Technical data

Table Of Contents
Open Communication via Industrial Ethernet
System Software for S7-300/400 System and Standard Functions - Volume 2/2
23-2
A5E00739858-01
23.2 Function of FBs for Open Communication via
Industrial Ethernet
Connection-oriented and Connectionless Protocols
The following types of protocols are distinguished in the data communication:
Connection-oriented protocols:
These establish a logical connection to the communication partner before data
transmission is started. After the data transmission is complete, they then
terminate the connection, if necessary. Connection-oriented protocols are used
for data transmission when reliable, guaranteed delivery is of particular
importance. In general, many logical connections can exist on one physical line.
The following connection-oriented protocols are supported with FBs for open
communication via Industrial Ethernet:
- TCP/IP native as per RFC 793 (with connection types B#16#01 and
B#16#11)
- ISO on TCP as per RFC 1006 (with connection type B#16#12)
Connectionless protocols:
These work without a connection. There is thus no establishment and
termination of a connection with a remote partner. Connectionless protocols
transmit data unacknowledged, with no reliable, guaranteed delivery to the
remote partner.
The following connection-oriented protocols are supported with FBs for open
communication via Industrial Ethernet: UDP as per RFC 768 (with connection
type B#16#13)
How the function blocks actually function depends on the protocol variant being
used. This is discussed in detail in the following section.