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Further notes on operation
8.5 Setting the CPU time of day by the CP
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 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
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.
60
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.
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.
CP 343-1 ERPC
Manual, 03/2010, C79000-G8976-C239-02
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