Siemens Simatic S7-300 CPU 31xC and CPU 31x S7-300 - Manual (Page 36)

Communication
3.2 Communication services
CPU 31xC and CPU 31x, Technical data
3-8
Manual, Edition 08/2004, A5E00105475-05
Reference
• Details on SFCs are found in the Instruction list, for more details refer to the
STEP 7 Online Help or to the System and Standard Functions Reference Manual.
• For further information on communication, refer to the Communication with SIMATIC
manual.
3.2.5 S7 communication
Properties
A CPU can always operate in server or client mode in S7 communication: We distinguish
between
•
communication with unilateral configuration (for PUT/GET only)
• communication with bilateral configuration (for USEND, URCV, BSEND, BRCV, PUT,
GET)
However, the functionality depends on the CPU. A CP is therefore required in certain
situations.
Table 3-3 Client and server in S7 communication, using connections with unilateral / bilateral
configuration
CPU Use in server mode for
connections with unilateral
configuration
Use in server mode for
connections with bilateral
configuration
Use as client
31xC >= V1.0.0 Always possible at the
MPI/DP interface, without
programming the user
interface
Only possible with CP
and loadable FBs.
Only possible with CP
and loadable FBs.
31x >= V2.0.0 Always possible at the
MPI/DP interface, without
programming the user
interface
Only possible with CP
and loadable FBs.
Only possible with CP
and loadable FBs.
31x >= V2.2.0 Always possible at the
MPI/DP interface, without
programming the user
interface
• Possible at PN
interface with
loadable FBs, or
• with CP and loadable
FBs.
• Possible at PN
interface with
loadable FBs, or
• with CP and
loadable FBs.
The user interface is implemented using standard function modules (FBs) from the standard
library of STEP 7, under communication blocks.
Reference
For further information on communication, refer to the Communication with SIMATIC
manual.