Introduction to S7-1200

S Family

Memory Management

S7-1200

The S family provides a variety of signal modules and signal boards for expanding the capabilities of the CPU.

Scan time

Operating Mode of CPU

CPU Operating Modes

S Data Types

S Memory Type

Input addressing

Output addressing

Memory Addressing

Data Block

Data Block (DB)

DB Addressing

Addressing Examples

OB, FC, FB, DB

Organization Block OBs control the execution of the user program. Each OB must have a unique OB number. Some default OB numbers are reserved below 200. Other OBs must be numbered 200 or greater. OBs cannot call each other or be called from an FC or FB. Only a start event, such as a diagnostic interrupt or a time interval, can start the execution of an OB. The CPU handles OBs according to their respective priority classes, with higher priority OBs executed before lower priority OBs. The lowest priority class is 1 (for the main program cycle), and the highest priority class is 27 (for the time-error interrupts)

System Clock Memory

Portal and project view

Component of the project view

Project Tree