ALTUS Nexto Series User Manual

5. CONFIGURATION
5.7. System Performance
In cases where the application has only one MainTask user task responsible for the execution of a single Program type pro-
gramming unit called MainPrg (as in Single Profile), the PLC consumes a certain amount of time for the task to be processed.
At that time we call it as Execution Time.
In an application the average application Execution Time can be known using the MasterTool IEC XE in the Device item
of its Devices Tree as follows:
PLC Logic-> Application-> Task Configuration in the Monitor tab, Average Cycle Time column.
The user must pay attention to the Cycle Time so that it does not exceed 80% of the interval set in the MainTask user task.
For example, in an application where the interval is 100 ms, an appropriate Cycle Time is up to 80 ms. This is due to the fact
that the CPU needs time to perform other tasks such as communication processing, processing of the display and memory card,
and these tasks take place within the range (the remaining 20% of Cycle Time).
ATTENTION
For very high cycle times (typically higher than 300 ms), even that the value of 80% is
respected, it may occur a reduction in the display response time and of the diagnostics key.
In case the 80 percentage is not respected and the running time of the user task is closer or
exceeds the interval set for the MainTask, the screen and the diagnosis button cannot respond
once its priority in the system running is lower than the user tasks. In case an application with
errors is loaded in the CPU, it may be necessary to restart it without loading this application
as shown in the System Log section.
ATTENTION
The CPU’s system logs of the Nexto Series, starting from firmware version 1.4.0.33 now
reloaded in case of a CPU reset or a reboot of the Runtime System, that is, you can view the
older logs when one of these conditions occurs.
5.7.1. I/O Scan Time
For a project that uses digital I/O modules, being them inserted into the bus and declared in the project, the MainTask time
will increase according to the number of modules. The table below illustrates the average time that is added to the MainTask:
Declared Modules in the Bus Added Time in the MainTask Cycle Time (µs)
5 300
10 700
20 1000
Table 155: I/O Scanning Time
In projects that use remote I/Os, for example, using the NX5001 PROFIBUS-DP Master module, the manual of the re-
spective module has to be consulted for information about performance and influences of the module in the execution of user
tasks.
5.7.2. Memory Card
Data transfers involving the memory card is performed by the CPU in the background, as this gives priority to the execution
of user application and communication processing. Thus, the transfer of files to the card may suffer an additional significant
time, depending on the Cycle Time of the user application.
The time required to read/write files on the card will be directly affected by the Cycle Time of the user application since
this application has priority in execution.
Further information about the use of the memory card see Memory Card section.
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ALTUS Nexto Series Specifications

General

Brand	ALTUS
Model	Nexto Series
Category	Computer Hardware
Language	English