8-Channel Programmable Potentiometer with USB Interface

Programmable Potentiometer

"Electronic Resistance Control Through Simple Commands"

Digital Potentiomer

Replace manual potentiometer adjustments with software control. NCD's Programmable Digital Potentiometer allows your application to electronically adjust resistance values by simply sending commands from a computer, PLC, microcontroller, or custom software.

Each controller provides 8 independent digital potentiometers with 256 programmable tap positions per channel and is available in 10kΩ, 50kΩ, and 100kΩ versions. Individual channels can be adjusted independently or multiple channels can be updated simultaneously using the same simple command set used throughout the ProXR product family.

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How It Works

Each potentiometer provides three terminals: A, Wiper, and B.

Sending a lower value moves the wiper toward terminal A, decreasing the resistance between A and the wiper while increasing the resistance between he wiper and B.

Sending a higher value moves the wiper toward terminal B, decreasing the resistance between the wiper and B while increasing the resistance between A and the wiper.

The first 32 potentiometer channels can store a programmable startup position, allowing your application to automatically restore critical resistance values after power is applied.

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Choosing the Right Resistance Value

Digital potentiometers are available in 10kΩ, 50kΩ, and 100kΩ versions. The resistance value you select should match the requirements of the circuit you are replacing or designing.

• 10kΩ is the most common choice and works well for many signal conditioning, amplifier, and general-purpose control applications.
• 50kΩ is often selected when a higher resistance range is needed while maintaining moderate current flow.
• 100kΩ is best suited for high-impedance circuits where very little current is required.

If you are replacing a traditional potentiometer, simply choose the digital potentiometer with the same resistance value. The programmable tap positions provide 256 adjustable resistance settings across the selected range.

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Software Controlled Resistance

Adjust one potentiometer or every potentiometer with simple serial commands. The POT Command Set provides precise electronic control over resistance values without manual adjustment.

Whether controlling a single channel or a fully expanded system, the command structure remains consistent, making it easy to integrate with custom software, automation systems, PLCs, and NCD Base Station Software.

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Expand as Your Application Grows

Built on NCD's proven ProXR platform, the controller is designed to grow with your application.

The integrated UXP Expansion Port supports expansion up to 256 programmable potentiometers, while the XR Expansion Port allows NCD relay expansion boards to be added to the same system. This makes it possible to combine programmable resistance control and relay control using a single controller architecture.

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The ProXR Command Set

Simple Serial Commands. Serious Control.

The ProXR family of controllers is driven by a powerful, low-level serial command set. You send a short numeric or Hex command to the board - and the board responds immediately.

This design keeps your software fast, reliable, and easy to integrate into almost any platform, from small scripts to full automation systems.

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How to Send Commands

All ProXR controllers operate using a small sequence of bytes sent over a serial connection.

You can send commands as:

• Decimal byte values
• Hex byte values

Both formats perform the exact same operations - choose whichever format your software or controller prefers.

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What a Command Looks Like

This command will set a single Potentiometer to a specified value where POT is the channel number and value is the new value of the potentiometer:
254 170 0-255(Channel Number) 0-255(Value) - Set specific POTs value
0xFE 0xAA 0x00-0xFF 0x00-0xFF - If you require Hex

The controller processes the command and returns a confirmation byte 85 (0x55 Hex) when the operation completes.

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Base Station Compatible

NCD's Base Station Software provides a simple point-and-click interface for learning the command structure, testing communications, and controlling potentiometer outputs before writing software.

It is an excellent development tool for evaluating hardware and generating the commands used in your own applications.

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5-Yeary Warranty & Guarantee

Every potentiometer is covered by:

• 5-Year Functional Warranty
• 30-Day Money-Back Guarantee

If you're not satisfied, send it back for a refund within 30 days. (Damage caused after delivery isn't covered.)

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Essential Power Requirements

Clean, regulated power is critical.
A stable 12VDC supply ensures both the inputs and onboard firmware operate correctly. Unstable or noisy power can cause improper reading or communication issues.
We recommend the PWR12-US (120VAC → 12VDC @ 1.25A) or our international supply with interchangeable adapters.
Learn More

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Shipping

All boards ship directly from our Missouri facility. Each unit is built and tested at the time of order - please allow 3 - 5 days for production. We ship primarily through UPS, but we're happy to use FedEx or DHL for international orders when you provide your account number. Questions? Call us at 800-960-4287 or email sales@relaypros.com.

USB Relay Control

"Send commands via your computer's USB port"

Mounts as a Virtual COM Port

The USB Relay connects directly to your computer's USB port and appears as a standard COM port. On Windows machines with internet access, the correct FTDI drivers install automatically.

Once powered, the board listens for compact serial commands - typically 2 - 6 bytes. After processing your command, it returns ASCII code 85 to confirm successful completion.

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USB Communications Module

The USB Relay module makes controlling relays simple. Plug it into any available USB port and begin sending standard serial commands to switch relays or read A/D inputs.

