Siemens Simatic S7-300 CPU 31xC and CPU 31x S7-300 - Manual (Page 35)

Communication
3.2 Communication services
CPU 31xC and CPU 31x, Technical data
Manual, Edition 08/2004, A5E00105475-05
3-7
See also
Distribution and availability of S7 connection resources (Page 3-29)
Connection resources for routing (Page 3-31)
3.2.2 PG communication
Properties
PG communication is used to exchange data between engineering stations (PG, PC, for
example) and SIMATIC modules which are capable of communication. This service is
available for MPI, PROFIBUS and Industrial Ethernet subnets. Transition between subnets is
also supported.
PG communication provides the functions needed to download / upload programs and
configuration data, to run tests and to evaluate diagnostic information. These functions are
integrated in the operating system of
SIMATIC S7 modules.
A CPU can maintain several simultaneous online connections to one or multiple PGs.
3.2.3 OP communication
Properties
OP communication is used to exchange data between operator stations (OP, TP, for
example) and SIMATIC modules which are capable of communication. This service is
available for MPI, PROFIBUS and Industrial Ethernet subnets.
OP communication provides functions you require for monitoring and modifying. These
functions are integrated in the operating system of SIMATIC S7 modules. A CPU can
maintain several simultaneous connections to one or several OPs.
3.2.4 Data exchanged by means of 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
exchange). Data are exchanged across non-configured S7 connections. The service is
available via MPI subnet, or within the station to function modules (FM).
S7-based communication provides the functions you require for data exchange. These
functions are integrated into the CPU operating system. The user can utilize this service by
means of "System function" (SFC) user interface.