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Up to 1 MHz, USB-AIO Series with 12 or 16-Bit Resolution

16 Channel, USB Multifunction Analog Input/Output Device


  • High-speed USB 2.0 multifunction DAQ
  • Sustained sampling speeds up to 1MHz
  • 16-bit or 12-bit resolution A/D converter
  • Flexible, software configured functionality
  • 16 single-ended or 8 differential analog inputs
  • 8 input ranges, 4 unipolar and 4 bipolar, channel-by-channel programmable
  • Autocalibration and oversampling for real-time accurate data
  • A/D starts via software, timer, or external trigger
  • Two or four 16-bit analog outputs; 4kHz update rate
  • 16 high-current digital I/O lines
  • Alternate micro-fit embedded USB header connector
  • USB/104 form-factor for OEM embedded applications
  • Small, (4" x 4" x 1.25") rugged industrial enclosure
  • All required power drawn from USB port, no external power adapter required
  • Type B USB connector features industrial strength and high-retention design
  • Now with Firmware 2.0 features!
    Onboard Watchdog Timer, configurable power-on defaults, digital input debouncing and latching, digital output Pulse Width Modulation (PWM) and Matrix Mapping
  • Designed, made, supported, and manufactured in the USA


  • Pseudo-differential analog inputs
  • External power for high current capabilities
  • Screw terminals for power input provide high retention connection
  • Industrial operating temperature (-40°C to +85°C)
  • OEM (board only) version for embedded applications
  • Single-ended current inputs (4-20mA or 10-50mA)
  • Voltage dividers per input
  • RoHS Available. Please contact us for ordering information
  • Support for Wind River VxWorks (call for ordering information)

The USB-AIO Series offers an ideal solution for adding portable, easy-to-install high-speed analog and digital I/O capabilities to any PC or embedded system with a USB port. These units are USB 2.0 high-speed devices, offering the highest speed available on the USB 2.0 bus. The USB-AIO16-16F is a 16-bit resolution A/D board capable of speeds up to 1MHz (in real-time operating systems) for its 16 single-ended (16 pseudo-differential optional) or 8 differential analog inputs. Each channel can be independently software configured to accept 8 different input ranges. A unique, real-time internal calibration system allows the card to continually compensate for offset/gain errors giving a more accurate reading. Additional features include 16 digital I/O lines and 0, 2, or 4 analog outputs. The unit is plug-and-play allowing a quick connection whenever you need additional I/O on the convenience of a USB port.

These small, compact, multifunction I/O units provide the user with everything needed to start acquiring, measuring, analyzing, and monitoring in a variety of applications. The USB-AIO Series data acquisition boards can be used in many current real-world applications such as precision measurement, analysis, monitoring, and control in countless embedded applications.

These units are designed to be used in rugged industrial environments but are small enough to fit nicely onto any desk or testing station. The board itself is PC/104 sized (3.550 x 3.775 inches, 90mm x 96mm) and ships inside a steel powder-coated enclosure with an anti-skid bottom. A DIN rail mounting provision and extended temperature is available for installation in industrial environments.

The boards feature eight standard analog voltage input ranges (independently configured), two factory current input ranges (4-20mA or 10-50mA) and include a data sample buffer.

Analog to digital conversion starts or “A/D starts” are issued one of three ways: Software Start, Timer Start, or External Trigger Start. A/D starts are software configured to be either rising or falling edge. Additionally, A/D starts are software configured to be Single Channel or Scan. Single Channel samples data once from the next consecutive channel within the enabled set. A Scan samples data from all channels within the set at the fastest possible rate.

A fully programmable 8254 16-bit counter is provided with a maximum input frequency of 10MHz. The clock, gate (inputs) and output can be accessed externally for extended functionality. The counter can be configured in a variety of modes and has the ability to use external signals for its inputs.


