Siemens S7-300 appendix Changed retentive behavior for CPUs with firmware =

Appendix

A.1 Information about upgrading to a CPU 31xC or CPU 31x

A.1.12 Changed retentive behavior for CPUs with firmware >= V2.1.0

Changed retentive behavior for CPUs with firmware >= V2.1.0

For data blocks for these CPUs

•you can set the retentive response in the block properties of the DB.

•Using SFC 82 "CREA_DBL" -> Parameter ATTRIB, NON_RETAIN bit, you can specify if the actual values of a DB should be maintained at POWER OFF/ON or STOP-RUN (retentive DB) or if the start values should be read from the load memory (non-retentive DB).

A.1.13 FMs/CPs with separate MPI address in the central rack of a CPU 315-2 PN/DP / CPU 317

FMs/CPs with separate MPI address in the central rack of a CPU 315-2 PN/DP / CPU 317

All CPUs, except CPU 315-2 PN/DP, CPU 317	CPU 315-2 PN/DP, CPU 317 and CPU 318-2 DP
and CPU 318-2 DP
If there are FM/CPs with their own MPI address in	If there are FM/CPs with their own MPI address
the central rack of an S7-300, then they are in the	in the central rack of an S7-300, then the CPU
exact same CPU subnet as the CPU MPI station.	forms its own communication bus via the
	backplane bus with these FM/CPs, which are
	separated from the other subnets.
	The MPI address of such an FM/CP is no longer
	relevant for the stations on other subnets. The
	communication to the FM/CP is made via the MPI
	address of the CPU.

When exchanging your existing CPU with a CPU 315-2 PN/DP / CPU 317, you therefore need to:

•replace the CPU in your STEP 7 project with the CPU 315-2 PN/DP / CPU 317.

•Reconfigure the OPs. The control and the destination address must be reassigned (= the MPI address of the CPU 315-2 PN/DP / CPU 317 and the slot of the respective FM)

•Reconfigure the project data for FM/CP to be loaded to the CPU.

This is required for the FM/CP in this rack to remain "available" to the OP/PG.

CPU 31xC and CPU 31x, Technical data	A-9
Manual, Edition 08/2004, A5E00105475-05