6. HX3040 Redundancy
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General Features
Redundant CPU General Features
Allowed CPUs
HX3040
Redundancy types
Hot-standby
Failure tolerances
The CPU supports, at least, simple failures in doubled equipment in the racks. In
specific cases, it can support multiple failures.
5 redundancy states
- Not-configured: initial state, also considered when the CPU is off or is not executing
the MainTask.
- Starting: temporary status obtained after the Not-configured state, where some
tests will define the next situation (Inactive, Active, Stand-by or back to Not-
configured).
- Inactive: state reached after some given types of failures or programming
maintenance.
- Active: controls the user process.
- Stand-by: ready to switch to Active and control the user process, in case there is
such demand (e.g. Active CPU failure).
Main failures that cause
switchover between the Active
CPU and the Stand-by CPU.
The Stand-by CPU switches to
Active mode. The Active can go
to Inactive or Not-configured.
- Supplying failure.
- CPU (stop in the MainTask execution).
- Failure of both synchronism channels among the CPUs.
Commands that cause
switchover between the CPUs
(Active CPU and Stand-by)
- Commands via CPUs display.
- Commands received from MasterTool Xtorm or from a SCADA system, through the
RTU (local or remote).
- Commands generated by the user application (e.g. Ethernet communication
failure), through the RTU (local or remote).
Main failures, which prevent a
CPU, to go to Stand-by state or
remain in it.
Such failures drive the CPU to a
Not
–Configured or Inactive state.
- Supplying failure.
- CPU (stop in the MainTask execution).
- Failure in one of synchronism channels (A or B).
- Failure in the synchronism service for redundancy data.
- Different project than the one from the Active CPU.
- Firmware version incompatible with the Active CPU.
Commands that drive the CPU
out of the Stand-by state
- Commands via redundant CPUs display.
- Commands received from MasterTool Xtorm or from a SCADA system, through the
RTU (local or remote).
- Commands generated by the user application (e.g. Ethernet communication
failure), through the RTU (local or remote).
Switchover time
- Up to three cycles from the MainTask, depending on the stimulus for state change
(command or failure).
No discontinuities switchover
(bump-less)
- A switchover does not cause discontinuities in the controller outputs, nor in the
inner variables.
Redundancy overhead (MainTask
cycle CPU consuming increased
by redundancy).
- Maximum value automatically calculated by MasterTool and informed to the user,
considering an empty redundant forcing list.
- Typical average value of 15ms for 100 kBytes of redundant data, in a query of 4500
events.
CPU display
Among other diagnostics, shows the redundancy state (Active, Stand-by, Inactive,
Not-configured, Starting).
Through the menu options, it allows switchover commands as well as the transition
between the redundancy states for maintenance purposes.
Redundancy diagnostics
- It indicates failures both in CPUA and CPUB, regardless of their states (Active or
Inactive).
-
It prevents “obscure failures”.
- It allows a quick maintenance, which is essential to get high availability.
Redundancy commands
- It allows the execution of the same CPU display actions, among other commands
(e.g. switchover command).
- It can be executed in the local CPU, or transmitted to the other RTU (remote) via
synchronism channels between the CPUs.
- It can be received through the MasterTool Xtorm or a SCADA system.
- It can be executed through the user application.
Redundancy events
It registers diagnostics and redundancy commands changes, with timestamp,
allowing an investigation of the switchover causes.
IRIG-B, DNP3 and SNTP (Simple
Network Time Protocol)
It allows the events to have a precise timestamp adjusted to the world hour. It also
synchronizes the CPU real time clock for other applications.
MasterTool screens for
Diagnostics, Commands and
Events of Redundancy LOG
MasterTool Xtorm programmer offers special screens for commands and redundancy
diagnostics, as well as to show the redundancy LOGs.
