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Presentation
The Premium Hot Standby offer, compatible with Unity Pro software, ensures
continuity of operation of a Modicon Premium automation platform control system in
the event of failure of:
b
The central processing and communication functions
b
All or part of the I/O system
It is based on the principle of Primary/Standby redundancy with complete redundancy
of the main processing and communication functions, use of shared I/O on the
Ethernet TCP/IP network, the Modbus link and/or redundancy of in-rack I/O
(
single-rack or multi-rack configuration).
Premium Hot Standby redundant architectures offer an optimum solution for
responding to requirements for availability where changeover times are not critical.
They are suitable for processes which can tolerate a lack of control, on the part of the
Premium control unit, lasting a maximum of around one second (typical duration
corresponding to the changeover time from the Primary unit to the Standby unit and
the time it takes the shared I/O on Ethernet to refresh).
It covers all the requirements for availability when the PLC's mission is to monitor
and control an installation in continuous duty, indicate problems to a control station,
and send the supervision manager's control instructions to various locations on an
extensive site.
Examples of areas of application:
b
Building management system for a public site (tunnel, airport, signalling, etc.)
b
Control and monitoring of water treatment or desalination plant
b
Electrical management system
b
Production of hydro-electric power, etc.
Principle
At the heart of the system there are 2 single-rack or multi-rack
(1)
Modicon Premium
configurations, known as the Primary PLC and the Standby PLC. They have
identical hardware and software configurations (identical modules in each rack). The
offer comprises two processor models,
TSX H57 24M
and
TSX H57 44M
,
dedicated
to Hot Standby architectures with Unity Pro software (version
u
3.1
in single-rack
configuration and
u
5.0
in multi-rack configuration).
These double format processors combine the central processing unit and redundant
coprocessor functions in the same housing.
The Primary PLC:
b
Executes the application program and controls the I/O which may be:
v
Field products on the Ethernet network managed by the I/O Scanning service
(
see page 5/32)
v
Field products on the Modbus master link
v
Sensors and actuators connected to the Premium I/O modules on Bus X in a
single-rack or multi-rack configuration
b
Transfers all its data to the Standby PLC via the CPU Sync link at the start of each
scan
In the event of failure of the Primary PLC, the standby system switches over
automatically, taking 1.5 PLC scan cycles, changing over execution of the application
program and control of the I/O to the Standby PLC with an up-to-date data context.
The Ethernet network modules of both Premium configurations managing the field
products exchange their addresses by means of an automatic “IP” and “IP + 1”
address assignment mechanism. This mechanism applies to Modbus link modules
with assignment of the slave addresses “n” and “n + 1”.
Once they have changed over, the “Standby” PLC becomes the “Primary” PLC.
Once the faulty PLC has been repaired and reconnected to the standby system,
it takes the role of the Standby PLC.
(1)
The latest version of
TSX H57 24M/44M
Hot Standby processors incorporates the firmware
for the V2.83 PLC operating system and the Ethernet V2.82 coprocessor which is used to
configure multi-rack Hot Standby applications in Unity Pro V5.0. Up-to-date versions of these
firmware programs are available on our website
www.schneider-electric.com.
Ethernet
Ethernet
I/O
I/O
Ethernet
Ethernet
I/O
I/O
SCADA
Standby
Premium
Ethernet Modbus/TCP
Primary
Premium
Sensors/actuators
CPU Sync link
Field products on Ethernet Modbus/
TCP network (I/O Scanning)
2
to 1
Presentation
Primary Modicon Premium Standby Modicon Premium
CPU Sync link
Modicon Premium automation
platform
0
Hot Standby system
Unity Pro software
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