OPTO 22 SNAP-PAC-EB1 User manual

SNAP PAC BRAINS USER’S GUIDE
SNAP-PAC-EB1
SNAP-PAC-EB2
Form 1690-070504—May 2007
43044 Business Park Drive • Temecula • CA 92590-3614
Phone: 800-321-OPTO (6786) or 951-695-3000
Fax: 800-832-OPTO (6786) or 951-695-2712
www.opto22.com
Product Support Services
800-TEK-OPTO (835-6786) or 951-695-3080
Fax: [phone]
Email: suppor[email protected]
Web: support.opto22.com

SNAP PAC Brains User’s Guide
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SNAP PAC Brains User’s Guide
Form 1690-070504—May 2007
Copyright © 2007 Opto 22.
All rights reserved.
Printed in the United States of America.
The information in this manual has been checked carefully and is believed to be accurate; however, Opto 22 assumes no
responsibility for possible inaccuracies or omissions. Specifications are subject to change without notice.
Opto 22 warrants all of its products to be free from defects in material or workmanship for 30 months from the
manufacturing date code. This warranty is limited to the original cost of the unit only and does not cover installation, labor, or
any other contingent costs. Opto 22 I/O modules and solid-state relays with date codes of 1/96 or later are guaranteed for life.
This lifetime warranty excludes reed relay, SNAP serial communication modules, SNAP PID modules, and modules that
contain mechanical contacts or switches. Opto 22 does not warrant any product, components, or parts not manufactured by
Opto 22; for these items, the warranty from the original manufacturer applies. These products include, but are not limited to,
OptoTerminal-G70, OptoTerminal-G75, and Sony Ericsson GT-48; see the product data sheet for specific warranty
information. Refer to Opto 22 form number 1042 for complete warranty information.
Cyrano, Opto 22 FactoryFloor, Optomux, and Pamux are registered trademarks of Opto 22. Generation 4, ioControl, ioDisplay,
ioManager, ioProject, ioUtilities, mistic, Nvio, Nvio.net Web Portal, OptoConnect, OptoControl, OptoDataLink, OptoDisplay,
OptoOPCServer, OptoScript, OptoServer, OptoTerminal, OptoUtilities, PAC Control, PAC Display, PAC Manager, PAC Project,
SNAP Ethernet I/O, SNAP I/O, SNAP OEM I/O, SNAP PAC System, SNAP Simple I/O, SNAP Ultimate I/O, and SNAP Wireless LAN
I/O are trademarks of Opto 22.
ActiveX, JScript, Microsoft, MS-DOS, VBScript, Visual Basic, Visual C++, and Windows are either registered trademarks or
trademarks of Microsoft Corporation in the United States and other countries. Linux is a registered trademark of Linus
Torvalds. Unicenter is a registered trademark of Computer Associates International, Inc. ARCNET is a registered trademark of
Datapoint Corporation. Modbus is a registered trademark of Schneider Electric. Wiegand is a registered trademark of Sensor
Engineering Corporation. Nokia, Nokia M2M Platform, Nokia M2M Gateway Software, and Nokia 31 GSM Connectivity
Terminal are trademarks or registered trademarks of Nokia Corporation. Sony is a trademark of Sony Corporation. Ericsson is a
trademark of Telefonaktiebolaget LM Ericsson.
All other brand or product names are trademarks or registered trademarks of their respective companies or organizations.

SNAP PAC Brains User’s Guide iii
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Table of Contents
Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
About SNAP PAC Brains. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
I/O Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
PAC Project Software Suite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Other Communication Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
About this Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Other Documents You May Need . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
For Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Chapter 2: Installing a SNAP PAC Brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
What You Will Need. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Installing Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Installing Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Installing Modules on the Rack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Removing a Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Installing the Brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
What’s Next? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Chapter 3: System Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Communication Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Simultaneous Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Accessing SNAP PAC Brains Over the Internet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Choosing Communication Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
System Architecture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
SNAP PAC Brains as Part of a Distributed SNAP PAC System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
SNAP PAC Brain as an Independent I/O Processor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

