104-QUAD-8 Eight and Four Channel Digital Quadrature Encoder Input Board


  • 4, 6, or 8 channels of quadrature encoder inputs and channel index inputs
  • Counts outputs from up to eight quadrature encoders
  • Three differential channels per encoder, including dual axis and index
  • Input ranges: ±25V and ±7V common mode
  • 4.3MHz maximum clock rate
  • Individual software reset for each channel
  • Standard counting and alarm functions
  • Programmable for counting, speed, and direction; limit setting with interrupts
  • Factory flexible interrupt options


  • RoHS compliant version
Last updated on February 15, 2024, 10:51 am


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PC/104 Digital Quadrature Encoder Input Board

The 104-QUAD-8 card is a general purpose Quadrature Encoder Counter/Interface board. It is provided in the popular 104 format and conditions and monitors the outputs of 8 encoders. I/O connectors are right-angle 34-pin headers.

These functions include anything that can be programmed into the versatile LSI/CSI LS7266R1 integrated circuit. These functions include speed, direction and total count. By providing these functions, it frees the computer for higher level applications.

The ability to provide an interrupt for a parameter, such as total count, further frees the computer from the necessity of constantly reading the position of an encoder.

Interrupts are directed to levels #2 through #7, #10 through #12, and #15 by jumper installation.

The 104-QUAD-8 card is designed for industrial applications. Each input line is buffered and capable of utilizing inputs up to 25 volts. A +5 Volt source is available for appropriate encoders.

The conditioned inputs are connected to LSI/CSI LS7266R1 integrated circuits. These circuits are the heart of the card’s operation. They may be programmed for a variety of functions.

The 104-QUAD-8 occupies 32 bytes of I/O address space. The base address is selectable via jumpers anywhere within the range of 100-3E0 hex. An illustrated setup program is provided with the 104-QUAD-8 card. Interactive displays show locations and proper settings of jumpers to set up board address and interrupt levels.


  • Automatic Test Systems
  • Laboratory Automation
  • Robotics
  • Machine Control
  • Security Systems, Energy Management




Drivers and Downloads

Full list of available Downloads: Software Packages, Drivers, Manuals, and other documents

Information about our Free Software packages:

ACCES is proud to provide a full suite of software support with every Data Acquisition product. We are committed to supporting the most popular operating systems and platforms for our customers. Currently we are actively supporting XP -> 10, both 32 & 64 bit, including “Server 2008,” “Embedded,” and “Compact” flavors for all plug-and-play products including PCI, PCI Express, USB, and more. Many products continue to ship with support for additional operating systems such as DOS, Windows 95, 98, Me, NT4, and 2000.


Among the software we deliver with our products are sample programs in a wide variety of programming languages. These samples are used to demonstrate the software interfaces to our products — and many can be used as-is in your production environments, or to test functionality of the devices out-of-the-box. We’re currently actively supporting sample programs in Microsoft Visual C#, Visual Basic, Delphi, and Visual C/C++, with many devices including samples in Borland C/C++ 3.1 for DOS. Additionally we provide National Instruments LabVIEW compatible DLLs and many demonstration VIs for our devices.


Drivers for various operating systems are also provided, including active support for Windows XP -> 10 — all in both 32-bit and 64-bit flavors, and including consumer, server, and embedded varieties — as well as the 2.6 and newer Linux kernels and recent OSX / macOS versions. Many products continue to ship with driver support for Windows 95, 98, Me, NT4, and Windows 2000, but support for these operating systems is considered deprecated.

Setup Programs and Utilites

Our Data Acquisition devices also include a graphical setup utility that walks you through the process of configuring any option jumpers or switches on the device, as well as explaining a little about the various connectors present.

Many devices also include utility programs – little tools to make your use of the device easier, such as EWriter, a program that allows you to read and write data in the user-accessible EEPROM locations on all our USB data acquisitition products; or WinRISC, a “Really Incredibly Simple Communications” terminal program that lets you get started instantly with serial devices.

“Register Level” Documentation

Besides all this software in all these languages and operating systems ACCES has a policy of open and transparent development: none of our lowest-level “register” interfaces are hidden from you — we document every register in every bus card, every command in every serial board, and every usb control transfer in every USB Data Acquisition board. These lowest-level interfaces allow you to develop for our products in ANY operating system or language, regardless of our actively supporting it or having a driver for it. We have customers actively developing in ADA, Android, Python, Java, MATLAB, Solaris, and more, just by referring to our complete low-level interface documentation! And we provide the full source code to all of our drivers, regardless of operating system, to give you an even bigger head start in your own development tasks.

No Fees or Royalties

All of this software is provided at no additional charge, and is licensed under any of a variety of flexible — and royalty free — options. Check out our software license explanation if you’d like more information.

Custom Software

ACCES also offers Custom Software Services for our products. Our prices are unbelievably low, often as inexpensive as free! If you need something tweaked to support your needs, or an entire enterprise application developed from scratch, it is definitely worth your time to inquire with us, first.

Further information about available ACCES Software:

Redistributing Windows Drivers
A list of ACCES drivers and the files that compose them under different versions of Windows, so you can easily redistribute ACCES cards and drivers.

Power Consumption

  • +5 Volts: 260mA


  • Receiver Type: AM26LS32 provides differential conditioning
  • Configuration: Each Encoder Channel consists of Phase A Input, Phase B Input and Index Input
  • Number of Channels: 8
  • Common mode input range: ±7 V maximum
  • Differential Input Range: ±7 V typical
  • Input Sensitivity: ±200 mV
  • Input Hysteresis: 50 mV Typical
  • Absolute maximum input differential: ±25 V
  • Single Ended Input Range: +1.6 to +7 V for high, -7 to +1.2 V for low


  • Counter Type: LS7266R1 24 bit Dual Axis Quadrature Counter
  • Quadrature Input Frequency: 4.3 MHz maximum
  • Separation: 57 ns min
  • Input A or B High Pulse Width: 115 ns min
  • Index Pulse width: 85 ns min
  • Non Quadrature Input Frequency: 30 MHz maximum
  • Input A: high pulse width 16 ns min
  • Filter Clock (FCK): Same as Bus Clock (normally 8.33 MHz), Optional Crystal available (33MHz)
  • Digital Filter rate: Same as FCK

Interrupt Controller

  • Controller Type: CPLD
  • Interrupts: Jumper Selectable (2-7, 10-12, 15)
  • Interrupt Sources: All Carry/Borrow outputs from LS7266R1s
    All Index Inputs
  • Addressing: ISA bus address is set by jumpers


  • Operating Temperature: 0°C to +70°C (Optional -40°C to +85°C)
  • Storage Temperature: -50°C to +120°C
  • Humidity: up to 95% RH, non-condensing

CE testing & approval must be done at the system level, in the designed enclosure, and is not done on individual boards.

ModelDescriptionPrice (USD)

8-Channel PC/104 Digital Quadrature Encoder Input Board


6-Channel PC/104 Digital Quadrature Encoder Input Board


4-Channel PC/104 Digital Quadrature Encoder Input Board

STB-34 Screw terminal board, 34-pin connector $44
C104-34F-12 Ribbon cable, DB34 Female to Female, 12″ $12
Model Options (call for pricing)
-RoHS RoHS-compliant version