Security; Configuration - Siemens SIMATIC NET CP 243-1 Technical Manual

Communications processor for industrial ethernet

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09/02

2.3

Security

2.3.1

The CP 243-1 configuration is stored in the S7-200 CPU as non-volatile data. The

validity of the configuration is ensured using a CRC mechanism.

When a CP 243-1 configuration is stored, STEP 7 Micro/WIN 32 calculates a CRC

checksum. This checksum is stored together with the configuration. When the CP

243-1 reads out the configuration, it checks this checksum and in this way can rec-

ognize unintentional changes to the stored configuration data.

This CRC mechanism can also be disabled. The configuration can then be

changed either manually or from an S7-200 user program.

Attention

The CP 243-1 cannot completely check the configuration data for consistency with

regard to intentional and unintentional changes after the CRC check has been

switched off. In this case, therefore, there is no guarantee whatsoever that the

CP or the components connected in the network will function correctly.

Attention

The CP 243-1 recognizes that the CRC is disabled when a certain byte in its con-

figuration is set to a particular value. If precisely this value should happen to be set

in the configuration, either intentionally or unintentionally, the CRC check will be

disabled. Therefore, it is strongly advised that the configuration be generated with

the Ethernet Wizard integrated in the STEP 7 Micro/WIN 32, and that the S7-200

program be checked for memory operations running in the data area in which the

CP 243-1 configuration data are stored.

CP 243-1

J31069-D0428-U001-A1-7618

Features and functions

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