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Availability: Obsolete
OBSOLETE - PAC Ethernet Brain, analog/digital/serial, with high-speed digital functions

Production Specification

NOTE: Due to the unavailability of essential parts, SNAP PAC EB-series brains have reached their end of life as of March 1, 2022. Instead, use a SNAP-PAC-R1 controller/brain; it has all the same features plus additional power (and programmability, if you need it).

This brain is an I/O and communications processor for your control system. Designed primarily to work in distributed systems controlled by a SNAP PAC S-series or R-series controller, this brain can also be controlled by a groov EPIC processor or used as intelligent remote I/O with Allen-Bradley industrial PLC systems. This brain provides local intelligence that frees the controller (PAC, EPIC, or PLC) for supervisory tasks.

As an I/O processor, the SNAP PAC brain independently handles functions such as latching, counting, thermocouple linearization, watchdog timers, and PID loop control. These functions continue to work on the brain even if communication with the controller is lost.

The SNAP-PAC-EB1-FM brain supports all the SNAP I/O analog, digital, and serial input and output modules available on the Opto 22 website. These modules can all be mixed on the same mounting rack and placed in any position on the rack. The brain and modules mount on a SNAP PAC rack, which holds up to 4, 8, 12, or 16 modules.

NOTE: In order to use Opto 22 serial modules with an EB2 brain, the I/O should be controlled by a SNAP PAC controller or groov EPIC processor running a PAC Control strategy.

In addition to I/O processing, the SNAP PAC brain communicates over a standard 10/100 Mbps Ethernet network. The brain is equipped with two switched Ethernet network interfaces. Because these interfaces share a single IP address and act just like an Ethernet switch, SNAP PAC brains can be installed in a multi-drop (daisy-chain) configuration, extending the control network without the added expense of additional Ethernet network hardware. SNAP PAC brains can also be installed in a star configuration using standard, off-the-shelf Ethernet network components.

The SNAP-PAC-EB1-FM brain supports communication using multiple protocols running simultaneously over Ethernet. Most customers use the PAC Project software suite for control, monitoring, and data acquisition. At the same time, you can communicate using other methods, including EtherNet/IP, Modbus/TCP, SNMP, SMTP, FTP, and OptoMMP. Communication with OPC 2.0-compliant clients is available through OptoOPCServer. Additional programming options are available when the EB is used with a groov EPIC processor.

This brain offers high-speed digital functions, including high-speed counting (up to 20 KHz, depending on the module), quadrature counting, pulse generation and measurement, and TPO (time-proportional output). Pulse generation and measurement require PAC Control and a SNAP PAC controller or groov EPIC processor, or using the brain with Allen-Bradley PLC systems. For a complete list of features and specifications, see form #1689, the SNAP PAC Brains Data Sheet, under the Docs & Downloads tab.

Compare SNAP PAC controllers and brains.

If you are not using PAC Project software and a SNAP PAC controller or groov EPIC processor with this brain and instead need to communicate directly with it, see the SNAP PAC .NET OptoMMP SDK.

Build your system in the SNAP I/O Configurator.

Ethernet and Serial Brains [Ethernet Brains are Obsolete 3/1/22]

Power Requirements

5.0–5.2 VDC at 750 mA maximum (does not include module power requirements)



Backup battery for real-time clock

Rechargeable (recharges whenever the brain has power). 5-year life when power is off (replacement part number: SNAP-PAC-BATTERY-ML2430). (Models manufactured before August 2007 have a 3-volt CR2032 lithium battery, available in retail stores. See original user guide for replacement steps.)

Hold-down screw

Torque: 8 in-lb (0.9 N-m)

Operating Temperature

-20 to 60 °C

Storage Temperature

-40 to 85 °C


0–95% humidity, non-condensing

Agency certifications

-EB models: UL, CE, RoHS, DFARS; UKCA
-SB models: CE, RoHS, DFARS; UKCA


30 months from date of manufacture

Ethernet Brains (EB) only

Ethernet Net­work Interfaces

IEEE 802.3 network, 10Base-T and 100Base-TX. Supports Auto MDI-X (crossover cable not needed). Two switched interfaces, allowing multi-drop (daisy-chain) or standard star network configuration.

Maximum Ethernet Segment Length

100 meters with Category 5 or superior UTP
For 100 Mbps at this distance, use Category 5 or superior solid UTP.

Serial Brains (SB) only

Network interfaces

RS-485, 2- or 4-wire, twisted pair(s), with shield

Serial data rates

300 baud to 230.4 Kbaud

Range: Serial multidrop

32 stations maximum on a segment (including PC, controller, repeaters, and I/O units); up to 3000 ft (914 m) on a segment

Using Modbus Devices with Opto 22 Products Technical Note

This technical note introduces the Modbus protocol and gives you basic information for using it to communicate between Opto 22 products and other devices. Because Modbus/TCP and Modbus serial are handled differently by various manufacturers, the tech note describes specific areas that may be a concern and includes troubleshooting suggestions.

SNAP PAC Controllers and Brains Firmware README

This README file lists revision changes made to the firmware used in SNAP PAC S-series, R-series, and SoftPAC controllers; SNAP PAC EB-series and SB-series brains; and G4EB2 and G4D32EB2 brains.

SNAP PAC I/O Coprocessor Firmware README

This README file lists changes to the I/O coprocessor firmware available in rack-mounted Opto 22 controllers and brains manufactured starting in 2016.

I/O coprocessors can be present in the SNAP PAC R-series controllers, and in SNAP PAC EB-series and SB-series brains. Instructions to find out if your device has an I/O coprocessor are included in this README and in the PAC Manager User's Guide.

