connection

A connection is when two or more conductors are physically connected to each other. In communication technology, however, the term connection is also used for a logical or physical circuit with which two or more points of a communication link are connected.

1. Physical connection of conductors, wires or cores refers to a connection technique with which cores are firmly connected to other cores, with a contact or a contact pin. These connections are fixed and can only be released again with a certain amount of effort. A classic connection technique is the solder connection. Here, the cores are connected to each other with solder. In power electronics, soldered connections made of soft solder reach their limits in that the operating temperatures are very high and soft-soldered connections can no longer withstand these temperatures. Therefore, ultrasonic welded joints are used here.
   

   Connection techniques with fixed connection

   Other connection techniques used in acoustics, communications technology and computer technology are the cable lug with the screw connection, the insulation displacement connection, the solderless wrapped connection, in which the wire is wrapped around the contact pin, and crimping, a crimping technique.
2. In communication technology, a distinction is made between connections between two and more communication partners: there is the point-to-point connection, the point-to- multipoint connection and the multipoint connection. In addition, a distinction is made between fixed connections, virtual connections, selected virtual connections, logical connections, to name a few.
3. To enable data transmission between two or more communication partners, transmission channels, switching equipment and other functional units must be interconnected.
   

   Simple flow chart of a communication connection with data transmission

   A connection consists of several individual steps. On the one hand, there is the establishment of the connection, the data transfer via an established connection and the termination of the connection. In addition to the connection on the physical level, which can be fixed or virtual, a logical connection must also be established. A logical link( LL) appears to be firmly established and exclusive above a certain level, even though the messages, for example physical, are transmitted together with other messages by multiplexing.