Siemens SIMATIC NET PROFIBUS manual Cable Connections Cable Connections to Network Components

Passive Components for RS-485 Networks

4.8Cable Connections

4.8.1Cable Connections to Network Components

Sometimes, a connection between two different LAN cable sections is necessary, for example, a transition from the standard LAN cable to a section with trailing cable.

The easiest way to implement this transition is to use the two LAN cable attachments of a bus connector, bus terminal or repeater. The attachment of the cables is described in detail in this chapter. For information about laying cables and mechanical protection of the cables refer to Appendix C “Installing LAN Cables”.

For the transition from the underground cable to the standard LAN cable, it is advisable to protect against overvoltage (see Appendix B “Lightning and Overvoltage Protection”.

4.8.2Cable Connection without Bus Connection Elements

Sometimes, a connection is necessary between LAN cable sections at locations where no nodes or network component connections are intended, for example, when repairing a broken LAN cable. Note the following information:

The all-round shielding of the LAN cable must be retained

To make the cable connection, use, for example, a commercially available sub-D male connector and socket with metal casing. Only sub-D components with a spring shield collar ensure a reliable shield connection.

Avoid accidental shield contact with the environment.

The male connector shield should not make any undefined, accidental contact to conductive parts, since this can lead to undefined shield currents. Connect the connector casing either permanently to ground potential or wrap the connector in insulation that reliably prevents contact.

PROFIBUS Networks SIMATIC NET	4-63
6GK1970-5CA20-0AA1 Release 2 05/2000