SNAP PAC Redundancy
Option Kit
PA G E
1
DATA SHEET
Form 1901-100331
SNAP PAC Redundancy Option Kit
Opto 22 • 43044 Business Park Drive • Temecula, CA 92590-3614 • www.opto22.com
SALES 800-321-6786 • 951-695-3000 • FAX 951-695-3095 • sales@opto22.com • SUPPORT 800-835-6786 • 951-695-3080 • FAX 951-695-3017 • support@opto22.com
© 2010 Opto 22. All rights reserved. Dimensions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
Features
Standalone arbiter monitors and controls the active and
backup status of redundant controllers
Redundancy power switch controlled by the arbiter
enables remote rebooting of the controllers
No other special equipment is required
PAC Redundancy Manager provides quick and intuitive
configuration and monitoring
Description
The SNAP PAC Redundancy Option Kit, part number
SNAP-PAC-ROK, provides you the tools you need to develop a
control system with an increased level of reliability that can survive
single points of failure and improve your system’s mean time
between failures (MTBF). In the unlikely event that a controller were
to fail for whatever reason, a second identically configured
controller takes over with almost no down time. This adds yet
another layer of reliability to Opto 22’s extremely reliable distributed
intelligence architecture.
The SNAP PAC Redundancy Option Kit includes a SNAP-PAC-SRA
arbiter, a SNAP-RPSW redundant power switch, and the SNAP
PAC Redundancy Option User’s Guide, form 1831. The PAC
Redundancy Manager is included with PAC Control Professional.
To complete a redundant control system, you will also need the
following items from Opto 22:
• Two S-series PACs (identical part numbers)
• One or more Opto 22 SNAP PAC Ethernet brain-based I/O units
on the same Ethernet network as the controllers
• PAC Project Professional 9.0 or newer installed on a PC con-
nected to the control network
• A PAC Control Professional strategy that makes use of special
redundancy features such as checkpoint blocks and persistent/
redundant variables.
Advantages
When implemented in a redundant system, the Redundancy
Option Kit provides a number of advantages, some of which are
unique to Opto 22:
• Either controller can play the role of the active controller or
backup controller. No prior designation is required.
• Either controller can switch its role in the redundancy scheme
at any time.
• No special cables are required. Standard Cat 5 cable connects
the controllers for synchronization.
• No special redundancy controllers are required, just standard
S-series controllers.
• No special software is needed.
• Instead of requiring the entire control program to be synchro-
nized, the developer tags specific data for redundancy and
places checkpoint blocks at precise points in the logic where
synchronization is to occur. This improves system performance
and provides flexibility for the developer.
• The SNAP-RPSW redundancy power switch enables remote
rebooting of the controllers for tasks such as resetting the con-
troller and updating firmware.
SNAP-PAC-SRA Arbiter
The SNAP-PAC-SRA arbiter is a standalone processor that connects
via dedicated RS-485 links to two identically configured
SNAP PAC S-series controllers to control which controller is active
and which is in backup mode. The arbiter does this based on status
information returned by each controller in response to the arbiter’s
periodic heartbeat requests. LEDs on the arbiter indicate system
health.
Part Numbers
Part Description
SNAP-PAC-ROK
SNAP PAC Redundancy Option Kit.
Includes a redundancy arbitration proces-
sor (SNAP-PAC-SRA) and a redundant
power switch (SNAP-RPSW).
SNAP I/O Racks
SNAP-RPSW
SNAP-PAC-SRA
SNAP PAC Redundancy Option Kit
SNAP PAC Redundancy Option Kit
PA G E
2
DATA SHEET
Form 1901-100331
Opto 22 • 43044 Business Park Drive • Temecula, CA 92590-3614 • www.opto22.com
SALES 800-321-6786 • 951-695-3000 • FAX 951-695-3095 • sales@opto22.com • SUPPORT 800-835-6786 • 951-695-3080 • FAX 951-695-3017 • support@opto22.com
© 2010 Opto 22. All rights reserved. Dimensions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
The arbiter is responsible for the following things:
• Maintains the active/backup status of each controller
• Manages synchronization of strategy and control data
• Sends heartbeat requests at regular intervals to each controller
in order to receive status information
• Qualifies the backup controller, which means that the backup
controller is ready to take over as the active controller
• When a controller is disqualified, the arbiter tells the controller
to reset itself
• Using its supply-voltage output, the arbiter drives normally
closed relays in the SNAP-RPSW, thus controlling the power
supply of each controller
SNAP-RPSW Redundant Power Switch
The SNAP-RPSW redundant power switch is a relay device designed
especially for use in an SNAP PAC redundant system. Connected to
the SNAP-PAC-SRA arbiter and both controllers, this switch
responds to the supply-voltage output from the arbiter, which
allows it to reliably restart a controller in order to bring the
controller back up or re-commission the controller after updating
firmware.
