Glossary
Glossary-11
ET 200S Interface Module IM 151/CPU
A5E00058783-01
Startup
RESTART mode is activated during the transition from STOP mode to RUN
mode.
Can be triggered by the mode selector or after power on or an operator action on
the programming device. In the case of the ET 200S a restart is carried out.
STEP 7
Programming language for developing user programs for SIMATIC S7 PLCs.
Subscriber
A recipient in direct communication
See
Direct Communication
SYNC
This is a control command of the DP master to a group of DP slaves.
By means of the SYNC control command, the DP master causes the DP slave to
freeze the current statuses of the outputs. In the subsequent frames, the DP
slave stores the output data, but the statuses of the outputs remain unchanged.
After each new SYNC control command, the DP slave sets the outputs that it
has saved as output data. The outputs are not cyclically updated again until the
DP master sends the UNSYNC control command.
System Diagnostics
System diagnostics is the term used to describe the detection, evaluation and
indication of errors which occur within the programmable controller. Examples of
such errors are program errors or module failures. System errors can be
indicated by means of LEDs or in
STEP 7
.
System Function
A system function (SFC) is a function integrated in the operating system of the
CPU that can be called up in the
STEP 7
user program, if necessary.
System Memory
The system memory is integrated on the central processing unit and
implemented as RAM. The system memory includes the address areas (for
example timers, counters, memory markers, etc.) as well as the data areas (e.g.
communication buffers) required internally by the operating system.
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