Siemens Simatic S7 Series

PLC device configuration
6.1 Configuring the operation of the PLC system
S7-200 SMART
System Manual, 09/2015, A5E03822230-AC
123
Data retention after CPU power interruption
The CPU performs the following actions regarding retentive memory at power down and
power up:
●
At power down:
The CPU saves the memory ranges designated as retentive to permanent memory.
●
At power up:
The CPU first clears V, M, C, and T memory, copies any initial values from the data block
to V memory, and then copies the saved retentive values from permanent memory to
RAM.
S7-200 SMART CPU memory addresses for retentive ranges
Data type
Desc.
CPU CR40
CPU CR60
CPU SR20
CPU ST20
CPU SR30
CPU ST30
CPU SR40
CPU ST40
CPU SR60
CPU ST60
V Data Memory VB0-
VB8191
VB0-
VB8191
VB0-VB8191 VB0-VB12281 VB0-VB16383 VB0-VB20479
T Timers T0-T31,
T64-T95
T0-T31,
T64-T95
T0-T31,
T64-T95
T0-T31,
T64-T95
T0-T31,
T64-T95
T0-T31,
T64-T95
C
Counters
C0-C255
C0-C255
C0-C255
C0-C255
C0-C255
C0-C255
M
Flag bits
MB0-MB31
MB0-MB31
MB0-MB31
MB0-MB31
MB0-MB31
MB0-MB31