Multifunction analog/digital I/O w/serial COM | Model 2426

Model 2426 Multifunction analog/digital I/O w/serial COM
  • Controls & monitors real world signals over Ethernet
  • 8 isolated digital inputs w/debounce
  • 16 digital outputs w/PWM mode & integrated support for safety interlocks
  • 6 12-bit analog inputs
  • 12-bit analog output
  • RS-422/RS-485 async serial port
  • Incremental encoder interface
  • Embedded HTTP/Telnet servers
  • Open source API
  • Low cost, low power & compact size
  • DIN-3 rail mountable


Model 2426 is a versatile open-frame module that interfaces a variety of real world signals to a 10/100 Mbps Ethernet. It has eight optically isolated digital inputs, 16 digital outputs, six 12-bit analog inputs, one 12-bit analog output, an asynchronous serial port with RS-422/RS-485 phy, and a high speed incremental encoder interface, all powered by an external 24 VDC supply (not included). The module's compact footprint allows it to fit into tight spaces, and the built-in DIN rail mounting hardware makes installation quick and easy.

2426 Block Diagram


Network servers

Remote network clients communicate with the module via its built-in servers (telnet for manual and automated control; HTTP for configuration, manual control, and diagnostics), which allows any web browser or telnet client to remotely monitor and control I/O without any special device drivers or proprietary software. In the case of telnet, commands and replies are conveyed in plaintext, which can dramatically reduce development time and simplify maintenance.

2426 Control page screenshot

Model 2426 Control page

Control page viewed on an HTC Hero (Google Android) browser

2426 control page as seen on HTC Hero (Google Android) browser

Software development kit

A free software development kit is available for model 2426 which includes documentation, sample applications and a comprehensive application program interface (API). Pre-built API libraries are included for Linux and Windows, along with API source code (C language) and instructions for OEM customization and porting.

The API transparently handles all of the underlying telnet and module command protocols so that programmers can focus on application development. For example, application software can simply call the s2426_WriteDout() function to program the general purpose digital outputs.

Concurrent access

The module supports simultaneous communication with multiple clients. For example, maintenance personnel can plug into the network and monitor the module while, at the same time, the module is controlled by an automation process running on another computer.

Furthermore, the API allows any process to utilize multiple concurrent sessions. A typical application of this is to have one thread handle RS-422/RS-485 serial communication while another thread interacts with I/O interfaces on a separate session, resulting in straightforward application code that tends to be robust and easily maintained.

Watchdog timers

A hardware watchdog timer will reset the module in the event of an internal module malfunction. In addition, a communication watchdog will trigger a module reset if a client fails to communicate with the module in a timely manner. In both cases, the reset will automatically force all outputs to "safe" states.

Support for safety interlocks

Each digital output can be configured to unconditionally deactivate its output driver when an associated contact (e.g., safety interlock, emergency stop switch) is open. Implementing this commonly required feature in the module allows external termination boards to be eliminated and wiring to be simplified, with a commensurate reduction in system complexity and cost.

Digital output block diagram

Digital output block diagram

Typical interlock application

Interlock application example


2426TA termination board

An optional breakout termination board, model 2426TA, is available for model 2426. It plugs directly onto the 2426 module with board-to-board interconnects — minimal overhead space is used and no cables are needed. Field wiring can then be quickly and easily inserted into the 2426TA's spring terminal blocks.

2426TA breakout termination board



Communication Interfaces
Network Physical layer10BaseT, 100BaseTx Ethernet
Bit rate10/100 Mbps, auto-detecting
ConfigurationProgrammable via HTTP (static ARP): IP address, netmask, gateway
HTTP Server Concurrent sessions0 to 1
FunctionsStatus, configuration, I/O monitor/control
TELNET Server Concurrent sessions0 to 3
Time-out interval5 minutes (default, reprogrammable via HTTP), programmable per session via shell
Async Serial COM Physical layerRS-422 or RS-485, shunt configurable
Bit rate300 bps to 115.2 Kbps, software selectable
Termination (RS-422/485)120 ohms ±5%, transmit and/or receive pair, enabled via shunts
Receiver turnaround250 µs maximum
Telnet protocol optionsCom Port Control (RFC 2217), Binary Transmission (RFC 856)
Timestamp Generator Count rate1.0 MHz
Resolution32 bits, 1.0 µs
Analog Interfaces
Analog Inputs Channels6 external, 2 internal reference
Resolution12 bits
Input typeDifferential
Differential input range-10V to +10V, minimum (at 0V CMV)
CMV input range-10V to +10V
Input impedance22M ohms minimum
Conversion rate1000 samples/s per channel
Inter-channel acquisition skew125 µs maximum
TriggerInternal hardware timer
Data formatSigned 16-bit integer with timestamp
Analog Output Resolution12 bits
Output range-10V to +10V, minimum
Settling time500 µs maximum (20V step change)
Data formatSigned 16-bit integer
Encoder Interface
Encoder Interface Resolution32 bits
Count rate0 to 30 MHz
Clock rate0 to 7.5 MHz
Clock/Index input signalsRS-422 differential, TTL/5VCMOS compatible, ±7V CMV maximum
Encoder power output5VDC ±5%, 100mA maximum
Data formatSigned 32-bit integer with timestamp
Digital Interfaces
Digital Inputs Channels8
Input typeDifferential pair, optically isolated with 4.7 Kohm series impedance
Input range+5V to +24V
Digital Outputs Channels16
Output typeActive low, open collector drive with inductive load EMF suppression diode
Output high-level voltage sourceInternal, shunt selectable from continuous 24V or any interlock power source
Output current100 mA maximum per channel, 500 mA maximum total
Power and Environmental
Module Power Input power24VDC ±5% @120mA (digital outputs off, no external loads)
Interlock Power Channels5
Voltage range+5VDC to +24VDC, referenced to module input power
Current500mA maximum, per circuit
Temperature Operating range-25 to 85 °C
Module Dimensions Outer dimensions(W x H x D): 5.3 x 5.0 x 2.2 inches
W = DIN rail length
D = module height from DIN rail back panel; additional clearance required for field wiring.
Mating Connectors
(*) = included with module
EthernetRJ-45 plug, AMP 554169 or equivalent
Terminal block (*)Pluggable TB, Phoenix Contact or equivalent
Serial COMDB-9 male, Norcomp 171-009-102-001 or equivalent
EncoderDB-9 female, Norcomp 171-009-202-001 or equivalent
Analog I/ODB-25 female, Norcomp 171-025-202-001 or equivalent
Digital inputsDB-37 female, Norcomp 171-037-202-001 or equivalent
Digital outputsDB-37 male, Norcomp 171-037-102-001 or equivalent


File Version Type Size
Model 2426 Technical Manual1.0.1PDF357 KB
Model 2426 Mechanical Dimensions1.0.0PDF188 KB


File Version Type Size
2426 Software Developer's Kit (SDK)1.0.2ZIP711 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.
2426Multifunction analog/digital I/O w/serial COM$400$363
Optional Accessories
2426TATermination board for Model 2426, top mounted$145$133

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