6. HX3040 Redundancy
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Figure 6-4. Redundancy Machine State
The following sections describe all these transitions as well as the causes that can trigger them. To
correctly interpret the operation of this state machine, notice the following rules and sequences:
Transitions that originate from the same state should be evaluated in the sequence given by the
transition number. For example, transitions, 3, 4, 5 and 6 arise from the Starting state. In this
example, the CPU first evaluates transition 3, then 4, 5, and finally 6. If the transition 3 is
triggered, transitions 4, 5 and 6 and will not be evaluated.
Within a particular subsection, several conditions can trigger a transition. Such conditions should
be evaluated in the order they appear in the subsection. By the moment any of that become true,
the transition arises. If a condition causes the transition, the next conditions will not be evaluated.
The transitions occur in both situations of MainTask (STOP and RUN).
There are several cases in which the commands available on the menu of the CPU display cause
transitions. However, there are alternative internal commands, which are the derived from this
CPU or the other CPU (via redundancy internal link). For further details, see Diagnostics,
Commands and User Data Structure. Although these alternative commands are not mentioned in
the following subsections, be aware that they can cause the same transitions as the commands,
which are available in the display menu.
The Reset Origin command removes the application; thus, the redundancy state is removed from
the display.
Transition 1
– Non-Configured to Starting
There is a prior configuration request by the moment the CPU entered in Non-Configured state.
This happens in the CPU startup and also in other situations, described in the following
subsections
There is a request for the STAND-BY command during the Non-Configured state. Such situation
requires a manual configuration. Typically, the user requests the STAND-BY control after
repairing flaws that previously led this CPU to a Non-Configured or Inactive state.
Transition 2
– Non-Configured to Inactive
There are some software exceptions in the current CPU (watchdog, access violation, illegal
instruction).
Non-
Configured
Starting
Standby
Active
Inactive
1
4
5
6
7
8
9
10
11
12
13
2
3