Advanced calibration models feature a unique real-time internal autocalibration system that allows the card to compensate for offset/gain errors, giving a more accurate reading. To minimize noise, the board offers a technique called oversampling. Additionally, each channel contains its own analog ground pin on the I/O connector which is helpful in reducing noise from external signal sources. The channel-by-channel programmable gain feature enables measurement of an assortment of large and small signals in one scan—all under software control at up to 500kHz. The board's data buffer and ability to trigger the A/D in real time assures synchronized sampling that is unaffected by other computer operations—an essential requirement for signal, vibration and transient analysis where high data rates must be sustained for short periods of time. More information regarding calibration can be found in the product manual.

Each board shipped from ACCES is factory calibrated as part of the production process using a high-quality 7 digit digital voltmeter (DVM) and an extremely stable voltage reference.

Firmware 2.0 Features

Onboard Watchdog Timer. If your application fails to communicate with the device within a specified timeout period (up to hundreds of seconds) the onboard intelligence will change all the output ports and values to the configured "safe" state.

Need a DAC to power up at 1 Volt? Want the digital output port to generate a square wave as soon as the firmware is loaded? Now you can configure the power-on default states for all possible outputs.

Command the onboard intelligence to perform digital input debouncing and latching. Debouncing time constants from hundreds of microseconds to hundreds of milliseconds allows a wide variety of low-pass filtering options. Latching inputs record low- and high-going pulses that your application may otherwise have missed.

PWM allows programmable duty-cycle square wave output on any digital output. MAP is our new Matrix Mapping feature, wherein you can command the onboard intelligence to automagically copy the state of one bit onto another bit, with no computer interaction required.


The OEM (board only) version is perfect for a variety of embedded applications. What makes the OEM option unique is that its PCB size and pre-drilled mounting holes match the PC/104 form factor (without the bus connections). This ensures easy installation using standard standoffs inside most enclosures or systems. The board can be integrated into any PC/104-based stack by simply connecting it to a USB port included on-board with embedded CPU form factors. The USB-AIO Series OEM boards can also be installed using standoffs inside other enclosures or systems. For embedded OEM type applications, an additional micro-fit USB input header is provided in parallel with the type B connector.

High Retention USB Connector

The ever-growing presence of USB in the industrial/military marketplace has driven the need for USB connections to be reliable, dependable, and unfailing. Gone are the days of loose USB connections. A type B USB connector is used on all ACCES USB/104 products which features a high retention design that complies with the class 1, Div II minimum withdrawal requirement of over 3 pounds of force (15 Newtons). This connector has an orange color-coded insulator to quickly differentiate it from standard USB connectors. Using these USB connectors increases reliability in your system and ensures a tight connection. For embedded OEM type applications, an additional micro-fit USB input header is provided in parallel with the type B connector.


  • Equipment monitoring
  • Environmental measurements
  • Embedded OEM
  • Education/Laboratory
  • Portable
  • Industrial Automation
  • Precision Measurement
  • Analysis, Monitoring, and Control


Available accessories include a wide variety of cables and screw terminal boards for quick and easy connectivity. Also, a DIN rail mounting provision is available.

Need more isolation?

Isolate your I/O with our USB-ISOLATOR accessory! Tru-Iso™ signal isolation up to 4kV meets EN60601 standards in a rugged industrial-grade, extended temp (-40 to +85°C) package — no connection to power needed! Use with our 1-foot USB cable and avoid tangles. OEM-version available, featuring picoblade microfit headers for hassle-free embedded cabling.

Available Reference Manuals

Available Software Downloads

Available Datasheets

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..

USB and Performance

Our USB Data Acquisition products use our "AIOUSB" driver package in Windows and Linux. This driver package includes 32-bit and 64-bit support, and consists of low-level driver components and a high-level API library. This custom interface driver enables our USB devices to achieve 4000 transactions per second, compared to the competitions' "HID" drivers that cap out around 50 transactions per second. You can read all about the API in the USB Software Reference Manual linked below, and included in every applicable Software Package. (The Linux version of the AIOUSB API is almost identical to the Windows API, and is documented in the aiousb.html file included in the Linux software package.) Like all of our software, full source code is always provided.