SNAP PAC Brains User’s Guide
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Networking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Connecting the Brain Directly to a PC or Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Attaching the Brain to an Existing Ethernet Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Using the Brain in an Independent Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Using SNAP PAC Brain Network Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Correct Connections for Daisy-Chaining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Incorrect Network Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
LEDs and Network Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
SNAP PAC Brain Comparison Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Feature Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Chapter 4: Maintenance and Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Maintaining the SNAP PAC Brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Backup Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Changing the Brain’s IP Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Resetting the Brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Loading New Firmware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Setting Time and Date . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Blink Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Troubleshooting the SNAP PAC Brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Getting Device and Firmware Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Communicating with the Brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Pinging the Brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Accessing the Brain with PAC Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Solving Network Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Additional Troubleshooting Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Making Sure the Brain is in Normal Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
TCP Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

SNAP PAC Brains User’s Guide 1
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Chapter 1
1: Introduction
About SNAP PAC Brains
SNAP PAC brains are powerful and versatile I/O and communications processors for your SNAP PAC
System™. Designed primarily to work in distributed systems controlled by a SNAP PAC S-series or
R-series controller, SNAP PAC brains provide local intelligence that frees the controller for supervisory
tasks.
Two SNAP PAC brains are available: the SNAP-PAC-EB1 and the SNAP-PAC-EB2. They are identical
in their functions and features except that the SNAP-PAC-EB1 provides high-speed digital functions
and analog ramping. The SNAP-PAC-EB2 does not offer high-speed digital functions or analog
ramping. For a complete list of brain features, see page 18.
I/O Processing
As an I/O processor, the SNAP PAC brain provides the local intelligence to independently handle
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 SNAP PAC
controller is lost.
Each SNAP PAC brain mounts on a SNAP PAC rack with up to 4, 8, 12, or 16 SNAP I/O™ modules.
Each module provides from 1 to 32 I/O points, depending on the module.
SNAP PAC brains support all the SNAP I/O analog, digital, serial, and special-purpose 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, to accommodate the required mix of signals
at any location.
For more information on mounting racks, see Opto 22 form #1684, the SNAP PAC Racks Data Sheet.
For more information on I/O modules, visit our website at www.opto22.com.
Communications
In addition to I/O processing, SNAP PAC brains communicate over a standard 10/100 Mbps Ethernet
network. Each SNAP PAC 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

ABOUT SNAP PAC BRAINS
SNAP PAC Brains User’s Guide
2
installed in a multi-drop (daisy-chain) configuration, extending the control network without the
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.
SNAP PAC brains support 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.
PAC Project Software Suite
SNAP PAC brains are primarily designed for use with a SNAP PAC programmable automation
controller. The controller runs a control program, called a strategy, which you develop using PAC
Project™ software.
The PAC Project software suite comes in two forms, Basic and Professional:
• PAC Project Basic, which is included in the purchase of a SNAP PAC controller, consists of
control programming, human-machine interface (HMI) creation, and configuration software.
• PAC Project Professional is available for purchase and adds OptoOPCServer™for OPC
communications, OptoDataLink™for database connectivity, and additional features.
For more information about PAC Project, see form #1699, the PAC Project Data Sheet, available on our
website, www.opto22.com.
Other Communication Methods
In addition to using a SNAP PAC controller with PAC Project software, you can communicate with
SNAP PAC brains using Modbus®/TCP, SNMP for network management, FTP for the brain’s built-in file
system, SMTP (email client), and Opto 22’s own memory-mapped OptoMMP protocol.
Communication with OPC 2.0-compliant clients is available through OptoOPCServer.
•For Modbus/TCP, see Opto 22 form #1678, the Modbus/TCP Protocol Guide.
•For SNMP, FTP, and SMTP, see form #1704, the PAC Manager User’s Guide.
•If you are not using PAC Project but want to develop custom software to communicate with the
brain, the OptoMMP developer toolkit is available for free on our website, www.opto22.com.
The OptoMMP Communication Toolkit includes ActiveX components and C++ classes, so you
can use programming tools such as Visual Basic or Visual C++ to communicate with the brain.
See form #1465, the OptoMMP Protocol Guide, for more information.
•For OPC connectivity, use OptoOPCServer, available either as part of PAC Project Professional or
for separate purchase. See our website for more information.