PAC Project Software
The SNAP PAC Redundancy Option Kit is designed for use with
SNAP PAC S-series programmable automation controllers.
The controllers run a control program built with PAC Control™
Professional, one component of PAC Project™ Professional software.
PAC Project Professional is available for purchase and includes
PAC Control Professional for developing control programs, PAC
Display Professional for creating human-machine interfaces (HMIs),
PAC Manager for configuring and maintaining SNAP PAC devices,
OptoOPCServer™ for OPC connectivity, and OptoDataLink™ for
database communications.
PAC Control Professional also provides the following tools for you to
use with the Redundancy Option Kit:
•The PAC Redundancy Manager enables you to configure the
arbiter, monitor the devices in a redundant system, install firm-
ware on the arbiter and the controllers, and more. (See picture
below.)
•A checkpoint block tool, which you use to insert a check-
point block in your logic wherever you want synchronization to
occur
•The Persistent/Redundant variable option that desig-
nates whether a variable is replicated to the backup controller
PAC Redundancy Manager
Current system status
Arbiter and controller
management
SNAP PAC Redundancy Option Kit
SNAP PAC Redundancy Option Kit DATA SHEET
Form 1901-100331
PA G E
3
Opto 22 • 43044 Business Park Drive • Temecula, CA 92590-3614 • www.opto22.com
SALES 800-321-6786 • 951-695-3000 • FAX 951-695-3095 • sales@opto22.com • SUPPORT 800-835-6786 • 951-695-3080 • FAX 951-695-3017 • support@opto22.com
© 2010 Opto 22. All rights reserved. Dimensions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
Specifications
SNAP-PAC-SRA
SNAP-RPSW
Power Requirements 5.0–5.2 VDC at 750 mA maximum
Memory 16 MB RAM
Backup battery for real-
time clock
Rechargeable (recharges whenever the arbiter has power). 5-year life when
power is off.
Operating Temperature 0 to 60 °C
Storage Temperature -40 to 85 °C
Humidity 0–95% humidity, non-condensing
Wired Ethernet Net-
work Interface
IEEE 802.3 network, 10Base-T and 100Base-TX. Automatic MDC/MDI-X
crossover (Ethernet crossover cable not required for direct connection to PC).
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 interfaces (2) RS-485 twisted pair(s), with shield
Serial data rates 300 baud to 230.4 Kbaud
Max switch volts 32 VDC
Max switch current 4 amps DC at 70 °C
Operating range VDC
Switch control (normally closed):
Off 8–32 VDC (3 mA–15 mA)
On < = 2 VDC (< 0.5 mA)
SNAP PAC Redundancy Option Kit
SNAP PAC Redundancy Option Kit
PA G E
4
DATA SHEET
Form 1901-100331
Opto 22 • 43044 Business Park Drive • Temecula, CA 92590-3614 • www.opto22.com
SALES 800-321-6786 • 951-695-3000 • FAX 951-695-3095 • sales@opto22.com • SUPPORT 800-835-6786 • 951-695-3080 • FAX 951-695-3017 • support@opto22.com
© 2010 Opto 22. All rights reserved. Dimensions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
System Architecture
In the following simplified illustration of the redundancy
architecture, two SNAP-PAC-S2 controllers are connected via
Ethernet to the same I/O. A SNAP-PAC-SRA arbiter is connected to
both controllers with dedicated RS-485 links. An Ethernet crossover
cable connected to the ENET2 Ethernet ports enables
communication between the controllers. A SNAP-RSPW
redundancy power switch connected to the arbiter controls power
to the controllers. Separate power supplies for the arbiter and each
of the controllers are not shown. For more information on
connecting power, see “Power Connections” on page 6.
