Selecting The Mode Of Operation For The Cpu; Changing The Operating Mode With The Mode Switch - Siemens SIMATIC S7-200 System Manual

4.7

Selecting the Mode of Operation for the CPU

The S7-200 CPU has two modes of operation:
STOP: The CPU is not executing the program. You can download a program or
configure the CPU when the CPU is in STOP mode.
RUN: The CPU is running the program.
The status LED on the front of the CPU indicates the current mode of operation.
You can change the mode of operation by:
Manually changing the mode switch located on the CPU
Using the STEP 7-Micro/WIN 32 programming software and setting the CPU
mode switch to TERM or RUN
Inserting a STOP instruction in your program

Changing the Operating Mode with the Mode Switch

You can use the mode switch (located under the front access door of the CPU) to
manually select the operating mode for the CPU:
Setting the mode switch to STOP mode stops the execution of the program.
Setting the mode switch to RUN mode starts the execution of the program.
Setting the mode switch to TERM (terminal) mode does not change the CPU
operating mode.
If a power cycle occurs when the mode switch is set to either STOP or TERM, the
CPU goes automatically to STOP mode when power is restored. If a power cycle
occurs when the mode switch is set to RUN, the CPU goes to RUN mode when
power is restored.
S7-200 Programmable Controller System Manual
A5E00066097-02
Basic Concepts for Programming an S7-200 CPU
4-25