CHAPTER 1: INTRODUCTION
SNAP PAC Brains User’s Guide 3
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About this Guide
This guide shows you how to install and use SNAP PAC brains. This guide assumes that you have
some familiarity with TCP/IP and Ethernet networking. If you are not familiar with these subjects, we
strongly suggest you consult commercially available resources to learn about them before
attempting to install or use SNAP PAC brains.
The following sections are included in this user’s guide:
Chapter 1: Introduction—information about the guide and how to reach Opto 22 Product
Support.
Chapter 2: Installing a SNAP PAC Brain—quick-start steps to get SNAP PAC brains up and
running quickly.
Chapter 3: System Architecture—conceptual information on networking and communicating
with SNAP PAC brains, and brain specifications.
Chapter 4: Maintenance and Troubleshooting—changing IP addresses, resetting the brain to
factory defaults, and upgrading firmware; blink codes and other troubleshooting assistance.
Other Documents You May Need
See the following additional guides for the information listed. All guides are available on the Opto 22
website, www.opto22.com; some are included on the CD that came with the SNAP PAC brain.
For this information See this guide Form #
Assigning IP address, loading new firmware, etc. PAC Manager User’s Guide 1704
Designing flowchart-based control programs for
the system (requires a SNAP PAC S-series or
R-series industrial controller)
PAC Control User’s Guide 1700
PAC Control Command Reference 1701
PAC Control Commands Quick Reference Card 1703
Communicating with SNAP PAC brains using OPC OptoOPCServer User’s Guide 1439
Connecting the SNAP PAC System with databases OptoDataLink User’s Guide 1705
Communicating with SNAP PAC brains using Mod-
bus/TCP Modbus/TCP Protocol Guide 1678
Programming your own applications for SNAP PAC
brains using the OptoMMP Communication Toolkit
or the OptoMMP memory-mapped protocol
OptoMMP Protocol Guide 1465

FOR HELP
SNAP PAC Brains User’s Guide
4
For Help
If you have problems installing or using SNAP PAC brains and cannot find the help you need in this
guide or on our website, contact Opto 22 Product Support.
Phone: 800-TEK-OPTO (835-6786)
951-695-3080
(Hours are Monday through Friday,
7 a.m. to 5 p.m. Pacific Time)
Fax: [phone]
Email: suppor[email protected]
Opto 22 website: www.opto22.com
When calling for technical support, be prepared to provide the following information about your
system to the Product Support engineer:
•Software and version being used
•Brain and controller firmware version (as applicable)
•PC configuration (type of processor, speed, memory, and operating system)
•A complete description of your hardware and operating systems, including:
– loader and firmware versions for the brain, and date code (available through PAC Manager;
see page 26.)
– IP addresses and net masks for devices on the system
– type of power supply
– third-party devices installed (for example, barcode readers)
•Specific error messages seen
NOTE: Email messages and
phone calls to Opto 22
Product Support are
grouped together and
answered in the order
received.

SNAP PAC Brains User’s Guide 5
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Chapter 2
2: Installing a SNAP PAC Brain
If you already know how you will use the SNAP PAC brain and want to get it running quickly, follow
the sections in this chapter.
To learn about communication options and networking, start on page 9. Specifications are listed on
page 17.
What You Will Need
You’ll need the following items to install a SNAP PAC brain:
•PC running Microsoft®Windows®2000 or higher, with a 10/100 MB Ethernet adapter card, the
TCP/IP protocol installed, and a valid IP address, on the same subnet as the brain. (For more
information, see “Networking” on page 13.)
•Standard Ethernet cable for direct connection to the PC, or an available connection to a
standard 10BASE-T or 100BASE-TX Ethernet network.
•SNAP PAC brain (See page 18 for a chart comparing models.)
•SNAP PAC mounting rack and SNAP I/O modules chosen for your application.
•A SNAP-PS5 or SNAP-PS5U power supply or other 5 VDC power supply (-0/+0.1 VDC at 4.0 A)
applied to the rack. (Additional power may be required for SNAP I/O modules depending on
the number and type of modules used. See the module data sheets on our website,
www.opto22.com, for information.)
Installing Software
In your CD-ROM drive, insert the CD that came with the brain. The installation wizard should start
automatically. If it doesn’t, use Windows Explorer to navigate to your CD-ROM drive and then
double-click setup.exe. Follow directions to install the software.