PAC Control Pro with Redundancy Manager
Arbiter
RS-485
RS-485
Ethernet crossover
cable connects the
PAC S2s on ENET2
2 PAC S-series
controllers
Redundancy power switch
Power
Power control
Ethernet, Serial, and Power Switch Connections
SNAP PAC brain and I/O
N-TRON Switch
SNAP PAC Redundancy Option Kit
SNAP PAC Redundancy Option Kit DATA SHEET
Form 1901-100331
PA G E
5
Opto 22 • 43044 Business Park Drive • Temecula, CA 92590-3614 • www.opto22.com
SALES 800-321-6786 • 951-695-3000 • FAX 951-695-3095 • sales@opto22.com • SUPPORT 800-835-6786 • 951-695-3080 • FAX 951-695-3017 • support@opto22.com
© 2010 Opto 22. All rights reserved. Dimensions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
SNAP-PAC-SRA RS-485 Serial Connections
Pin Description
–TX/RX–
CCom
+TX/RX+
not used
not used
not used
CTR2, RS-485
serial connector
CTR1, RS-485
serial connector
Arbiter
CTR1
–TX/RX–
CCom
+TX/RX+
CTR2
–TX/RX–
CCom
+TX/RX+
Controller -to-Arbiter Wiring
SNAP-PAC-S2 #1
Serial 1
2TX/RX–
3Com
1TX/RX+
SNAP-PAC-S2 #2
Serial 1
2TX/RX–
3Com
1TX/RX+
CTR1
CTR2
SNAP-PAC-S2 #1
SNAP-PAC-S2 #2
CTR1 and CTR2 Pins
Serial 2
Serial 2
SNAP PAC Redundancy Option Kit
SNAP PAC Redundancy Option Kit
PA G E
6
DATA SHEET
Form 1901-100331
Opto 22 • 43044 Business Park Drive • Temecula, CA 92590-3614 • www.opto22.com
SALES 800-321-6786 • 951-695-3000 • FAX 951-695-3095 • sales@opto22.com • SUPPORT 800-835-6786 • 951-695-3080 • FAX 951-695-3017 • support@opto22.com
© 2010 Opto 22. All rights reserved. Dimensions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
Power Connections
The following diagram shows how power is connected from the power supplies to the
arbiter and redundancy power switch, and from the power switch to the controllers.
red/white wire (+)
black/white wire (–)
SNAP PAC Redundancy Option Kit
SNAP PAC Redundancy Option Kit DATA SHEET
Form 1901-100331
PA G E
7
Opto 22 • 43044 Business Park Drive • Temecula, CA 92590-3614 • www.opto22.com
SALES 800-321-6786 • 951-695-3000 • FAX 951-695-3095 • sales@opto22.com • SUPPORT 800-835-6786 • 951-695-3080 • FAX 951-695-3017 • support@opto22.com
© 2010 Opto 22. All rights reserved. Dimensions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
SNAP-PAC-SRA LEDs
Communication Status LEDs
LED Indicates
LNK Link established with Ethernet network
ACT Ethernet network activity
TX Outgoing serial activity
RX Incoming serial activity
System Status LEDs
LED Indicates
ARB
Arbiter status
Off = arbiter has failed or is not powered; LED2-6 values are undefined
Red = arbiter has failed
Orange = arbiter is starting
Green = arbiter is online
SYS
Controller redundancy status
Red = no controller is active
Orange = one controller is active, with no qualified backup
Green = one controller is active, with a qualified backup
CTR1
Primary controller status
Red = failed
Orange-blinking = backup qualified impaired or not qualified
Orange = backup qualified
Green-blinking = active impaired or becoming active
Green = active nominal
CTR2
Secondary Controller Status
Red = failed
Orange-blinking = backup qualified impaired or not qualified
Orange = backup qualified
Green-blinking = active impaired or becoming active
Green = active nominal
Serial activity
Ethernet activity
Arbiter status
Controller 2 status
System status
Controller 1 status
SNAP PAC Redundancy Option Kit
SNAP PAC Redundancy Option Kit
PA G E
8
DATA SHEET
Form 1901-100331
Opto 22 • 43044 Business Park Drive • Temecula, CA 92590-3614 • www.opto22.com
SALES 800-321-6786 • 951-695-3000 • FAX 951-695-3095 • sales@opto22.com • SUPPORT 800-835-6786 • 951-695-3080 • FAX 951-695-3017 • support@opto22.com
© 2010 Opto 22. All rights reserved. Dimensions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
SNAP-RPSW Redundancy Switch Connectors and LEDs
Power in from Controller 2
power supply
Power in from Controller 1
power supply
Power out to Controller 2
Power out to Controller 1
Turn off controller 2
Turn off controller 1
A green LED indicates a normal “ON” condition.
Power out: Normally on. When off, no power goes to the controller.
Power in: On as long as power is received from the power supply.
Turn off: Normally on. When a 8-32 VDC pulse is received from the arbiter, the SNAP-RPSW switches off power to the
power out terminal, which shuts off the controller. A 2 VDC pulse switches power back on.
NOTE: The arbiter has its own power supply. If power is lost to the arbiter, power continues to be supplied to both
controllers, and the active controller remains in control.
