PC/104 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 Available. Please contact us for ordering information


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

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.

Drivers and Downloads

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

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.

Available Reference Manuals

Available Software Downloads

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: ±25 V maximum
  • Input Sensitivity: ±200 mV
  • Input Hysteresis: 50 mV Typical
  • Absolute maximum input differential: ±25 V


  • 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.

ModelPrice (USD)

Acquisition, Control, Communication: Engineering and Systems

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