INSTALLING HARDWARE
SNAP PAC Brains User’s Guide
6
Installing Hardware
Assemble the rack and power supply according to the directions that came with them.
Installing Modules on the Rack
Modules snap into place in the row of connectors on the rack. Each module connector has a number.
NOTE: Any type of module can be placed in any position on the rack. Check module data sheets for power
requirements and any quantity limitations.
1. Place the rack so that the module connector numbers are right-side up, with zero on the left.
2. Position the module over the module connector, aligning the small slot at the base of the
module with the retention bar on the rack.
3. With the module correctly aligned
over the connector, push on the
module to snap it into place.
When positioning modules next to
each other, be sure to align the male
and female module keys (shown in
the detailed view in the illustration at
right) before snapping a module into
position.
Modules snap securely into place and
require a special tool (provided) for
removal. To remove a module, see
page 7.
Module
position zero Module connectors
Brain connector Retention bar

CHAPTER 2: INSTALLING A SNAP PAC BRAIN
SNAP PAC Brains User’s Guide 7
7
4. (Optional) As shown in the photo at right,
use standard 4-40 x 1/2 truss-head Phillips
hold-down screws to secure both sides of
each module.
CAUTION: Do not over-tighten screws.
5. Plug the wiring connector into each
module to attach modules to the devices
they monitor.
Wiring diagrams are in the module’s data
sheet.
Removing a Module
1. If the modules are held in place with
screws, remove them.
2. Holding the SNAP module tool
(provided) as shown in the illustration at
right, insert it into the notch at the base
of the module.
3. Squeeze the module tool against the
module to open the release latch, and
pull straight up on the module to
remove it.
4. Continue with “Installing the Brain” on
page 8.

WHAT’S NEXT?
SNAP PAC Brains User’s Guide
8
Installing the Brain
1. Remove the brain from its packaging.
2. Turn off power to the rack assembly.
3. Align the brain connector with the mating
connector on the mounting rack.
4. Seat the brain onto the connector and use
the hold-down screw to secure the brain in
position. Do not overtighten.
5. Using Category 5 or superior solid
unshielded twisted-pair cable, connect the
brain in one of the following ways:
– (Recommended for initial configuration)
Connect to a PC directly, using a
standard Ethernet cable.
– Connect to a standard 10BASE-T or 100BASE-TX Ethernet network that has a PC on the
same subnet as the brain and does NOT have a Dynamic Host Configuration Protocol
(DHCP) server.
Maximum cable or segment length is 100 meters; minimum cable length is one meter.
6. Before turning on power to the rack, follow instructions in Opto 22 form #1704, the PAC
Manager User’s Guide, to assign an IP address to the brain.
This guide is in Adobe Acrobat PDF format on the CD that came with the brain and is also
available from our website, www.opto22.com.
What’s Next?
To start configuring I/O points, see instructions the PAC Control User’s Guide, form #1700. (If you are
not using PAC Control, follow configuration steps in the PAC Manager User’s Guide.)
To learn more about SNAP PAC brain capabilities and network options, see Chapter 3: System
Architecture. If you are planning to install multiple brains in a daisy-chain configuration, see “Using
SNAP PAC Brain Network Interfaces” on page 15.
To use OLE for process control (OPC) with SNAP PAC brains, purchase the OptoOPCServer and see
Opto 22 form #1439, the OptoOPCServer User’s Guide.
To communicate with SNAP PAC brains using Modbus/TCP, see form #1678, the Modbus/TCP Protocol
Guide.
To program your own applications to communicate with the SNAP PAC brain, see Opto 22 form
#1465, the OptoMMP Protocol Guide.

SNAP PAC Brains User’s Guide 9
9
Chapter 3
3: System Architecture
This chapter explains how to use SNAP PAC brains in an Ethernet network and how to communicate
with them. It includes information on:
Communication Options
SNAP PAC brains communicate using TCP/IP or UDP/IP over a wired or wireless network.
Physical Layer—SNAP PAC brains communicate over a 10- or 100-Mbps wired Ethernet link.
Transport Layer—The key to the SNAP PAC brain‘s communication flexibility is the transport layer,
Internet Protocol (IP). Both the Transmission Control Protocol (TCP) and the User Datagram Protocol
(UDP) are used with IP.
Application Layer—Because SNAP PAC brains use standard IP for the transport layer, many
communication options are possible in the application layer. After the I/O unit is installed and has an
IP address assigned (see page 8), you can communicate with it using the following methods:
• PAC Control strategies running on a SNAP PAC controller can configure, read, and write to I/O
points on SNAP PAC brains.
• PAC Manager software, in addition to its use for assigning IP addresses, can also be used to
configure I/O points and features, and perform onetime reads and writes.
• Modbus/TCP provides a direct connection with Modbus/TCP hardware or software or
third-party software applications, which can read or write to I/O points on SNAP PAC brains.
•OPC(OLE for Process Control) uses OptoOPCServer to serve data to any OPC 2.0-compliant
application, such as an HMI, which can also read or write to I/O points. OptoOPCServer can be
purchased separately or as part of the PAC Project Professional software suite.
Communication options See below
System architecture See page 12
Networking See page 13
Specifications and feature comparison charts See page 17

