Siemens Simatic S7-200 System Manual page 173

Configuration
The only setting you must make on the CPU 215 to use it as a DP slave is the station
address of the DP port of the CPU. This address must match the address in the configuration
of the master. You can use STEP 7-Micro/WIN to modify the CPU configuration for the DP
port address and then download the new configuration to the CPU 215.
The address of the CPU 215 DP port can also be set with a DP configuration device
attached to the DP port. Setting the DP port address with one of these devices is only
possible if the DP port address shown in the STEP 7-Micro/WIN CPU configuration is the
default address of 126. The DP port address set by STEP 7-Micro/WIN overrides an address
that is set by means of a DP configuration device.
Note
To restore the default DP port address once the port address has been changed with a DP
configuration device, you must perform the following steps:
The master device exchanges data with each of its slaves by sending information from its
output area to the slave's output buffer (called a "Receive mailbox"). The slave responds to
the message from the master by returning an input buffer (called a "Send mailbox") which the
master stores in an input area. See Figure 9-10.
The CPU 215 can be configured by the DP master to accept output data from the master and
return input data to the master. The output and input data buffers reside in the variable
memory (V memory) of the CPU 215. When you configure the DP master, you define the
byte location in V memory where the output data buffer should start as part of the parameter
assignment information for the CPU 215. You also define the I/O configuration as the amount
of output data to be written to the CPU 215 and amount of input data to be returned from the
CPU 215. The CPU 215 determines the size of the input and output buffers from the I/O
configuration. The DP master writes the parameter assignment and I/O configuration
information to the CPU 215.
S7-200 Programmable Controller System Manual
C79000-G7076-C230-02
Network Communications and the S7-200 CPU
1. Using STEP 7-Micro/WIN, modify the DP port address in the CPU
configuration to an unused value (not 126).
2. Download the CPU configuration to the CPU 215.
3. Again using STEP 7-Micro/WIN, modify the DP port address in the CPU
configuration to the default address (126).
4. Download the CPU configuration to the CPU 215.
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