6. Redundancy with NX3030 CPU
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After each compilation, MasterTool sums the redundancy overhead calculated with the parameter
which informs the POU times (NonSkippedPrg and ActivePrg), and verifies is the minimum
looseness parameterized is being obeyed.
E.g.:
ï‚· Parameters configured in the MainTask screen:
o MainTask cycle time: 100 ms
o POUs NonSkippedPrg + ActivePrg estimated time: 10 ms
o Minimum tolerance: 30%
ï‚· calculated Overhead for redundancy: 50 ms
In this case, the total time used is 60ms (10 ms + 50 ms), which consists in 60% of the MainTask
cycle (100ms). This way, the maximum looseness is 40% and the minimum looseness of 30% is
being respected.
ATTENTION:
A compilation error is produced in case the minimum looseness isn’t respected, if it is configured in
the CPU Project Parameters..
ATTENTION:
The compilation being successful or not, MasterTool informs the calculated looseness and the
redundancy overhead predicted on the message window
ActivePrg Program
In this POU the user must create the main application, responsible for its process control. This POU
is called by the main POU (MainPrg), being executed only in the Active CPU.
The user can also create additional POUs (program, function or function block), and call or instance
them inside the ActivePrg POU, in order to structure his program. It’s possible to call functions and
instance function blocks defined in libraries, too.
It must be remembered that all symbolic variables defined in the ActivePrg POU, as the instances of
function blocks, are redundant variables.
Symbolic variables defined in additional POUs from the program type which are called inside the
ActivePrg, are also redundant variables.
ATTENTION:
Variables from the type VAR_TEMP must not be used in the redundant program.
NonSkippedPrg Program
This POU is used for controls which must be executed in both CPUs (PLCA and PLCB),
independent on the redundancy state. This POU is also called by the main POU (MainPrg).
It must be remembered that all symbolic variables defined in the NonSkippedPrg POU, as well as the
function blocks instances, are non-redundant variables.
The user must create additional POUs (program, function or function block), and call or instance
them inside the NonSkippedPrg POU, in order to structure his program. It’s possible to call functions
and instance function blocks defined in libraries, too.
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