Digital Potentiometer Quick Start Guide

Introduction

NCD Digital Potentiometer devices allow software control of up to 256 channels of 8-bit digital potentiometers.  NCD manufactures many digital potentiometer devices with a wide range of communication options.  Regardless of device, the command set is generally the same.   This guide is therefore relevant to many product lines, including devices offered exclusively with a USB/RS-232 interface and digital potentiometer outputs, ProXR/UXP expansion devices, and Fusion/UXP expansion devices.  Please note that all Fusion controllers require commands to be wrapped with a header and checksum (please see API Quick Start Guide), which is optional for ProXR series.

Base Station Software (ncd.io/start) allows you to control the outputs of any digital potentiometer.

Shown above, a RS-232 Digital Potentiometer controller with 32 Channel of digital potentiometers.  Many other versions of this device are available, including expansion boards for ProXR UXP and Fusion series controllers.

WARNING:

Potentiometer Outputs Operate in the 0-5VDC Voltage Range ONLY.  Up to 1ma of current may pass through the potentiometer.  NEVER EXCEED 1ma or the potentiometer chip will be damaged.

Hardware Diagram

RS-232 Programmable Potentiometer

RS-232 16-Channel Programmable Potentiometer + XR Expansion Port

Product Code: POT16PROXR

RS-232 Programmable Potentiometer

RS-232 24-Channel Programmable Potentiometer + XR Expansion Port.  Product Code: POT24PROXR

RS-232 Programmable Potentiometer

RS-232 8-Channel Programmable Potentiometer + XR Expansion Port.  Product Code: POT8PROXR

Programmable Potentiometer Expansion Module

16-Channel Programmable Potentiometer Expansion Module.  Product Code: UPOT16

WARNING:

Potentiometer Outputs Operate in the 0-5VDC Voltage Range ONLY.  Up to 1ma of current may pass through the potentiometer. NEVER EXCEED 1ma or the potentiometer chip will be damaged.

Base Station Software

In order to communicate with the Potentiometer, run our Base Station software.

  • Connect the Potentiometer to your computer using your favorite interface technology.
  • Run the NCD Base Station software
  • Select the appropriate COM port or IP Address
  • Click OK.

When the dialog box appears, choose UXP Potentiometer Control Command Set’ as shown in the screen shot below.

To control functions of the Potentiometer:

  1. This option allows you to select which potentiometer you would like to control.  Check the “Select All” box to control all potentiometers simultaneously.
  2. This slider is used to change the resistance of the potentiometer output.
  3. This option stores the power-up default potentiometer values.  This command is NOT supported by all potentiometer devices.
  4. This option loads the power-up default potentiometers and refreshes the potentiometer outputs to the startup values.  This command is NOT supported by all potentiometer devices.
  5. Command dialog box. Reads commands send and device responses in decimal format.

POT Command Set

Potentiometer Control Commands

The POT Command Set is used to control up to 256 channels of potentiometer outputs with 8-bit resolution per channel.  This command set is compatible with all ProXR controllers with a UXP Expansion Port.  This command set may also be used with part numbers that contain the letters POT.

Digital Potentiometers are limited to 1ma of current and have a working voltage from 0 to 5VDC.  Exceeding this working voltage or current may permanently damage the potentiometer chip.

Set a Single Potentiometer

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.

Send Bytes: Byte 1, Byte 2, Byte 3, Byte 4

Function: Command POT Value

Decimal Values: 254, 170, 0-255, 0-255

Hex Values 0xFE, 0xAA, 0x00-0xFF, 0x00-0xFF

Receive Byte:

Decimal: 85

Hex: 0x55

Set All Potentiometers

This command will set all Potentiometers to a specified value where value is the new value of all potentiometers.

