Glossary
Cold restart
On CPU startup (e.g. after it is switched from STOP to RUN via the mode selector or with
POWER ON), OB100 (restart) is initially executed, prior to cyclic program execution (OB1).
On restart, the input process image is read in and the STEP 7 user program is executed,
starting at the first command in OB1.
Configuration
Assignment of modules to racks/slots and (for example with signal modules) addresses.
Consistent data
Data that belongs together in terms of its content and must not be separated, is designated
as consistent data.
As an example, the values of analog modules must always be treated as consistent data; i.e.
the value of an analog module must not be corrupted by reading it out at two different times.
Counters
Counters are part of CPU system memory. The content of "counter cells" can be modified by
STEP 7 statements (for example, up/down count.)
Cycle time
The cycle time represents the time a CPU requires for one execution of the user program.
Data block
Data blocks (DB) are data areas in the user program and contain the user data. There are
global data blocks which can be accessed by all code blocks, and instance data blocks
which are assigned to a specific FB call.
Data, static
Static data are data that are used only within a function block. These data are stored in an
instance data block belonging to the function block. Data stored in an instance data block are
retained until the next function block call.
Data, temporary
Temporary data represent local data of a block. They are stored in the L-stack when the
block is executed. After the block has been processed, these data are no longer available.
Diagnostic interrupt
Modules capable of diagnostics report detected system errors to the CPU by means of
diagnostic interrupts.
S7-300 CPU Data: CPU 315T-2 DP
Glossary-2 Manual, 12/2005, A5E00427933-02
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