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.


ACCES has successfully partnered with Wind River to bring our entire line of USB DAQ boards to VxWorks 7!

Our newly available driver and easy-to-use API-library, including full source and sample code, supports ReNumeration for loading firmware across the USB cable as well as our GenericVendorWrite and GenericVendorRead functions, compatible with our Windows AIOUSB.dll API. Additional AIOUSB API functions are being ported, ask for details!

With our aioUSB.VxWorks library USB DAQ can now be used with the utmost confidence for real-world/real-time/rugged applications. Using VxWorks 7 as the solid foundation, and positive-retention cables in either micro-fit or USB-B-with-screw, as well as rugged steel enclosures and DIN-Rail or PC/104-mounting options, USB is no longer "just for desktops".

You can find more information about our VxWorks libraries and services on our Wind River Silver Partner page.

Analog Inputs

ADC Type        Successive approximation
Resolution      12 or 16-bit
Sampling rate
 "16-16F" version   1M samples/sec (maximum aggregate)
 "16-16A" version   500Ksamples/sec (maximum aggregate)
 "16-16E" version   250Ksamples/sec (maximum aggregate)
 "12-16A" version   500Ksamples/sec (maximum aggregate)
 "12-16" version    250Ksamples/sec (maximum aggregate)
 "12-16E"version    100Ksamples/sec (maximum aggregate)
Number of channels  16 single-ended or 8 differential (software selectable) 
(16 pseudo-differential factory option available) Unipolar ranges 0-1V, 0-2V, 0-5V, 0-10V (software selectable) Bipolar ranges ±1V, ±2V, ±5V, ±10V (software selectable) 4-20mA Factory installed (optional) 10-50mA Factory installed (optional) Calibration Hardware "16-16F" version Two on-board references + calibrated real-time output "16-16A" version Two on-board references + calibrated real-time output "16-16E" version Two on-board references "12-16A" version Two on-board references + calibrated real-time output "12-16" version Two on-board references "12-16E"version NONE System Calibration Program provided to calibrate entire system Accuracy Uncalibrated 0.094% Full-Scale (FS) Calibrated(*) 0.0015% FS Int Nonlinearity Error 0.0011% FS No Missing Codes 16 bits Input impedance 1MΩ A/D Start Sources Software Start, Timer Start, and External Start Trigger (rising or falling edge; software selectable) A/D Start Enable Externally supplied (pulled-up; active-high) A/D Start Types Single Channel or Scan (software selectable) Channel Oversampling 0-255 consecutive samples/channel (software selectable) Overvoltage protection -40 to +40V Crosstalk -53dB @ 1MHz;84dB @ 500KHz (*) To achieve best accuracy, one must calibrate to their own standard

Analog Outputs

Number/Type         2 or 4/single-ended
Resolution          16-bit
Unipolar Ranges     0-5V*, 0-10V*
Bipolar Ranges      ±5V*, ±10V*
Conversion Rate     4kHz per channel
Settling Time       4us typ, 7us max; 1/4 to 3/4 scale to ±2LSBs
Output Current      ±10mA per channel

* Factory Options

Digital I/O

Lines               16, programmable as inputs or outputs in groups of 8 (pulled-up via 10KΩ)
Input voltage       Logic low:  0V(min) to 0.8V(max)
                    Logic high: 2V(min) to 5V(max)
Input current       ±20µA (max)
Output voltage      Logic low:  0V(min) to 0.55V(max)
                    Logic high: 2V(min) to 5V(max)
Output current      Logic low:  64mA(max) sink
                    Logic high: 32mA(max) source


Operating Temperature   0° to +70°C, optional -40° to +85°C
Storage Temperature -40° to +105°C
Humidity        5% to 95% RH, without condensation
Board Dimensions    PC/104 format, 3.550” by 3.775” w/ mounting holes
Power required      +5V at 315mA typical*

*USB 2.0 spec defines a device in terms of a unit load. A unit load is defined to be 100mA. Devices drawing an absolute maximum of one unit load is considered to be low-powered and devices drawing an absolute maximum of five unit loads is considered to be high-powered. Because this spec is not strictly adhered to, it is best to verify the USB port's power capabilities before operation. This card, according to the USB 2.0 spec, is a high powered device. An optional external power supply can be ordered if the USB port cannot support high powered devices.

