Bosch Appliances LBC 325X installation manual Some notes on the RS-485 Network interface

Intellivox DDC Installation Manual Appendix EN 17

Fig 13 Optional high frequency decoupling for 70 V / 100 V systems.

Conclusion:

Because the Intellivox can be a part of a complex installation it is impossible to prescribe a fixed grounding strategy that will perform best in all situations. Safety, immunity and reduction of emission are very important issues that should always determine the ground configuration that is applied.

This appendix describes some methods to eliminate possible noise caused by ground loops without sacrificing safety or emission, although a minor degradation of the immunity can be expected which is depending on the configuration chosen.

3.3 Some notes on the RS-485

network interface.

In order to integrate the unit in a surveillance and control network a full duplex RS-485 terminal is incorporated. The RS-485 standard is chosen for the ability of driving long cables, the simplicity of the network topology and high immunity to external electromagnetic fields which results in low error rates. A disadvantage of the full duplex set up is the required 5 wire interface. The RS-485 interface on the unit exists of a differential input port (AB), a differential output port (YZ) and a dedicated network ground terminal (DGND).

Fig 14 Structure of the RS-485 network

Bosch Security Systems July 2003