Siemens S7-300 Configuration Manual page 102

Configuring communications connections
5.5 Configuring ISO-on-TCP connection properties
The address parameters are configured with NCM S7 and saved in the CP database.
Modifications and extensions to the Industrial Ethernet network topology do not therefore
have any effect on the CPU user program.
Note
When you configure the Ethernet CP and the Ethernet destination station, the TSAPs of an
ISO-on-TCP connection must cross match:
Remote TSAP (in Ethernet CP) = local TSAP (in destination station);
Local TSAP (in Ethernet CP) = remote TSAP (in destination station);
Configuring addresses
STEP 7 displays proposed values for the relevant local and remote address information. If
necessary, you can set the TSAPs individually.
TSAP format
ISO-on-TCP connections have a TSAP length of 1 to 16 bytes. When you are entering
values, the current length is displayed automatically (visible display: 16 ASCII characters).
Local and remote TSAPs can be entered as hexadecimal values or as an ASCII string.
● If you enter the TSAP as an ASCII string, the characters are also displayed in
hexadecimal format.
● If you make your entries in hexadecimal, printable characters are displayed as an ASCII
value (8 hexadecimal characters are visible). If you enter non-printable characters, the
ASCII display changes to gray (ASCII input no longer possible) and the non-printable
characters are displayed as a period.
Note
Use at least 3 bytes to ensure unique addressing.
Local and remote TSAPs
Remote and local TSAPs can be identical since the connection is uniquely identified by the
different IP addresses. If more than one connection is required between two stations, the
TSAPs must also be different.
Default TSAPs
When configuring the local and remote TSAPs, there is a default value "TCP-1" for the first
connection between the two partners (can be changed). For a new connection between the
two partners, the default value "TCP-2" is proposed. With a new connection to a new
partner, the value TCP-1 is used again.
102
Configuring and commissioning S7 CPs for Industrial Ethernet
Configuration Manual, 09/2013, C79000-G8976-C182-13