Model 2426 | Multifunction Analog/Digital I/O w/Serial COM

Model 2426 Multifunction Analog/Digital I/O w/Serial COM
  • Controls/monitors real world signals over Ethernet
  • 24 digital I/O with PWM mode and debounce
  • Six 12-bit analog inputs
  • One 12-bit analog output
  • 1 serial COM port
  • 1 incremental encoder interface
  • Integral support for safety interlocks
  • Embedded HTTP and 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, sixteen digital outputs, six 12-bit analog inputs, one 12-bit analog output, one RS-422/RS-485 serial communication port, and a high speed incremental encoder interface.

2426 Block Diagram


The module includes a number of features that simplify its installation and system integration:

  • Its compact footprint allows it to fit into small spaces.
  • Powered from a single 24VDC supply.
  • DIN mounting feet expedite installation; the unit can be quickly and easily mounted by simply snapping it onto a standard DIN mounting rail.
  • The unit communicates by means of standard embedded servers: Telnet for manual and automated control, and HTTP for configuration, manual control, and diagnostics.
  • Precompiled API libraries are available for Linux and Windows, along with open source (C language) code for applications that require customization or porting.

Network Servers

Built-in HTTP and telnet servers enable any web browser or telnet client to access the module's I/O interfaces. These standardized protocols make it possible to monitor and control I/O across a network without any special device drivers or proprietary software. In the case of telnet, remote shell commands and replies are conveyed in plaintext, resulting in dramatically shorter development time and simplified 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

The module supports concurrent telnet sessions so that multiple threads and hosts can communicate with it at the same time. For example, maintenance personnel can plug into the network and monitor the module's operation over a private telnet session while, at the same time, the module is controlled by a remote automation process running on a different session. Furthermore, the automation process itself is not limited to a single telnet session; for example, it could have two threads—one to handle serial port communications and another to control other I/O interfaces—with each thread running its own independent telnet session. Consequently, system design is simplified and systems tend to be robust and easily maintained.

Safety Features

Model 2426 features several special mechanisms that can be used to enhance the safety of application systems:

  • A hardware watchdog timer will reset the module in the event of a malfunction by the module's internal controller, thus forcing all outputs to their "safe" states.
  • A communication watchdog timer constantly monitors network communications. If a network client fails to communicate with the module in a timely manner, the module will be automatically reset.
  • Each digital output channel incorporates circuitry that will unconditionally deactivate the output driver if an associated contact (e.g., safety interlock or emergency stop switch) is open. By implementing this essential function within the module, external termination boards can be eliminated and wiring simplified, with a commensurate reduction in system complexity and cost.

Digital output channel block diagram

Digital output channel block diagram

Typical interlock application

Interlock application example

Open Source SDK

A software development kit (SDK) is available for the 2426 that includes documentation, sample applications and a comprehensive application program interface (API). The API transparently handles all underlying protocols so the programmer can focus on application development. For example, an application program can simply call the API's s2426_WriteDout() function to update the module's general purpose digital outputs. The SDK includes pre-built API libraries for Linux and Windows, along with open source API code (C language) with instructions for OEM customization and porting.

2426TA Termination Board

An optional breakout termination board, model 2426TA, is available for the 2426. It plugs directly onto the 2426 with board-to-board interconnects so that 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.




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$374$339
2426TATermination Board for Model 2426, Top Mounted$136$124

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