SNAP PAC Redundancy Option Kit
SNAP PAC Redundancy Option Kit DATA SHEET
Form 1901-100331
PA G E
9
Opto 22 • 43044 Business Park Drive • Temecula, CA 92590-3614 • www.opto22.com
SALES 800-321-6786 • 951-695-3000 • FAX 951-695-3095 • sales@opto22.com • SUPPORT 800-835-6786 • 951-695-3080 • FAX 951-695-3017 • support@opto22.com
© 2010 Opto 22. All rights reserved. Dimensions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
Dimensions
SNAP-PAC-SRA and SNAP-RPSW
More About Opto 22
www.opto22.com • Opto 22 • 43044 Business Park Drive • Temecula, CA 92590-3614 • Form 1335-090113
SALES 800-321-6786 • 951-695-3000 • FAX 951-695-3095 • sales@opto22.com • SUPPORT 800-835-6786 • 951-695-3080 • FAX 951-695-3017 • support@opto22.com
© 2010 Opto 22. All rights reserved. Dimensions and specifications are subject to change. Brand or product names used herein are trademarks or registered trademarks of their respective companies or organizations.
Products
Opto 22 develops and manufactures reliable, flexible, easy-to-use
hardware and software products for industrial automation, remote
monitoring, and data acquisition applications.
SNAP PAC System
Designed to simplify the typically complex process of
understanding, selecting, buying, and applying an automation
system, the SNAP PAC System
consists of four integrated
components:
•SNAP PAC controllers
•PAC Project™ Software Suite
•SNAP PAC brains
•SNAP I/O™
SNAP PAC Controllers
Programmable automation controllers
(PACs) are multifunctional, multidomain,
modular controllers based on open standards and
providing an integrated development environment.
Opto 22 has been manufacturing PACs for many years. The latest
models include the standalone SNAP PAC S-series and the rack-
mounted SNAP PAC R-series. Both handle a wide range of digital,
analog, and serial functions and are equally suited to data
collection, remote monitoring, process control, and discrete and
hybrid manufacturing.
SNAP PACs are based on open Ethernet and Internet Protocol (IP)
standards, so you can build or extend a system without the expense
and limitations of proprietary networks and protocols.
PAC Project Software Suite
Opto 22’s PAC Project Software Suite provides full-featured and
cost-effective control programming, HMI (human machine
interface) development and runtime, OPC server, and database
connectivity software to power your SNAP PAC System.
These fully integrated software applications share a single tagname
database, so the data points you configure in PAC Control™ are
immediately available for use in PAC Display™, OptoOPCServer™,
and OptoDataLink™. Commands are in plain English; variables and
I/O point names are fully descriptive.
PAC Project Basic offers control and HMI tools and is free for
download on our website, www.opto22.com. PAC Project
Professional, available for separate purchase, adds OptoOPCServer,
OptoDataLink, options for Ethernet link redundancy or segmented
networking, and support for legacy Opto 22 serial mistic™ I/O units.
SNAP PAC Brains
While SNAP PAC controllers provide central control and data
distribution, SNAP PAC brains provide distributed intelligence for
I/O processing and communications. Brains offer analog, digital,
and serial functions, including thermocouple linearization; PID loop
control; and optional high-speed digital counting (up to 20 kHz),
quadrature counting, TPO, and pulse generation and measurement.
SNAP I/O
I/O provides the local connection to sensors and equipment.
Opto 22 SNAP I/O offers 1 to 32 points of reliable I/O per module,
depending on the type of module and your needs. Analog,
digital, serial, and special-purpose modules are all mixed on
the same mounting rack and controlled by the same processor
(SNAP PAC brain or rack-mounted controller).
Quality
Founded in 1974 and with over 85 million devices sold,
Opto 22 has established a worldwide reputation for high-
quality products. All are made in the U.S.A. at our
manufacturing facility in Temecula, California. Because we
do no statistical testing and each part is tested twice before leaving
our factory, we can guarantee most solid-state relays and optically
isolated I/O modules for life.
Free Product Support
Opto 22’s Product Support Group offers free, comprehensive
technical support for Opto 22 products. Our staff of support
engineers represents decades of training and experience. Product
support is available in English and Spanish, by phone or email,
Monday through Friday, 7 a.m. to 5 p.m. PST.
Free Customer Training
Hands-on training classes for the SNAP PAC System are offered at
our headquarters in Temecula, California. Each student has his or
her own learning station; classes are limited to nine students.
Registration for the free training class is on a first-come, first-served
basis. See our website, www.opto22.com, for more information or
email training@opto22.com.
Purchasing Opto 22 Products
Opto 22 products are sold directly and through a worldwide
network of distributors, partners, and system integrators. For more
information, contact Opto 22 headquarters at 800-321-6786 or
951-695-3000, or visit our website at www.opto22.com.
www.opto22.com