NOTE: The following products manufactured with I/O coprocessors have firmware R3.0a; you do not need to update the firmware in these products at this time:


EtherNet/IP for SNAP PAC Protocol Guide

This guide provides detailed descriptions of the EtherNet/IP commands that can be accessed when using remote Opto 22 I/O with an Allen-Bradley controller.

Case Study: J.A. King

Whether it’s making sure grains are stored without excess moisture, weighing raw materials for chemical production, or batching and mixing ingredients for baked goods, automation is key to better results. System integrator J.A. King reduces costs for customers in a variety of material handling and mixing applications.

Case Study: Amalgamated Research, LLC

As the research and development department of Amalgamated Sugar in the 1970s, ARi began with a mission to develop efficient processes to extract sugar from sugar beets.

But over time, their continuous research in the industrial separation field has led them far beyond sugar.

White Paper: The Case for Intelligent Remote I/O

This white paper explores the use of intelligent remote I/O in industrial automation systems. Employing a distributed architecture, rather than centralized control, offers three advantages: minimizing single points of failure, spreading the load, and maximizing scalability.

The paper details applications that could be made more efficient by using built-in functions offered by intelligent remote I/O. It also gives a specific example of how distributed intelligence could be used in a PLC system.

Quick Guide: Troubleshooting Info from SNAP PAC Systems

This technical note provides a quick guide about diagnostic files to collect and send in to Opto 22 Product Support for analysis when troubleshooting a SNAP PAC System.

White Paper: Adding Process Control to a PLC-Based System

This white paper discusses the strengths of traditional programmable logic controller (PLC) systems and distributed control systems (DCSs). The paper weighs methods of adding process control to a PLC-based system and proposes distributed I/O processing as the best method. It also introduces intelligent remote SNAP I/O, which adds process control analog functions.

Updating the Loader on a SNAP Device

It is rarely necessary to update the loader in a SNAP PAC controller or brain, but if you need to, this document shows you how. If you have questions, contact Opto 22 Product Support.

Expanding Allen-Bradley Systems with Intelligent Remote I/O (Chinese)

This document is written in Chinese.

This white paper explores a new way to expand Allen-Bradley PLC systems, adding functionality as well as additional I/O, with less strain on the central PLC and little programming.

Expanding Allen-Bradley Systems with Intelligent Remote I/O

This white paper explores a new way to expand Allen-Bradley PLC systems, adding functionality as well as additional I/O, with less strain on the central PLC and little programming.

I/O Solutions for Temperature Monitoring (Chinese)

This document is written in Chinese.

This white paper describes various temperature sensors such as RTDs, thermocouples, ICTDs, thermistors, and infrared sensors, and the Opto 22 solutions for using them.

Primer: I/O Solutions for Temperature Monitoring

This primer describes various temperature sensors such as RTDs, thermocouples, ICTDs, thermistors, and infrared sensors, and the Opto 22 solutions for using them.

EtherNet/IP Implementation in SNAP PAC Products

This technical note summarizes EtherNet/IP technology and how SNAP PAC devices can be integrated into an EtherNet/IP environment to send data to EtherNet/IP enabled devices such as Allen-Bradley PLCs.

Opto 22 RoHS 3 Statement of Compliance - Restriction of Hazardous Substances

This document is a statement of compliance with the EU Directive 2015/863/EU, Restriction of Hazardous Substances (RoHS 3). This document lists Opto 22 products that comply with the substance restrictions of the RoHS 3 directive.

CE Declaration: Low Voltage

This document is the Manufacturer's Declaration for the listed products as mentioned in the attachment - to which this confirmation refers - that they are in accordance with the mentioned European, international and/or national standards and regulations.

SNAP-PAC-EB1 Brain Firmware

This download contains current firmware for the SNAP-PAC-EB1 and SNAP-PAC-EB1-FM brains. Current firmware for all SNAP PAC brains and controllers is available in a single download here.

NOTE: Opto 22 recommends that you always use the most recent release of PAC Manager. Depending on the shipment date or the version number of the firmware currently installed on your SNAP PAC controller, older versions of PAC Manager cannot install certain levels of firmware:
  • Effective April 2, 2018, some SNAP PAC controllers and brains have new flash components. These units shipped with firmware R9.5g (or higher) and new bootloader firmware. PAC firmware versions R9.5f and lower are not compatible with the new component. If you inadvertently install firmware R9.5f or lower on one of these units, you can recover by using the Failsafe Bootloader Mode to install firmware R9.5g or higher.
    • For more information about the new flash component, see KB87213.
    • For details on Failsafe Bootloader Mode, see "Replacing Damaged Firmware" in the PAC Manager User's Guide (form 1704).
See the README document for information on changes and fixes in the current version of this product's firmware.

Video: SNAP PAC System Overview

This overview describes the four integrated components of the SNAP PAC system: software, controllers, brains and I/O. This hardware and software system is designed for industrial control, remote monitoring and data acquisition.

Video: Dual Ethernet Interfaces: Controllers vs. Brains

A quick overview of Dual Ethernet Interfaces: Controllers vs. Brains.

Video: I/O Solutions for Temperature Monitoring

A quick overview on I/O Solutions for temperature monitoring.

Video: Webinar: Controller Redundancy in PAC Control 9

Learn how to implement controller redundancy in SNAP PAC systems.

Playlist: Opto 22 I/O for Allen-Bradley

Learn about Opto 104AB using this playlist of videos.

PID: Reaction Curve Tuning for Interactive PID algorithms

Tune your real-world PID control loop with this graphical tuner. Plug in your data and get calculated P, I, and D values, plus scan rate.

SNAP PAC Networking

Learn the basics about dual ports, redundancy, segmenting, and daisy chaining of SNAP-PAC networking in this interactive demo.