Model 626 | Multifunction Analog/Digital I/O

  • Six versatile 24-bit counters support incremental encoders
  • 48 bi-directional digital I/O -- 40 with edge detection
  • Four 14-bit analog outputs, 20 KHz update rate
  • Sixteen 16-bit differential analog inputs, 15 KHz rate
  • Watchdog timer with mechanical relay output
  • Battery backup of counters

Model 626 is a legacy product and is not recommended for new designs. Legacy products are available but may have lead times up to 12 weeks and minimum order requirements. We recommend model 826 as a substitute for this product.


Model 626 is a PCI board that saves space and reduces cost by combining several popular interface functions on a half-size card. It has six versatile 24-bit counters that support incremental encoders as well as single-clock sources, 48 bidirectional digital I/Os (40 with edge detection), sixteen differential analog inputs, four analog outputs, and a watchdog timer. Five low profile connectors are used with optional flat cables to connect the board to external breakout boards.

Typical application


Encoders and Counters

Three 24-bit up/down counter pairs may be configured for six incremental encoders, each having 24-bits of resolution. Each channel accepts two phased TTL or RS-422 signals plus an index signal to track encoder direction and displacement. Each input is conditioned and synchronized to the 626’s internal clock.

Unlike conventional counters, the 626’s counters do not accumulate errors when the encoder dithers or changes direction. The 626 supplies 5 volt power to each encoder channel. All counters are programmable and may optionally generate interrupts.

The counter channels have a battery backup feature that keeps them running during a power failure. The 626’s battery charger will recharge an external 3.6V NiCd when power is restored.

Each counter can function as a timer using the board's internal clock or an external clock. When paired, 48-bit counters may be used for frequency measurement.

Analog Inputs

Sixteen differential input channels are multiplexed to a sample/hold and successive approximation A/D. Each channel may be programmed for ± 5V or ± 10V. No trim adjustments are needed.

Analog Outputs

Four voltage outputs may be programmed for ± 10 volts. A unique circuit prevents unpredictable D/A outputs during CPU initialization. All outputs are reset to zero volts whenever a bus reset occurs.

Watchdog Timer

The board's watchdog timer may be connected to the bus reset via a 2-pin connector. It may be enabled or disabled under program control. The timer is automatically disabled whenever a bus reset occurs. A mechanical relay is provided to signal external circuitry. The relay can be activated by the watchdog timer or under software control.

Fail-safe Digital I/O

In the event that power is lost to the PC, solid state relays connected to the 626’s digital I/O will not be powered to the on state.  This allows solid state relay boards to be powered from a remote power supply without the chance of output relays turning on when the PC is turned off.

Digital I/O

The board's 48 digital lines have standard pinouts for solid state relay boards. Each line is software programmable as an input or output. 40 of the inputs may be independently programmed for edge detection. All outputs are turned off upon system reset.


Analog Inputs
Number of channels 16 differential
Conversion time 20 µs/channel
Input resistance 100 MΩ
CMRR 100 dB minimum
Maximum common mode voltage ±5 V
Resolution 16-bits
Accuracy 14-bits
Input ranges ±10 V, ±5 V
Offset error ±1/2 LSB
Analog Outputs
Channels 4
Conversion time 200 µs/channel
Resolution 14 bits
Offset error ±2 bits
Output voltage ±10 V
Output resistance 87 Ω
Digital I/O
Number of channels 48 bi-directional
Output voltage 0 to 5 V open collector
Output sink current 100 mA (at 1.1 V)
Connector 50 pin, low profile, for flat cable
Channels 6, 24 bits, quadrature-encoded or single-clock
Input signals TTL or RS-422
Input frequency 2 MHz with internal clock
1 MHz with external clock
Quadrature multiplier x1, x2, x4
Battery backup NiCd, 3.6 V
Connector 26 pin, low profile, for flat cable
Watchdog Timer
Watchdog Timer Time-out 1/8, 1/4, 1, 10 sec
Bus interface PCI, 32-bit, 33 MHz
3.3V/5 V universal bus signaling
Board dimensions 4.2 x 7.0 in (107 x 178 mm)
Input power < 3 W
Operating temperature 0 to 70 °C


File Version Type Size
Model 626 Instruction Manual1.0.5PDF335 KB
Images and Mechanical Drawings
Dimensional Drawing1.0.0PDF33 KB


File Version Type Size
Model 626 Linux Software Development Kit1.0.5GZ183 KB
Model 626 Windows Software Development Kit
Compatible with Windows XP
1.0.0ZIP386 KB
Model 626 Windows Software Development Kit
Compatible with Windows 7
1.0.0ZIP994 KB
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.
626Multifunction Analog/Digital I/O$677$627
Termination Boards
7503TDINBreakout board, 26-pin, DIN rail mountable$71$64
7505TDINBreakout board, 50-pin, DIN rail mountable$81$74
7503CCable, flat, 26 conductor, 18 inches$18$16
7503C1Cable, flat, 26 conductor, 1 meter$31$26
7501CCable, flat, 50 conductor, 18 inches$18$16
7501C1Cable, flat, 50 conductor, 1 meter$31$28

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