Further notes on operation   
8.5 Setting the CPU time of day by the CP 
  CP 343-1 ERPC 
60  Manual, 03/2010, C79000-G8976-C239-02 
8.4.2  Detection of double IP addressing in the network 
Response of the CP to double addressing in the network 
To save you timeconsuming troubleshooting in the network, the CP detects double 
addressing in the network. 
The reaction of the CP when double addressing is detected varies as follows: 
●  CP during startup 
When the CP starts up (after power down or after the initial addressing), the CP queries 
its own IP address on the network. If a response is sent in reply, the CP does not start up! 
The error is indicated by an LED (“STOP with internal error" is displayed) and an entry is 
made in the internal diagnostic buffer. 
The CP remains in STOP mode. 
When you eliminate the cause by removing the device with the same IP address or changing 
its address, you must then restart the CP. 
●  CP in RUN mode 
In RUN, the CP also sends this query at intervals of one minute to detect double IP 
addresses. 
If a double IP address is detected, the CP also reports this via the LEDs (BUSF LED) and 
generates an entry in the diagnostic buffer. 
The CP remains in RUN mode. 
8.4.3  Obtain IP address vie DHCP: CP STOP on expiry of the lease 
Response of the CP to expiry of the lease 
If you have configured “Obtain IP address from a DHCP server", when the CP starts up, it is 
assigned a valid IP address by the DHCP server for a restricted time (period of the lease). 
 
NOTICE 
 
When the lease expires the reaction of the CP is as follows: 
The CP changes to STOP and loses the previously assigned IP address if the DHCP server 
does not extend it before expiry of the lease. All communication connections are 
terminated. 
 
8.5  Setting the CPU time of day by the CP 
Update interval 
The CP updates the time of day of the CPU at intervals of 1 minute.