Configuring Hardware and Communication Connections STEP 7.pdf

Configuring Connections
12.7 Blocks for Different Connection Types
Blocks for Use with S7 Connections
The system function blocks are integrated in the CPUs of the S7-400.
For S7-300, with newer CPUs and CPs, you can operate S7 communication
actively (that is, as client) by means of the interface of the CP. The blocks (FBs)
have the same number and designation as the SFBs of the S7-400; however, they
must be called up cyclically in the user program of the S7-300-CPU. You can find
the blocks in the SIMATIC_NET_CP library.
The CP must support the client function for S7 communication.
The CPU 317-2 PN/DP with PROFINET interface can also be configured as a
client for S7 communication. In this case, the same blocks are used as in the case
for the S7-300 with CP mentioned above. These blocks are also in the Standard
Library (Communication Blocks/CPU_300). The client function is only available with
the PROFINET interface.
SFB/FB/FC Designation Brief Description
SFB8/FB8 USEND Uncoordinated data exchange using a send and a receive SFB
SFB9/FB9 URCV
Max. length SFB 8/9: 440 bytes, split into 4x100 bytes.
Max. length FB 8/9: 160 bytes
SFB12/FB12 BSEND Exchange blocks of data of variable length between a send SFB and
SFB13/FB13 BRCV
a receive SFB
Max. length SFB 12/13: 64 KB
Max. length FB 12/13: 32 KB
SFB14/FB14 GET Read data from a remote device
Max. length SFB 14: 400 bytes, split into 4x100 bytes
Max. length FB 14: 160
SFB15/FB15 PUT Write data to a remote device
Max. length SFB 15: 400 bytes, split into 4x100 bytes
Max. length FB 15: 160
SFB19 START Execute a restart (warm restart) on a remote device
SFB20 STOP Switch a remote device to STOP mode
SFB21 RESUME Execute a hot restart in a remote device
SFB22 STATUS Specific query of the status of a remote device
SFB23 USTATUS Receive status messages from remote devices
SFC62 CONTROL Query the status of the connection that belongs to an SFB instance
FC62 C_CNTRL Query the status of a connection (for S7- 300 CPUs)
Configuring Hardware and Communication Connections with STEP 7
12-18 A5E00706939-01