Siemens SIMATIC NET CP 243-1 IT Technical Manual page 21

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S7 communication
The XPUT and XGET S7 services are used to communicate data between two
controllers. The CP 243-1 IT can be used both as client and as server.
Communication between a CP 243-1 IT and an OPC server running on a PC/PG
uses the READ and WRITE S7 services. The CP 243-1 IT is always the server
here. Other S7 services (e.g., the service for automatic scanning of objects on an
S7-200 - DBs, and so on) are not supported.
The following data types or data areas are supported by the CP 243-1 IT.
CP 243-1 IT as client
Read and write accesses
• Data type is always BYTE.
• Only variables can be accessed on the local system.
• Accessible memory areas on the partner system are inputs, outputs, markers
and variables with an S7-200 as partner.
• Accessible memory areas on the partner system are inputs, outputs, markers
and data areas with an S7-300 or an S7-400 as partner.
CP 243-1 IT a server
Write accesses
• Data type is BOOL, BYTE, WORD or DWORD.
• Use of data types CHAR, INT, DINT and REAL depends on the firmware status
of the S7-200 CPU being used.
• Accessible memory areas on the local system are inputs, outputs, variables,
markers and status bits.
Read accesses
• Data type is BOOL, BYTE, WORD or DWORD.
• Use of data types CHAR, INT, DINT and REAL depends on the firmware status
of the S7-200 CPU being used.
• Accessible memory areas on the local system are inputs, outputs, variables,
markers, system area and status bits.
Note
When an S7-300 or S7-400 is the server on a client running on an S7-200 system,
the CP 243-1 IT expects this server to always behave passively. This means that,
in such cases, the S7-300 or S7-400 system is not allowed to send S7 jobs to the
S7-200 system.
Communication with STEP 7 Micro/WIN 32
With communication between a CP 243-1 IT and STEP 7 Micro/WIN 32, the CP
243-1 IT is always the server. STEP 7 Micro/WIN 32 is always the client here.
CP 243-1 IT
J31069-D0429-U001-A0-7618
Features and Functions
21