Address Areas Of The System Memory - Siemens SIMATIC ET 200S Manual

Functions of the IM 151-7 CPU
8.4.3 Address areas
Overview
The system memory of the IM 151-7 CPU id divided into address areas (see the
table below). In your program, you use the appropriate operations to address the
data directly in the respective address area.
Table 8-9
Address area
Process image of the inputs
Process image of the outputs
Memory markers
Timers
Counter
Local data
Data blocks
The Instruction list tells you which address areas are possible with your CPU.
8-20

Address areas of the system memory

At the beginning of each OB 1 cycle, the IM 151-7 CPU
reads the inputs out of the input modules and stores the
values in the process image of the inputs.
During the cycle, the program calculates the values for the
outputs and stores them in the process image of the
outputs. At the end of the OB 1 cycle, the IM 151-7 CPU
writes the calculated output values to the output modules.
This area provides memory for intermediate results
calculated in the program.
Timers are available in this area.
Counters are available in this area.
This memory area records the temporary data of a code
block (OB, FB, FC) during the period in which this block is
being processed.
See Section 8.4.4
Description
ET 200S IM 151-7 CPU Interface Module
A5E00058783-04