Siemens SINUMERIK 840Di Function Manual page 1213

2.5 Linking PLC CPUs to 840D
2.5
2.5.1 General
General
The AS 300 family is used as the PLC for all systems. On the 840 D, the PLC CPU is
integrated into the NCU component as a sub-module. The relevant performance data for
PLC CPUs can be found in the above table or in the SIMATIC catalog.
2.5.2 Properties of PLC CPUs
SINUMERIK 810D/840Di PLC CPUs are based on standard SIMATIC CPUs in the S7300
family. As a result, they generally possess the same functions. Functional deviations are
shown in the table above. Owing to differences in their memory system as compared to the
SIMATIC CPU, certain functions are not available (e.g. save blocks on memory card, save
project on memory card).
Note
With the current SIMATIC CPUs, the PLC is not automatically started after voltage failure
and recovery when a PLC Stop is initiated via software operation. In this instance, the PLC
remains in the Stop state with an appropriate diagnostic entry for safety reasons. You can
start the PLC only via software operation "Execute a restart" or by setting the switch to
"Stop" and then "RUN". This behavior is also integrated in the current versions of the
SINUMERIK PLC.
2.5.3 Interface on 840D with integrated PLC
Physical interfaces
As the 840D system has an integrated PLC, signals can be exchanged between the NCK
and PLC directly via a dual-port RAM.
PLC Basic Program Solution Line (P3 sl)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
Detailed Description
2.5 Linking PLC CPUs to 840D
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