Multifunction analog/digital I/O | Model 425

Model 425 Multifunction analog/digital I/O
  • Three quadrature encoder channels with 24-bit counters
  • Four 12-bit D/A outputs
  • Eight 12-bit differential A/D inputs
  • Watchdog timer
  • 48 bidirectional digital signals
  • Interrupts from counters and digital I/Os

Model 425 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. Use our Product Finder to find a comparable product or contact our Design Support Team.


Sensoray's model 425 is a low-cost ISA bus interface that combines five popular functions on one board. It uses four low-profile headers and flat cables to connect its I/O interfaces to external breakout boards.

Typical Application


Encoder Interfaces

The board's 24-bit up/down counter channels are designed to work with incremental encoders or single-phase clock sources. Each channel accepts two TTL or RS-422 clock signals, plus an index signal, to track encoder direction and displacement. Unlike conventional counters, the board's counters do not accumulate errors when the encoder dithers or changes direction. The board supplies 5-volt operating power to all encoder channels through its connectors. Each counter can be programmed to function as an encoder interface or as a general-purpose timer and may optionally generate interrupts. To ensure maximum flexibility, no counter functions are shared by any other on-board peripheral devices.


Eight differential input channels are multiplexed to a sample/hold and high-speed A/D converter. A resistor-programmable instrumentation amplifier allows gains of 1 to 1000. An on-board DC/DC supply ensures A/D linearity for the full ±10 V input range.


The board has four analog output channels with a 0 to 10 V output range. One of the channels has remote sense inputs to compensate lead loss errors. All outputs are automatically reset to 0 V when a bus or soft reset occurs.


The board's watchdog timer output may be routed to either bus reset or nonmaskable interrupt. It may be enabled or disabled under program control. The timer is automatically disabled when a bus reset occurs.

Digital I/O

Model 425 has forty eight high-current digital I/O channels. The connector pinouts allow the channels to be directly connected to industry-standard solid relay boards. Each line is independently configurable as input, output, or wired-OR. Sixteen of the channels support edge detection with interrupts. When a system reset occurs, all output channels are automatically turned off.


Analog Inputs
Conversion time20 µS
Number of channels8 differential
Input resistance100 MΩ
CMRR100 dB minimum
Maximum common mode voltage5 V
Resolution12 bits
Accuracy14 bits
Input ranges±10, ±5 V
Offset error±1/2 LSB
Analog Outputs
Conversion time200 µs
Resolution12 bits
Offset error±2 LSB
Output voltage±10 V
Output resistance87 Ω
Digital I/O
Number of channels48 bi-directional
Output voltage0 to 5 V, open collector
Output sink current100 mA (at 1.1 V)
Encoder Interfaces
Number of channels3 quadrature, 16 bit
Input voltageTTL or RS-422
Input frequency350 kHz
Watchdog Timer
Watchdog timer time-outTime-out: 500 ms
2-pin connector may be connected to the bus reset line to allow a system reset from software
Power and Environmental
Operating temperature-25 to 70 °C
PC bus interfaceI/O mapped, 16 ports
Input power< 3 W


File Version Type Size
Model 425 Instruction Manual1.0.0PDF351 KB


File Version Type Size
Model 425 Software Development Kit1.0.0ZIP1.23 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.
425Multifunction analog/digital I/OCallCall 
Breakout Boards
7502TDINBreakout board, 20-pin, DIN rail mountable$53$53
7505TDINBreakout board, 50-pin, DIN rail mountable$87$79
7506TDINBreakout board, 40-pin, DIN rail mountable$85$78
7409CCable, flat, 40 conductor, 18 inches$21$20
7409C1Cable, flat, 40 conductor, 1 meter$31$28
7501CCable, flat, 50 conductor, 18 inches$19$17
7501C1Cable, flat, 50 conductor, 1 meter$33$30
7502CCable, flat, 20 conductor, 18 inches$14$13
7502C1Cable, flat, 20 conductor, 1 meter$28$26

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