Brainboxes PX-101 Product Manual page 31

Optional Grounding Arrangements
Proper operation of the cable circuit, according to TIA EIA: 485 A (1995) requires that the cable ground
shield is not connected directly to the equipment ground shield. A current limiting resistor should be used in
series with the shield to avoid possible large current flow due to differences in ground potential. Any one of
the methods shown below can do this.
The circuit common of the equipment is connected to protective ground, at one point only by a 100 , ±20%
resistor with a power dissipation rating of 1/2W. An additional provision may be made for the resistor to be
bypassed with a strap to connect signal common and protective ground directly together when specific
installation conditions necessitate.
Configuration A
Configuration B
PX Range Product Manual Version 2.3 © Copyright Brainboxes Limited 2013 Page 31 of 45