Rockwell Automation Allen-Bradley DriveLogix 5730, Руководство пользователя

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1-10 What is DriveLogix5730?
execute the continuous task. While increasing the system overhead
percentage decreases execution time for the continuous task, it does
increase communications performance. However, increasing the system
overhead percentage also increases the amount of time it takes to execute a
continuous task - increasing overall scan time.
The following table shows the ratio between the continuous task and the
system overhead functions:
At the default time slice of 10%, system overhead interrupts the continuous
task every 9 ms (of continuous task time), as illustrated below.
The interruption of a periodic task increases the elapsed time (clock time)
between the execution of system overhead, as shown below.
At this time slice: The continuous tasks runs for: And then overhead occurs for up to:
10% 9 ms 1 ms
20% 4 ms 1 ms
33% 2 ms 1 ms
50% 1 ms 1 ms
TIP: For typical DriveLogix applications, a setting of 20-33% is
recommended.
Legend:
Task executes.
Task is interrupted (suspended).
periodic
1 ms 1 ms
system overhead
9 ms 9 ms
continuous task
0 5 10 15 20 25
elapsed time (ms)
1 ms 1 ms 1 ms 1 ms 1ms
periodic task
1 ms 1 ms
system overhead
9 ms of continuous task time 9 ms of continuous task time
continuous task
0 5 10 15 20 25
elapsed time (ms)