Multifunction analog/digital I/O | Model 826

Model 826 Multifunction analog/digital I/OView CE compliance report
  • Six 32-bit counters support incremental encoders, PWM/pulse generation & frequency/period/pulse measurement
  • 16 differential analog inputs, 16-bit, 300 ks/s
  • 8 analog outputs, 16-bit, 900 ks/s
  • 48 digital I/Os with edge detection
  • Multistage watchdog timer with final-stage relay
  • Fail-safe output controller
  • Board ID switches for easy device identification


Play video 826_introductionWatch the video

Sensoray's model 826 is a versatile analog and digital I/O system on a PCI Express board. It has 48 digital I/Os with edge detection, sixteen 16-bit analog inputs, eight 16-bit analog outputs, six 32-bit counters with quadrature clock decoders, a watchdog timer with fail-safe controller, and a flexible signal router. A board ID switch is provided to allow multiple 826 boards to easily coexist on a backplane. The board's high performance, compact size, and abundant resources make it ideally suited for a wide range of measurement and control applications including robotics, scientific instruments, CMM and CNC machines, control loaders, motion platforms, factory automation, and packaging and conveyor equipment.

826 block diagram



Free Linux and Windows software development kits are available for model 826 (click the Downloads tab above). The SDKs include a high-level application program interface that provides thread-safe access to the board's hardware resources. The API supports both polled and event-driven operation to facilitate any strategy of single- or multi-threaded programming. Hardware states are preserved when the API starts and terminates, which allows unconflicted, concurrent access by multiple processes and graceful, non-disruptive warm starts.

Experienced programmers will appreciate the API's use of high-performance blocking functions (vs. inconvenient callbacks) for event handling, which seamlessly manage interrupts while eliminating the grunt work of I/O programming. Pre-built API libraries are included, and the generic, open-source API is designed to reliably work with and easily port to real-time operating systems. Comprehensive documentation and source code examples in C and VB.NET are provided to accelerate software development, and a VI is available for Labview developers.

Connectors and cables

Low-profile headers and flat cables (not included) are used to connect I/O signals to external circuitry, enabling the board to easily fit into high-density systems while still allowing the use of popular IDC cables and connectors. The board's mounting bracket employs a built-in cable clamp to keep wires organized and secure. Sensoray offers a variety of cables and breakouts for connecting the board to field wiring; click the Accessories tab above for details.

Board mounting bracket with integrated cable clamp

Board mounting bracket with integrated cable clampBoard mounting bracket with integrated cable clamp


Each 32-bit counter can independently perform popular functions such as incremental encoder interface, frequency counter, pulse/PWM generator, and pulse width/period measurement. The flexible architecture enables a diverse range of applications, including two-signal edge separation measurement, retriggerable and non-retriggerable one-shots, and precise, hardware-timed program delays.

Incremental shaft encoders and linear encoders are supported by high-performance quadrature clock decoders and a versatile sampling system, allowing the board to serve as a complete 6-axis motion interface. Multiple, concurrent triggers are available to accommodate applications such as periodic sampling for motion control feedback, simultaneous multi-channel sampling (e.g., for touch-trigger probes), or both at the same time.

For demanding real-time applications, every counter includes a 16-deep event FIFO that simultaneously captures timestamp and trigger information along with counts — at rates up to 50 million events per second — so that important events will never be missed. High-resolution timestamps (1 µs) ensure precise measurement of time-critical phenomena such as incremental encoder speed and position.

1 of 6 counter channels


Dedicated clock and index input pins accept both differential RS-422 and single-ended TTL signals, and the software-controlled signal router can be used to connect a counter's I/O signals to digital I/Os and other counters. Programmable filters are provided to eliminate noise and glitches from input signals.

Analog I/O

Analog inputs can be independently configured for ±1V, ±2V, ±5V, or ±10V measurement ranges. When triggered, a burst of up to sixteen samples is acquired. Conversion bursts can be software or hardware triggered, or the controller can continuously perform back-to-back bursts.

Analog input system


The eight analog outputs can be independently configured for 0 to +5V, 0 to +10V, ±5V, or ±10V output ranges. All analog circuitry employs fully electronic calibration, with factory-programmed calibration data stored on-board to allow boards to be easily and quickly installed.