If using more than a total of 500mA, use optional 9 VDC external power supply and remove VUSB jumper and place jumper on VEXT. Then plug in external power before plugging into USB port . This option will give you a total of 1000mA available.

Included with your board

The following components are included with your shipment:
  • Board installed in labeled enclosure
  • 6’ USB cable

ModelPrice (USD)

Need more isolation?

Isolate your I/O with our USB-ISOLATOR accessory! Tru-Iso™ signal isolation up to 4kV meets EN60601 standards in a rugged industrial-grade, extended temp (-40 to +85°C) package — no connection to power needed! Use with our 1-foot USB cable and avoid tangles. OEM-version available, featuring picoblade microfit headers for hassle-free embedded cabling.

USB-AIO16-16F16-Bit, 1MHz, with real-time autocalibration, 2 analog outputs and 16 digital I/O
USB-AIO16-16A16-Bit, 500kHz, with real-time autocalibration, 2 analog outputs and 16 digital I/O
USB-AIO16-16E16-Bit, 250kHz, with software calibration, 2 analog outputs and 16 digital I/O
USB-AI16-16F16-Bit, 1MHz, with real-time autocalibration and 16 digital I/O
USB-AI16-16A16-Bit, 500kHz, with real-time autocalibration and 16 digital I/O
USB-AI16-16E16-Bit, 250kHz, with software calibration and 16 digital I/O
USB-AIO12-16A12-Bit, 500kHz, with real-time autocalibration, 2 analog outputs and 16 digital I/O
USB-AIO12-1612-Bit, 250kHz, with software calibration, 2 analog outputs and 16 digital I/O
USB-AIO12-16E12-Bit, 100kHz, 2 analog outputs and 16 digital I/O
USB-AI12-16A12-Bit, 500kHz, with real-time autocalibration and 16 digital I/O
USB-AI12-1612-Bit, 250kHz, with software and 16 digital I/O
USB-AI12-16E12-Bit, 100kHz, and 16 digital I/O
STB-6868-pin screw terminal board $69
STB-68 KitUsed for mounting the STB-68 to the enclosure of both the USB-AI and Fast USB-DIO Series of USB products. Includes STB-68, cable and specialized mounting hardware. $89.00
C68MM-1.7568-pin male to male SCSI ribbon cable, 1.75 inches long. $19
C68MM-1.0068-pin male to male SCSI ribbon cable, 1.00 inches long. $19
104-HDW-KIT (X)Hardware kit for stacking boards; includes 4 screws, nuts and standoffs. Specify metric (M) or standard (S). $10
MP104-DINDIN rail mounting provision $19
C68PS18L68-pin SCSI 18" shielded cable $29.00
Model Options (call for pricing)
-OEMBoard only version (no enclosure)
-PExternal power components and AC/DC adapter
-TExtended operating temperature (-40°C to +85°C)
-STExternal power connection via screw terminals (high retention)
-4AOFour analog outputs
-PDPseudo-differential analog inputs
-RoHSRoHS compliant version
Call4-20mA or 10-50mA inputs
Call16 current inputs when factory configured as single-ended
Call8 current inputs when factory configured as differential
-5UAnalog output voltage range of 0-5V only
-10UAnalog output voltage range of 0-10V only
-5BAnalog output voltage range of ±5V only
-10BAnalog output voltage range of ±10V only
CallDIO lines can be configured with pull down resistors
S0xSpecial configurations (input voltage dividers, conformal coating, etc.)

Acquisition, Control, Communication: Engineering and Systems