TSAP

 Home  Back  Next

TSAP = Transport Service Access Point

 

On the transport layer, OSI (H1) uses so-called TSAPs to address applications. These connection endpoints are required both for OSI (H1) and RFC 1006 connections.

 

Parameters for ISO (H1) connections

Parameters for RFC 1006 connections

Station A

Station B

Station A

Station B

Own TSAP A

Dest TSAP B

MAC Address A

Own TSAP B

Dest TSAP A

MAC Address B

Own TSAP A

Dest TSAP B

IP Address A

Own TSAP B

Dest TSAP A

IP Address B

 

In order to establish the connection, the value in the Own TSAP field of communication partner A must match the value in the Dest TSAP field of communication partner B, i.e. they must match crosswise. Accordingly, the Dest TSAP field of station A must match the Own TSAP field of station B.

 

Own TSAP (station A) = Dest TSAP (station B)

Dest TSAP (station A) = Own TSAP (station B)

 

This condition can easily be met if you set the same value for the Own TSAP and Dest TSAP fields. These values may be identical.

If multiple connections are to be established between 2 stations, the TSAPs for the individual connections be must different.

To exactly specify a connection, the combination of TSAP + MAC address (or IP address) must be unique.

 

Rules for entering TSAPs for S7 connections

•TSAPs have a minimum length of 2 bytes and a maximum length of 8 bytes
•TSAPs can be entered as hex or ASCII characters.
•The TSAPs for S7 connections have a special meaning. See TSAP for S7 Connection and Routing TSAPs

Rules for entering TSAPs for S5 connections

•TSAPs have a minimum length of 2 bytes and a maximum length of 8 bytes for TCP/IP, and 16 bytes for H1.
•TSAPs can be entered as hex or ASCII characters.
•The TSAPs for S5 connections do not have a special meaning. They are selected arbitrarily.