Siemens ET 200SP Operating Instructions Manual page 85

● Key length
Length of the pre-shared key in bytes
The following lengths are used depending on the key wrap algorithm.
– For AES-128: 16 bytes
– For AES-256: 32 bytes
● Max. number of key exchange requests
The function is disabled.
● Authentication requests before key exchange
Maximum number of authentication requests of the CP with the master before the
session key is renewed.
If you enter 0 (zero), the function is deactivated and the session key is renewed only
depending on the key exchange interval.
Recommendation: Set the number for the CP twice as high as for the master.
● Key exchange interval
Period after which the session key is exchanged again between the CP and the master.
If you enter 0 (zero), the function is deactivated and the key will never be renewed.
The interval must be matched up on both communications partners.
● Authentication timeout
Maximum waiting (seconds) time for the response from the master to an authentication
request of the CP.
Exceeding the wait time is evaluated as an error by the CP. In this case, the CP
generates a Security event and sends this to the master.
Range of values: 1 ... 65535
● Pre-shared key
The pre-shared key of the CP must be identical to the pre-shared key that the master
uses.
The key must have the key length configured above (2 characters per byte).
The pre-shared key can be configured in two ways:
– Manual configuration
– Import as file
CP 1542SP-1, CP 1542SP-1 IRC, CP 1543SP-1
Operating Instructions, 01/2017, C79000-G8976-C426-03
Enter the pre-shared key manually as a hexadecimal value.
Import the pre-shared key from the file system of the engineering station if the pre-
shared key was generated by the master or another system.
4.5 Telecontrol communication (CP 1542SP-1 IRC)
Configuration and operation
85