Table of Contents
Advertisement
Supplementary information
16.15 Cycle and response times of the CPU 410-5H
Table 16- 8
Module type
ET200M: Standard output modules
ET200M: HART output modules
ET200M: F-output modules
Follow the steps below:
● Calculate the overhead from the table. If you use several module types from the table
redundantly, apply the largest overhead.
● Add this to all of the monitoring times calculated so far.
16.15
Cycle and response times of the CPU 410-5H
16.15.1
Cycle time
This chapter describes the decisive factors in the cycle time, and how to calculate it.
Definition of cycle time
The cycle time represents the time that the operating system needs to execute a program,
that is, one OB 1 cycle, including all program sections and system activities interrupting this
cycle.
This time is monitored. The CPU 410-5H has a fixed cycle monitoring of 6 seconds.
Time slice model
Cyclic program processing, and therefore also user program processing, is based on time
slices. To demonstrate the processes, let us presume a global time slice length of exactly
1 ms.
Process image
During cyclic program execution, the CPU requires a consistent image of the process
signals. To ensure this, the process signals are read/written prior to program execution.
During the subsequent program execution, the CPU does not access the signal modules
directly when addressing the input (I) and output (O) address areas. It accesses the CPU's
system memory area containing the image of the inputs and outputs.
272
For the monitoring times with redundant I/O
Overhead in ms
2
10
50
CPU 410-5H Process Automation/CPU 410 SMART
System Manual, 10/2013, A5E32631667-AA
Advertisement
Table of Contents
