Configuration
3.6 Reaction of the CP 243-1 to configuration errors
CP 243-1
Operating Instructions, 03/2012, C79000-G8976-C244-02
91
If you want to make use of the free connections on your S7-300 or S7-400 system, the client
end must still be configured for each of these connections. In STEP 7 Micro/WIN 32, there is
no difference in the use of such connections and communication via connections that were
configured on the S7-300 or S7-400 system. Here, you simply need to remember that, with
free connections, the first byte of the TSAP via which such connections operate on S7-300
and S7-400 systems must always have the value 0x03. The second byte of the TSAP is
derived in a way similar to the procedure described above from the rack and the slot number
of the CPU used in your S7-300 or S7-400 system. This means that, with a free connection,
the communication access point on the S7-300 or S7-400 system is always located on the
CPU and not on the Ethernet communications processor.
Note
S7-200 systems do not support free connections. This means that, with an S7-200 system,
you will always have to configure each connection regardless of whether your system is
being used as a client or a server.
3.6 Reaction of the CP 243-1 to configuration errors
When the CP 243-1 detects an invalid configuration, it tries to obtain its TCP/IP address
parameters (IP address, subnet mask and IP address of the gateway) via a BOOTP/DHCP
service. The CP 243-1 continues to attempt this for approximately 1 minute. When it fails to
receive a reply from a BOOTP/DHCP service within this time or the reply is invalid or
contains errors, the red LED ("SF") flashes for approximately 30 seconds. This procedure
continues cyclically until the CP 243-1 either finds a valid configuration in the memory of the
S7-200 CPU or receives a valid reply from a BOOTP/DHCP server.
When the CP 243-1 receives a valid BOOTP response, it configures itself as explained
below:
● IP address, subnet mask and IP address of the gateway are taken from the
BOOTP/DHCP response
● The transmission type is set to "Autonegotiation" (automatic setting).
● The monitoring time for connections (keepalive) is set to 30 seconds
With this configuration, the CP 243-1 is then able to access the S7-200 CPU via Ethernet
with STEP 7 Micro/WIN 32. A new valid configuration can now be obtained in this way.
Communication with other controllers is not possible in this status. After a reset, the CP 243-
1 then adopts the settings of the new configuration.
Note
Autonegotiation (automatic setting) mode will only work when all connected network
components support this mode.
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