Every NCD USB interface uses a genuine FTDI FT232-RL USB-to-Serial converter chip for maximum stability and cross-platform support. With drivers available for Windows, macOS, Linux, and more, the module communicates using a Virtual COM Port for easy software integration.

Once installed, open the COM port at 115.2K baud and start exchanging data immediately. On-board USB, TX, and RX LEDs provide live communication feedback. The module uses a durable USB Mini connector - our preferred interface for longevity and reliability.

Simply download the latest Base Station Software, install it on your Windows PC, and your COM port will appear automatically, ready for communication.

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Virtual COM Port

A Virtual COM Port (VCP) registers as a standard serial port on your computer, allowing you to use new or existing serial-based software with any NCD Industrial controller.

Because VCP communication is one of the easiest and most universally supported communication formats across operating systems, languages, and hardware platforms, the ZUSB USB Interface is the ideal tool for learning, testing, and operating NCD devices.

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Induction Considerations

For most applications, the onboard capacitors provide more than enough suppression, and users will never encounter communication issues.

However, switching inductive loads such as motors can create higher levels of electrical noise, and in those situations additional precautions may be necessary. Testing is recommended for motor-based installations to ensure reliable communication.

If communication problems do occur in these high-induction environments:

• An RS-232 communications module provides a more noise-resistant interface.
• When USB connectivity is still needed, a USB-to-RS-232 adapter paired with the RS-232 module offers the stability of RS-232 with the convenience of USB.
• RS-232 naturally blocks induction to safer levels, allowing the adapter to operate without errors even in demanding motor-control setups.

For all other users and non-motor applications, standard USB operation typically performs without complications.

The XR Expansion Port

"Running out of relays? Just plug in more!"

Add Relays as Your Needs Grow

ProXR Controllers were built with relay expansion in mind. The XR Expansion Port lets you add banks of external relays to any ProXR or Taralist board equipped with an XR Expansion port. Expansion boards can be added at any time as your system grows, up to a maximum of 256 total relays.

As expansion boards are added, additional relay banks become available automatically. Simply add another expansion board whenever you need more relays.

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Relay Banks - How Large Systems Stay Simple

ProXR and ProXR Lite controllers organize relays into groups of eight called banks.

Each bank contains:

• Relay 1 through Relay 8

Expandable ProXR boards can add additional banks using XR expansion boards as your system grows.

For example:

• An 8-relay controller uses one bank
• A 32-relay controller uses four banks
• A 64-relay setup uses eight banks

Instead of creating a different command for every relay in a large system, the ProXR firmware lets you:

• Select a bank
• Send simple relay commands within that bank

This keeps the command structure fast, compact, and easy to manage - from a single-bank ProXR Lite installation to large, multi-bank ProXR expansion systems. From a single 8-relay board to a fully expanded 256-relay system, the command structure does not change.

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Linking XR Expansion Boards Together

XR Expansion Boards include both an XR Input and XR Output connector. Connect the XR Output on your ProXR controller to the XR Input on the first expansion board. To add more relays, connect the XR Output of one expansion board to the XR Input of the next board in the chain.

You can mix and match different relay types on expansion boards to match your application. A 6" expansion cable is included with each expansion board.

For best reliability, keep all expansion cabling as short as possible. Maximum expansion length and total relay count depend on your installation, electrical noise, and overall cable length. For best compatibility, the combined length of the controller, expansion boards, and cables should not exceed 1-2 meters.

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Mix & Match

Expansion boards do not need to match the relay type or amperage of the main controller or other expansion boards. Mix and match expansion boards to get the exact relay types and current ratings your application requires.

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Will Not Operate Independently

This Expansion Board gets it's commands from the main ProXR, Taralist or Potentiometer board and will not operate independently.  This board MUST be plugged into a ProXR or Taralist board to operate and will not function on it's own.

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Essential Power Requirements

All XR expansion boards require their own 12 VDC power source. A regulated 12 VDC supply must be connected directly to each expansion board for proper operation.

We offer a compatible wall-plug power supply at checkout, or you may use your own regulated 12 VDC supply. Learn More

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Maximum Relay Rating Notes

ProXR is capable of expanding to an absolute maximum of 256 Relays.  In some cases, it may not be possible to control all 256 relays, particularly in applications where high noise levels may be involved.  Experimentation may be required, as it is not possible for us to guarantee all users will be able to utilize all 256 relays in every application.  Noise tends to accumulate when several expansions are connected together.  For best results, the XR expansion cables must be as short as possible.

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RoHS Compliant

Expansion boards are led free and RoHS Compliant.  If your requirements are for RoHS compliant parts every expansion board is manufactured with RoHS compliant led free parts and solder.

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2-Million Cycles

XR Expansion Boards are designed for long life just as the ProXR boards, you should expect to get years of service from expansion board and literally 2-million cycles from the relays on board.  With a 5-year warranty and a money back guarantee add more relays anytime the need arises!

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Accessories

Data Sheets & Quick Start Guides

Below are the Data Sheets Quick Start Guides for this board.  These are the guides that will help you communicate and configure this board.