Functions of the IM 151-7 CPU
8-14
ET 200S IM 151-7 CPU Interface Module
A5E00058783-04
Retentive behavior of the memory objects
The following table shows the retentive behavior of the memory objects during the
individual operating mode transitions.
Table 8-7 Retentive behavior of the memory objects
Memory object
Operating mode transition
POWER
OFF/
POWER ON
STOP →
RUN
Memory re-
set
User program/data (load memory) X X X
Current values of the DBs Can be set in the DB
properties using STEP 7
V5.2 + SP1 (see below)
–
Memory markers, timers and counters
configured as retentive
X X –
Diagnostic buffers, run-time meters X X X
MPI address, transmission rate X X X
x = retentive; – = not retentive
Retentive behavior of a DB in IM 151-7 CPU
For IM 151-7 CPU, you can use STEP 7 (as of V5.2 + SP1) or the SFC 82
“CREA_DBL” (Parameter ATTRIB → Bit NON_RETAIN) to set whether, for
POWER OFF/ON or STOP → RUN, a DB is to
retain the current values (retentive DB) or
adopt the initial values from the load memory (non-retentive DB).
Table 8-8 Retentive behavior of the DBs in IM 151-7 CPU
In the event of a POWER OFF/ON or a CPU restart, the DB is to
Receive the initial values
(non-retentive DB)
Retain the last current values
(retentive DB)
Background:
In the event of a POWER OFF/ON or a CPU
restart (STOP → RUN), the current values
of the DB are not retentive. The DB receives
the initial values from the load memory.
Background:
In the event of a POWER OFF/ON or a CPU
restart (STOP → RUN), the current values
of the DB are retained.
Prerequisite in STEP 7:
The “Non-Retain” checkbox is activated
in the block properties of the DB or
A non-retentive DB was generated with
the SFC 82 “CREA_DBL” and the
associated block attribute (ATTRIB
→
Bit NON_RETAIN).
Prerequisite in STEP 7:
The “Non-Retain” checkbox is not
activated in the block properties of the
DB or
A retentive DB was generated with the
SFC 82.
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