Bosch CL550 Manual page 38

Power Supply Module
4–12
NT1, NT2, NT3 and NT24
The remanence cannot be guaranteed completely because after turning off
the power supply units, the voltage necessary for the backup of the reman-
ent data cannot be kept alive.
With the help of backup commands, a limited remanence, managed by the
user, can be used:
D Cyclical backups secure the remanent areas in each I/O state; for further
information, please refer to "PLC and CL550 Programming and Oper-
ation, Software Manual".
D Backup on demand secures the remanent areas upon request by PLC
instructions; for further information, please refer to "PLC and CL550 Pro-
gramming and Operation, Software Manual".
. When using the backup commands for remanent areas, the data in the
static RAM always corresponds to the latest storage procedure. I.e.
that in case of a, for example, cyclic backup, the data does not come
from the current but the last completed PLC cycle.
1070 072 263-101 (01.08) GB