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Entry type: FAQ Entry ID: 23369901, Entry date: 02/16/2011

How do you parameterize the communication resources of S7-300 CPUs so that WinCC stations and S7-300 stations do not have connection failures?

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If you need multiple OS connections to an S7-300, then for the S7-300 you must set the number of connections accordingly in the hardware configuration (HW Config). You need these settings because the communications resources are restricted.

You normally have to parameterize the connection resources for all S7-300 CPUs except CPU-318. There are sufficient connection resources for CPU 318 and the S7-400 CPUs. A detailed list of the S7-300 CPUs for which you can parameterize the connection resources and notes on the possible settings are available in Entry ID 22276718.

The table below describes how to proceed to set the connection resources.

No. Procedure
1 In the SIMATIC Manager you open the Hardware Configuration of the SIMATIC station concerned.
2 Select the CPU in the Hardware Configuration.
3 Right-click to open the CPU's pop-up menu.
4 Open the Object Properties in the pop-up menu.
5 In the Properties dialog you open the "Communication" tab and under "OP Communication:" you set the number of connections to the visualization systems.

Fig. 01

6 Save, compile and load your settings.

Please refer to the notes in the WinCC Online Help under "Communication > SIMATIC S7 Protocol Suite > Configuring the channel > System Parameter > Cyclic read services in AS" with regard to the cyclic read services in the S7-300 modules. Only 4 cyclic read services are permitted in an S7-300 module.

Additional Keywords
Connection failure, Communication clear-down


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