Send Bytes: Byte 1, Byte 2, Byte 3

Function: Command Value

Decimal Values: 254, 171, 0-255

Hex Values 0xFE, 0xAB, 0x00-0xFF

Receive Byte:

Decimal: 85

Hex: 0x55

Store a Startup Value for a Specific Potentiometer

This command will store a Startup Value for a specific potentiometer.  Where POT is the potentiometer to store and Value is the value to be stored.  Only the first 32 Potentiometers may be stored by ProXR Enhanced Controllers.

Send Bytes: Byte 1, Byte 2, Byte 3, Byte 4

Function: Command POT Value

Decimal Values: 254, 172, 0-31, 0-255

Hex Values 0xFE, 0xAC, 0x00-0x1F, 0x00-0xFF

Receive Byte:

Decimal: 85

Hex: 0x55

Read the Startup Value for a Specific Potentiometer

This command will read the startup value for a specific potentiometer.  Where POT is the potentiometer to read.  The value will be returned as a number from 0 to 255.

Send Bytes: Byte 1, Byte 2, Byte 3:

Function: Command POT

Decimal Values: 254, 173, 0-31

Hex Values 0xFE, 0xAD, 0x00-0x1F

Receive Byte:

Decimal: 0-255

Hex: 0x00-0xFF

Accessing Port 2 with Fusion Controller

Potentiometer Control Commands

The POT Command Set is used to control up to 256 channels of potentiometer outputs with 8-bit resolution per channel.  This command set is compatible with all ProXR controllers with a UXP Expansion Port.  This command set may also be used with part numbers that contain the letters POT.

Digital Potentiometers are limited to 1ma of current and have a working voltage from 0 to 5VDC.  Exceeding this working voltage or current may permanently damage the potentiometer chip.

Set a Single Potentiometer (Fusion Port 2)

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. This command example accesses Port 2 on the Fusion Series Controllers if available.

Send Bytes: Byte 1, Byte 2, Byte 3, Byte 4, Byte 5

Function: Command POT Value Port 2

Decimal Values: 254, 170, 0-255, 0-255, 2

Hex Values 0xFE, 0xAA, 0x00-0xFF, 0x00-0xFF, 0x02

Receive Byte:

Decimal: 85

Hex: 0x55

Set All Potentiometers (Fusion Port 2)

This command will set all Potentiometers to a specified value where value is the new value of all potentiometers. This command example accesses Port 2 on the Fusion Series Controllers if available.

Send Bytes: Byte 1, Byte 2, Byte 3, Byte 4

Function: Command Value Port 2

Decimal Values: 254, 171, 0-255, 2

Hex Values 0xFE, 0xAB, 0x00-0xFF, 0x02

Receive Byte:

Decimal: 85

Hex: 0x55

Store a Startup Value for a Specific Potentiometer (Fusion Port 2)

This command will store a Startup Value for a specific potentiometer.  Where POT is the potentiometer to store and Value is the value to be stored.  Only the first 32 Potentiometers may be stored by ProXR Enhanced Controllers.  This command example accesses Port 2 on the Fusion Series Controllers if available.

Send Bytes: Byte 1, Byte 2, Byte 3, Byte 4, Byte 5

Function: Command POT Value Port 2

Decimal Values: 254, 172, 0-31, 0-255, 2

Hex Values 0xFE, 0xAC, 0x00-0x1F, 0x00-0xFF, 0x02

Receive Byte:

Decimal: 85

Hex: 0x55

Read the Startup Value for a Specific Potentiometer (Fusion Port 2)

This command will read the startup value for a specific potentiometer.  Where POT is the potentiometer to read.  The value will be returned as a number from 0 to 255.  This command example accesses Port 2 on the Fusion Series Controllers if available.

Send Bytes: Byte 1, Byte 2, Byte 3, Byte 4

Function: Command POT Port 2

Decimal Values: 254, 173, 0-31, 2

Hex Values 0xFE, 0xAD, 0x00-0x1F, 0x02

Receive Byte:

Decimal: 0-255

Hex: 0x00-0xFF