT series controllers offer RS-232 and USB controlled potentiometers, and are ideally suited for integration into various types of test instruments, programmable amplifiers, programmable power supplies, and anything else that can benefit by software controlled resistance variation. As a general rule, potentiometer devices often require external circuitry. For instance, it is not possible to control the brightness of a light bulb directly or the speed of a motor without some additional electronics.

Our POT Series controllers offer our customers the capability of integrating programmable digital potentiometers into their next computer control application.  Potentiometer controllers are available with 10K, 50K and 100K programmable potentiometers. It is possible to set the power-up default state of the first 48 potentiometers. It is also possible to control each potentiometer in 256 steps, allowing fine adjustments under software control. You can control up to 256 potentiometers under software control using additional UPOT16 expansion modules, you can control each individually or all simultaneously. In addition to potentiometer control the POT and UPOT series controllers include the ProXR command set, allowing you to plug in up to 256 relays into the expansion port.

This device offers a USB interface that mounts as a Virtual COM Port under ANY Operating System, and is controlled at 115.2K Baud. This device also includes a XR expansion port, allowing you to control relays by plugging in XR expansion boards.

Resistance Output

Please keep in mind; our POT series controllers offer a resistance output, and cannot provide a voltage output of any kind without additional electronics. The potentiometers are limited to applications that operate in the 0 to 5V range. Each potentiometer has a maximum current capacity of 1ma. Exceeding these ratings will immediately damage the controller.

Potentiometers have 3 Connections: A, Wiper, and B. When a low value is sent to the controller, the wiper moves closer to A, decreasing the resistance between A and the wiper (increasing the resistance between the wiper and B). When a high value is sent to the controller, the wiper moves closer to B, decreasing the resistance between the wiper and B (increasing the resistance between the wiper and A). The first 48 channels of wiper values can be set to a power-up default state. It is possible to set the wipers on all outputs individually or simultaneously. 

You can send commands to program the output resistance of each individual output, or you program all outputs at the same time.  Other commands allow you to set the startup resistance of each output.   The ProXR command set allows you to send commands to activate relays, deactivate relays, control all the relays at one time, plus you can send commands that tell a relay to turn on for a few seconds, minutes, or hours.  You can assign 16 timers to any of the 256 relays, and set the timers to go off after the duration has expired.  The complete command set can be found on page 43 of the ProXR Manual.

ProXR Command Set

If you are new to our products,  we would like to introduce to you is a term we call "ProXR".  ProXR refers to a set of standardized commands used for computer control and data collection.  A controller that supports the ProXR command set is a controller that is built to control up to 256 relays, using commands that can be sent to any controller that offers ProXR compatibility.  This allows software developers to create programs for our products, then upgrade or change connectivity options without having to rewrite their software.

Add relays to the potentiometer or add potentiometers to the relay board, either way you look at it adding potentiometers to relay control is easy. In the above photo we are adding relays to the UPOT24ProXR potentiometer (bottom right) by connecting to an XR241DPDT controller above.  It is also connected to a UPOT16 Expansion Module (bottom left) to provide an additional 16 potentiometers.

12VDC Power Supply Required

This ProXR series potentiometers offers RS-232 or USB communications, requiring only a 12VDC Power Supply.  Once powered up, the controller waits for a command.  A command consists of a few bytes of data.  Usually between 2 and 6 bytes.  Once the command has been received, the controller processes the command, and sends you back ASCII character code 85 to signal the completion of your command.

The features list of the ProXR series controllers is extensive.  Our ProXR Software helps get you acquainted with the powerful command set.