Digital I/O

Each open-drain digital I/O (DIO) can operate as an input or output, or implement active low wired-OR or active high wired-AND functions. Input edge detection is supported on all channels, and input filters are available for contact debouncing and noise/glitch suppression. For maximum flexibility, the API allows any program thread to block while waiting for edge events within an arbitrary set of channels.

1 of 48 DIO channels


Standard 50-pin headers are used to connect the DIOs to Sensoray breakout boards or solid-state relay (SSR) racks, or to custom signal distribution systems. Special circuitry ensures that when the 826 is unpowered, its DIOs will not energize SSRs on externally powered racks — a hazardous behavior commonly found in other I/O boards.

Watchdog Timer

The three-stage watchdog timer can initiate a sequence of actions according to user-defined timing. Various types of actions can be triggered, including fail-safe activation, generating interrupt requests, and energizing the on-board solid state relay to invoke a system reset or signal other external circuitry.

Fail-safe Controller

The board's fail-safe controller can force analog and digital outputs to predetermined, configurable "safe" levels in response to a watchdog or external trigger. The controller can work in concert with the watchdog timer and external devices, such as E-stop (emergency stop) and safety interlock contacts, to automatically switch output signals to safe levels without software intervention.


26-pin breakout board

Model 7503TDIN breaks out signals from three counter channels. It connects to the 826 with an 826C1 cable. Two 7503TDINs can be used to break out all six counter channels.

7503TDIN — DIN rail mountable, 26 conductor breakout board

7503TDIN breakout board

50-pin breakout board

Model 7505TDIN breaks out the 826's analog or digital I/O (DIO) signals. It connects to the 826 with an 826C2 cable. One 7505TDIN will break out all of the analog signals, or 24 of the 48 DIO signals. Three 7505TDINs can be used to break out all analog and DIO signals.

7505TDIN — DIN rail mountable, 50 conductor breakout board

7505TDIN breakout board

Solid-state relays

Model 7501T8 connects eight DIO signals to solid state relays (SSRs). It has sockets for any combination of type G4 SSRs (AC or DC, input or output). It connects to the 826 with an 826C2 cable.

7501T8 — panel mountable, 8 solid state relay board

7501T8 SSR rack, connected to an 826 board



Two cables are available for connecting the 826 to external circuitry. Both have a low profile connector at one end that plugs into the 826 board. The other end has a standard IDC male connector with 0.1-inch pin spacing. Standard cable length is 24 inches; please call if you need a custom length.

  • Cable type 826C1 connects up to three counter channels; two cables are needed if four or more counters are used.
  • Cable type 826C2 connects either all analog signals or 24 digital I/Os; three cables are needed if all analog and digital I/Os are used.