COMMUNICATION OPTIONS
SNAP PAC Brains User’s Guide
10
• OptoDataLink exchanges I/O point data with ODBC-compliant databases, including Microsoft
SQL Server, Microsoft Access, MySQL, and others. OptoDataLink can be purchased separately or
as part of PAC Project Professional.
• SMTP (Simple Mail Transfer Protocol) connects a SNAP PAC brain with corporate email servers,
so employees can be emailed or paged if there’s a problem on devices attached to the brain.
•SNMP(Simple Network Management Protocol) makes it possible to monitor devices attached
to SNAP PAC brains just as you would any computer or server on the Ethernet network, using an
SNMP-based enterprise management system such as Computer Associates’ Unicenter®,
Hewlett-Packard’s OpenView®, or IBM’s Tivoli®. When a monitored event occurs, such as a door
left open or a pressure level too high, the brain sends an SNMP trap to the management
system.
•FTP(File Transfer Protocol) can be used to transfer files and data to and from the SNAP PAC
brain, whether to custom applications, enterprise databases, or any file system.
• Custom software applications are easy to develop using our OptoMMP Communication
Toolkit with ActiveX components and C++ classes. They use the OptoMMP protocol, an IEEE
1394-based protocol, to read and write to SNAP PAC brains. For developers not using Microsoft
Windows, our OptoMMP protocol is open and documented.
Simultaneous Communication
In addition to communicating using all the methods listed above, each SNAP PAC brain can also
communicate simultaneously using all of these methods.
The reason lies in the nature of IP. In serial communication, a single data request is sent by one device
to another. The first device must wait for a response before any additional communication can be
carried out. IP, however, can establish multiple simultaneous sessions, so many data requests can be
sent at once without waiting for any individual response. Each request gets a response, but the link
isn’t idle while waiting for responses.
In addition, IP can simultaneously handle multiple requests from multiple devices. A PC can
communicate with all SNAP PAC brains and controllers on the same network—all at the same
time—and multiple PCs can communicate with one SNAP PAC device at the same time.
So, for example, a SNAP PAC brain can respond to directions from a Modbus master, give analog
point data to a technician using PAC Manager, and carry out instructions from a custom C++
application—all at once.
Accessing SNAP PAC Brains Over the Internet
Since SNAP PAC brains are just like any other hardware on the Ethernet network, you can access
them over the Internet in exactly the same way you would access a computer. The details depend on
your network and Internet connection. Consult your system or network administrator or your
Internet Service Provider (ISP) for more information.

