Siemens Simatic S7-400, Руководство по установке

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Glossary
Glossary-14
Automation System S7-400 Hardware and Installation
A5E00850741-01
System Diagnostics
System diagnostics is the detection, evaluation, and reporting of errors occurring
within the programmable controller. Examples of such errors are: program errors or
failures on modules. System errors can be indicated with LED indicators or by
STEP 7.
System Function (SFC)
An integral programmable function of the CPU operating system. Can be called in
the user program. SFCs are not loaded as part of the program, because they are
part of the operating system. SFCs do not have a memory function, same as FCs.
System Function Block (SFB)
An itegral function block of the CPU operating system. SFBs are not loaded as part
of the program, because they are part of the operating system. Without memory
function, same as SFCs. You need to create instance DBs for these blocks and
load them into the CPU as part of the user program.
System Memory
The system memory is integrated in the CPU and executed in the form of RAM.
The address areas (timers, counters, bit memory, etc.) and data areas required
internally by the operating system (for example, backup for communication) are
stored in the system memory.
T
Terminating resistor
Used to terminate data transfer lines in order to avoid reflections on the bus.
Time-Delay Interrupt
The time-delay interrupt belongs to one of the priority classes in SIMATIC S7-400
program processing. It is generated after expiry of a time started in the user
program. A corresponding organization block is then executed.
Time-Of-Day Interrupt
The time-of-day interrupt belongs to a priotity class in SIMATIC S7-400 program
program execution. It is generated depending on a certain date (or daily) and time
of day (for example, 9:50 or hourly, per minute). A corresponding organization
block is then executed.