S7 communication via Industrial Ethernet
S7 communication via Industrial Ethernet permits program-controlled communication using
communication SFBs/FBs and configured S7 connections. The CP 243-1 supports S7
communication via Industrial Ethernet with the XPUT/XGET and READ/WRITE services. Up
to 212 bytes of user data can generally be transmitted per request. If the CP 243-1 is
operating as a server, up to 212/222 bytes of user data can be transferred in read requests
(see Technical specifications (Page 119)).
The CP 243-1 supports a maximum of 8 S7 communications channels to clients or servers
on one or more remote communications partner. The CP 243-1 works according to the
client/server principle on each channel. Per channel only one request at a time is accepted,
processed and answered with a positive or negative response. The CP 243-1 only accepts a
new request after a response has been sent.
If the CP 243-1 receives several requests on a channel configured as a server, only the first
request is processed. The subsequent requests are ignored until completion of the
transaction, in other words, until a response is sent. The CP 243-1 has no channel-specific
request administration and does not buffer requests.
Requirements for communication with a PC/PG
Just as previously, a PG/PC can access the S7-200 CPU via the PPI interface. This access
is also possible via Ethernet using a CP 243-1. The following requirements must first be met:
● An Ethernet card is installed and configured on the PG/PC and an Ethernet and TCP/IP
● STEP 7 Micro/WIN 32, version 3.2.3 or higher, is installed on the PG/PC.
● The CP 243-1 has a valid IP address. This address may be permanently specified in the
At any one time, only one STEP 7 Micro/WIN 32 can communicate via a CP 243-1 with the
S7-200 CPU. The Ethernet interface must be used when configuring the IT services.
Types of communication
The CP 243-1 has three types of S7 communication relationships that can be used
individually or as a combination.
1. Link to STEP 7-Micro/WIN 32
2. Link to other remote components of the SIMATIC S7 family
3. Link to OPC-based applications on a PC/PG
Operating Instructions, 03/2012, C79000-G8976-C244-02
connection to the CP 243-1 exists (where necessary via routers, firewalls, etc.)
configuration or obtained from a BOOTP/DHCP server.
Application and properties
1.5 S7 communication via Industrial Ethernet