CHAPTER 3: SYSTEM ARCHITECTURE
SNAP PAC Brains User’s Guide 11
11
Choosing Communication Methods
How do you need to communicate with SNAP PAC brains to match the tasks your application
requires? Check the following table for help in choosing communication methods and finding out
where to look for more information on them.
This task Can be done using these methods Comments and references
Recommended Alternate
Configure I/O units.
PAC Control (I/O
points only) or PAC
Manager (I/O points
and other functions)
OptoMMP Commu-
nication Toolkit or
OptoMMP protocol
If you are using PAC Control, configure the system in
PAC Control. See the PAC Control User’s Guide.
For the Communication Toolkit or OptoMMP protocol,
see OptoMMP Protocol Guide.
Monitor and control pro-
cesses; acquire data.
PAC Control flow-
chart logic
PAC Manager
Inspect window or
OptoMMP Commu-
nication Toolkit or
OptoMMP protocol
See PAC Control User’s Guide & Command Reference.
CAUTION! Events and reactions set up using alternate
methods are faster than flowchart logic, but be careful if
you use them. They can conflict with PAC Control logic,
because both write to the brain’s memory map. For Com-
munication Toolkit or OptoMMP protocol, see OptoMMP
Protocol Guide.
Give technicians an Opto 22
HMI with alarming and trend-
ing.
PAC Display See PAC Display User’s Guide.
Communicate with Mod-
bus/TCP hardware or soft-
ware.
Modbus/TCP See Modbus/TCP Protocol Guide.
Exchange I/O point data with
third-party software such as
HMIs and databases.
OptoOPCServer for
OPC; OptoDataLink
for databases
Purchase OptoOPCServer or OptoDataLink separately
or as part of PAC Project Professional. See OptoOPC-
Server User’s Guide and OptoDataLink User’s Guide.
Send email or page someone.
Send SNMP trap.
Monitor devices through an
enterprise management sys-
tem.
PAC Control (and
PAC Manager for
configuration)
OptoMMP Commu-
nication Toolkit or
OptoMMP protocol
If you are using PAC Control, configure email using PAC
Manager. See the PAC Manager User’s Guide.
For Communication Toolkit or OptoMMP, see OptoMMP
Protocol Guide.
Write your own software
application to communicate
with the system.
C++ or Active X:
OptoMMP Communi-
cation Toolkit and
brain’s memory map.
Opto 22’s OptoMMP
protocol and brain’s
memory map.
See OptoMMP Protocol Guide.

SYSTEM ARCHITECTURE
SNAP PAC Brains User’s Guide
12
System Architecture
SNAP PAC brains can be used in two ways:
•For distributed intelligence in a larger control system based on a SNAP PAC controller running
PAC Control
•As an independent I/O processor
The following diagrams illustrate these two uses.
SNAP PAC Brains as Part of a Distributed SNAP PAC System
The following diagram shows only basic SNAP PAC System capabilities using free PAC Project Basic
software. For information on additional capabilities, such as communication with OPC clients,
databases, and third-party systems, see form #1696, the SNAP PAC System Data Book.
SNAP PAC S-series controller
running PAC Control strategy
PC used for PAC Display HMI
PC used to develop
PAC Control strategy Distributed SNAP PAC brains and I/O
Ethernet network

CHAPTER 3: SYSTEM ARCHITECTURE
SNAP PAC Brains User’s Guide 13
13
SNAP PAC Brain as an Independent I/O Processor
As the following diagram illustrates, you can communicate with an independent SNAP PAC brain
using Modbus/TCP, the OptoOPCServer (available separately), SNMP, SMTP, or applications you
develop using the free OptoMMP Communication Toolkit or our OptoMMP protocol.
Networking
From a physical standpoint, SNAP PAC brains can be networked in several ways:
•Connected directly to a PC or controller using a standard Ethernet cable
•Attached to an existing TCP/IP Ethernet network
•As part of an independent network built with standard Ethernet hardware
The networking method you use depends on several things, including whether you need control or
data acquisition, the number of PCs and I/O units you are using, the speed and volume of
communication, security requirements, and the availability of an Ethernet network.
As an option in any network, you can install multiple brains in a daisy-chain configuration. See
page 15 for more information.
Custom application using
ActiveX or C++
Any OPC client software,
through OptoOPCServer
(purchase separately)
Third-party HMI
•Wonderware
• Intellution
•Iconics
Modbus/TCP hardware
and software
OptoMMP protocol
Modbus/TCP
Ethernet network