Digital I/O
Channels48 bi-directional, open drain, TTL/5VCMOS compatible
Internal pull-up resistor10 KΩ, 5%
Output low-level current 24 mA max.
Output low-level voltage0.6 V max. @ 12 mA
0.8 V max. @ 24 mA
Input voltage range ¹0 to +5.5 V (-0.5 to +6.5 V absolute max.)
Input high-level threshold2.2 V max.
Input low-level threshold0.6 V min.
Input hysteresis0.4 V min.; 1.2 V max.
Input leakage ¹50 μA @ 5 V, max.
Resolution32 bits
Time base stability50 ppm
Count rate0 to 25 MHz (external clock), 1 or 50 MHz (internal clock)
Input clock frequency, quadrature clocks
(ClkA or ClkB)
0 to 12.5 MHz, corresponding to these count rates:
x4: 0 to 50 Mcounts/s
x2: 0 to 25 Mcounts/s
x1: 0 to 12.5 Mcounts/s
Input clock frequency, mono clock0 to 25 MHz, corresponding to 0 to 25 Mcounts/s
Input signal functionsClockA (quadratureA/mono clock), ClockB (quadratureB clock), Index
Input signal compatibilityRS-422 differential, TTL/5VCMOS single-ended
Input CMV ¹-0.3 to +5.5 V (-4 to +8 V absolute max.)
Input differential voltage range±5.8 V (±12 V absolute max.)
Input differential high-level threshold200 mV max.
Input differential low-level threshold-200 mV min.
Input resistance ¹12 KΩ typical; 7 KΩ min.
Analog Inputs
Channels16 differential
Resolution16 bits
Conversion time3 μs
Settling time0 μs to 335 ms per sample, programmable in 1 μs steps
Differential input voltage ranges±1V, ±2V, ±5V, ±10V
AIN working voltage range (signal + CMV)±10V
Absolute maximum AIN voltage ¹-20 to +20 V continuous
-30 to +30 V peak (1 ms pulses, 10% duty cycle max.)
CMRR80 dB @ 1kHz, 65 dB @ 10kHz
Integral nonlinearity±1.5 LSB maximum
Differential nonlinearity±1.25 LSB maximum
Gain error±2 LSB typical, ±40 LSB maximum
Zero error±0.8 mV maximum
Input impedance (either AIN to AGND)> 10 MΩ in parallel with 100 pF
Analog Outputs
Channels8 single ended, with local (on-board) sensing
Resolution16 bits
Output ranges0 to +5V, 0 to +10V, ±5V, ±10V
Conversion time1.04 μs
Output current±2 mA maximum
Integral nonlinearity±2 LSB maximum
Differential nonlinearity±1 LSB maximum
Gain error±4 LSB typical; ±20 LSB maximum
Unipolar zero error5V range, 25°C: ±80 μV typical, ±200 μV maximum
10V range, 25°C: ±100 μV typical, ±300 μV maximum
5V range: ±140 μV typical, ±400 μV maximum
10V range: ±150 μV typical, ±600 μV maximum
Bipolar zero error±2 LSB typical; ±12 LSB maximum
Watchdog and Fail-safe
Timer stages3
Interval (per stage)Programmable from 20 ns to 85.9 s, in 20 ns steps
Output eventsStage 0: Fail-safe trigger, IRQ
Stage 1: NMI out via digital output, PCIe Fatal Error
Stage 2: Reset via digital output or onboard solid state relay (SSR)
Fail-safe controlIndependent enable and state for each of 48 digital I/Os, 8 analog outputs
Power and Environmental
System busPCI Express, x1, compliant to PCIe Specification 1.0a
DimensionsPCI Express standard height, half-length (6.55 in.)
Input power (nominal, w/no external loads)+12 V @ 350 mA, +3.3 V @ 450 mA
+5V out5VDC ±5%, 400 mA max. (total for all DIO/counter connectors)
Operating temperature0 to 70°C
Storage temperature-40 to 70°C


1: Applicable when 826 board is powered or unpowered.


File Version Type Size
Model 826 technical manual
Hardware and API documentation
3.0.10PDF894 KB
Quick start guide for WindowsPDF56 KB
Online user guide for Windows demoHTML
Application Notes
Model 826 tech support wiki
FAQs, examples and additional information
Open-source I2C emulator
How to control an I2C bus with model 826
Single and multistage watchdog timers
Introduction to watchdog timers: their architecture, function and application
1.0.0PDF296 KB
Statement of volatility
Memory attributes, for security and material-handling professionals
CE compliance reportPDF3.86 MB


File Version Type Size
Windows Software Development Kit
Compatible with Windows 10, 8, 7 and XP
3.3.9ZIP17.01 MB
Linux Software Development Kit3.3.10BZ2336 KB
LabVIEW Instrument Driver1.0.0ZIP1.13 MB
Other Operating Systems
Need a software development kit for another operating system? We can port our SDK to
your OS or provide the information you need to do it yourself. Contact Sales for details.

Pricing & Ordering

Model Description Qty 1 Qty 2-9 Order Qty.
826Multifunction analog/digital I/O$724$671
826C1Cable, flat, 26 conductor, 24 inch, for model 826$13$12
826C2Cable, flat, 50 conductor, 24 inch, for model 826$15$14
Breakout Boards
7503TDINBreakout board, 26-pin, DIN rail mountable$76$68
7505TDINBreakout board, 50-pin, DIN rail mountable$87$79
Solid State Relay Boards
7501T8Termination board, 8 G4 solid-state relay rack$94$91
Relays for Model 7501T8
RELAY-G4IAC5Solid state relay, 120V AC input$19$19
RELAY-G4IDC5Solid state relay, 10 to 32V DC input$19$19
RELAY-G4OAC5Solid state relay, 120V AC output$19$19
RELAY-G4ODC5Solid state relay, 60V DC output$19$19

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