Siemens SIMATIC S7-400H System Manual page 216

Communication
14.1 Communication services
S7 communication services provide the following options:
● During system configuration, you configure the connections used by the
● You can establish several connections to the same partner. The number of
● You can configure fault-tolerant S7 connections using the integrated PROFINET
S7 communication allows you to transfer a block of up to 64 KB per call to the SFB. An
S7-400 transfers a maximum of 4 tags per block call.
SFBs for S7 Communication
The following SFBs are integrated in the operating system of the S7-400 CPUs:
Table 14- 3 SFBs for S7 Communication
Block Block name
SFB 8 USEND
SFB 9 URCV
SFB 12 BSEND
SFB 13 BRCV
SFB 14 GET
SFB 15 PUT
SFB 16 PRINT
SFB 19 START
SFB 20 STOP
SFB 21 RESUME
SFB 22 STATUS
SFB 23 USTATUS
Integration into STEP 7
S7 communication offers communication functions through configured S7 connections. You
use STEP 7 to configure the connections.
S7 connections with an S7-400 are established when the connection data is downloaded.
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S7 communication. These connections remain configured until you download a new
configuration.
communication partners accessible at any time is restricted to the number of connection
resources available.
interface.
NOTICE
Downloading the connection configuration in RUN
When you load a modified connection configuration during operation, connections which
have been set up which are not affected by changes in the connection configuration
may also be aborted.
Brief description
Send data to a remote partner SFB with the type "URCV"
Receive asynchronous data from a remote partner SFB with the type "USEND"
Send data to a remote partner SFB with the type "BRCV"
Receive asynchronous data from a remote partner SFB with the type "BSEND"
With this data transfer, a larger amount of data can be transported between the communication
partners than is possible with all other communications SFBs for the configured S7
connections.
Read data from a remote CPU
Write data to a remote CPU
Send data via a CP 441 to a printer
Carry out a reboot (warm restart) or cold restart in a remote station
Set a remote station to STOP state
Carry out a hot restart in a remote station
Query the device status of a remote partner
Uncoordinated receiving of a remote device status
System Manual, 03/2012, A5E00267695-11
S7-400H