NETWORKING
SNAP PAC Brains User’s Guide
14
Connecting the Brain Directly to a PC or Controller
A direct connection using a standard Ethernet cable connects the SNAP PAC brain with one host,
either a PC or a controller. (A crossover cable is not required for direct connection to a host.) You can
use either Ethernet interface on the brain for the connection. Additional SNAP PAC brains can be
daisy-chained from the first brain using the brain’s second Ethernet network interface, which acts as
a network switch. See “Using SNAP PAC Brain Network Interfaces” on page 15 for more information.
If you need only a small control or monitoring network and have no existing Ethernet network, a
direct connection is ideal. It’s quick, easy, and inexpensive because it requires only cables (no
separate Ethernet switches or routers). It also provides high speed and high security for a small
system.
A direct connection is also useful for assigning an IP address, configuring I/O points, and testing
applications. The direct connection eliminates other variables that could interfere with
communication, so you can focus on maintenance and troubleshooting.
Attaching the Brain to an Existing Ethernet Network
The first rule in attaching SNAP PAC brains to an existing network is to work closely with your system
administrator, who must determine network topology and hardware. Be sure to consider the impact
on your existing network of adding the brains. For best performance, use a 100 Mbps network.
In addition, make sure the system administrator understands that each brain must have a fixed
(static) IP address, whether or not a Dynamic Host Configuration Protocol (DHCP) server is used on
the network. For more information on IP addresses, see the PAC Manager User’s Guide.
Because the SNAP PAC brain has two switched Ethernet interfaces, the brains can optionally be
daisy-chained together. (See “Using SNAP PAC Brain Network Interfaces” on page 15.)
If you need to isolate the control system data from the main network backbone, you can use a router,
network switch, or other gateway device. You can also use a SNAP PAC controller, which has two
independent Ethernet network interfaces: one interface can be connected to the enterprise network,
and the other used for the control system. See Opto 22 form #1696, the SNAP PAC System Data Book,
for more information on network options.
Using the Brain in an Independent Network
The third way SNAP PAC brains can be used is by developing an independent network. An
independent network gives a high level of communication speed and volume, as well as high
security. You may also need a separate network for critical control applications. Again, the choice
depends on your requirements for data transactions, data security, and whether a near-deterministic
system is necessary.
If you are building your own network, remember that each brain must have a fixed IP address. See
the PAC Manager User’s Guide for more information on IP addresses.
If you have no existing Ethernet network, you can use off-the-shelf Ethernet components to build
one. Since Ethernet and TCP/IP are worldwide standards, there are a number of commercially

CHAPTER 3: SYSTEM ARCHITECTURE
SNAP PAC Brains User’s Guide 15
15
available resources for learning about building and maintaining such a network. We strongly
suggest you learn as much as possible about the subject and plan your network carefully before
beginning, in order to get the best performance from your system.
Because SNAP PAC brains have two switched Ethernet network interfaces, you can install them in a
daisy-chain configuration. See the next section for more information.
Using SNAP PAC Brain Network Interfaces
As illustrated conceptually at right, SNAP PAC brains
have two Ethernet network interfaces. Ethernet 1 and
Ethernet 2 are not redundant interfaces; they are
connected by an unmanaged switch.
Ethernet devices are normally networked in a standard
star configuration. If you are using this standard
configuration, connect either Ethernet 1 or Ethernet 2 to
the network. The two interfaces share the same IP
address, and either one will send a BootP request.
As an option, however, the SNAP PAC brain’s two
switched Ethernet interfaces let you use a daisy-chain
configuration for distributed I/O, connecting just one
brain to the network and then connecting subsequent
brains in a chain.
The primary advantage of daisy-chaining is that you save the expense of network routers or switches.
The primary disadvantage is similar to that of a serial network: if communication with one brain is lost,
communication to all brains beyond it on the daisy chain will also be lost.
IMPORTANT: If you choose a daisy-chain configuration, make certain that the brains are connected
correctly. Incorrect connections can produce major problems on the network. Make sure that daisy-chain
connections are made in a simple open-ended chain, as shown in the diagram on the following page.
Unmanaged switch
Brain
Unmanaged switch
Ethernet 1 Ethernet 2

NETWORKING
SNAP PAC Brains User’s Guide
16
Never connect SNAP PAC brains in a loop or ring. For example, do not connect both ends of the
chain to the same switch, nor to different switches on the same network. As a rule, do not connect
the second Ethernet interface on the last brain in the chain to any other device.
NOTE: There is one exception to this rule: you can connect the network in a loop if at least one switch in the
loop supports STP/RSTP (Spanning Tree Protocol/Rapid Spanning Tree Protocol) and has that feature
enabled.
Connection from network,
controller, or PC to brain
Daisy-chain connections
Leave the 2nd
interface on the last
brain unconnected.
NOTE: Connection
from a PC does not
require a crossover
cable.
Correct Connections for Daisy-Chaining
Incorrect Network Connections
Ethernet switch
Ethernet switch
Ethernet switch