Siemens S7-300 appendix Runtimes that change while the program is running

Appendix

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

A.1.4 Runtimes that change while the program is running

Runtimes that change while the program is running

If you have created a user program that has been fine-tuned in relation to certain processing times, please note the following points if you are using a CPU 31xC/31x:

•the program will run much faster on the CPU 31xC/31x.

•Functions that require MMC access (e.g. system start-up time, program download in RUN, return of DP station, etc), may sometimes run slower on the CPU 31xC/31x.

A.1.5 Converting the diagnostic addresses of DP slaves

Converting the diagnostic addresses of DP slaves

If you are using a CPU 31xC/31x with DP interface as the master, please note that you may have to reassign the diagnostic addresses for the slaves since the changes to the DPV1 standard sometimes require two diagnostic addresses per slave.

•The virtual slot 0 has its own address (diagnostic address of the station proxy). The module status data for this slot (read SSL 0xD91 with SFC 51 "RDSYSST") contains IDs that relate to the entire slave/station, e.g. the station error ID. Failure and restoration of the station are also signaled in OB86 on the master via the diagnostic address of the virtual slot 0.

•At some of the slaves the interface module is also modeled as a separate virtual slot (for example, CPU as an intelligent slave or IM153), and a suitable separate address is assigned to virtual slot 2.

The change of operating status is signaled in the master's diagnostic interrupt OB 82 via this address for CPU 31xC-2DP acting as an intelligent slave.

Note

Reading diagnostics data with SFC 13 "DPNRM_DG":

The originally assigned diagnostics address still works. Internally, STEP 7 assigns this address to slot 0.

When using SFC51 "RDSYSST", for example, to read module status information or module rack/station status information, you must also consider the change in slot significance as well as the additional slot 0.

CPU 31xC and CPU 31x, Technical data	A-5
Manual, Edition 08/2004, A5E00105475-05