Communication
4.2 Communication services
S7-400 Automation System, CPU Specifications
4-8 Manual, 10/2006, 6ES7498-8AA04-8BA0
4.2.4 S7 basic communication
Properties
S7-based communication is used to exchange data between S7 CPUs and the
communication-capable SIMATIC modules within an S7 station (acknowledged data
communication). The service is available via MPI subnet, or within the station to function
modules (FM).
You do not need to configure connections for basic S7 communication. The integrated
communication functions are called via SFCs in the user program.
SFCs for the Basic S7 Communication
The following SFCs are integrated in the operating system of the S7-400 CPUs:
Table 4-2 SFCs for the Basic S7 Communication
Block Block name Brief description
SFCs for external communication
SFC 65
SFC 66
X_SEND
X_RCV
Secure transmission of a data block to the communication partner.
SFC 67 X_GET Reading variables from a communication partner
SFC 68 X_PUT Writing variables to a communication partner
SFC 69 X_ABORT Cancellation of an established connection with transmission of data
SFCs for internal communication
SFC 72 I_GET Reading variables from a communication partner
SFC 73 I_PUT Writing variables to a communication partner
SFC 74 I_ABORT Cancellation of an established connection with transmission of data
Reference
● Refer to the
operation list
to learn which SFCs are included in the operating system of a
CPU.
● You can find detailed descriptions of the SFCs in the
STEP 7 Online Help
or
System and
Standard Functions
reference manual.
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