Hardware manual

RS422/485 Information PCI VELOCITY / OPTO ISO RS422/485
Chapter 4 Page 48
current flow due to differences in ground potential. Any one of the
methods shown in Figure 4-7, below can do this.
Figure 4-7 - Optional Grounding Arrangements For A
PCI RS422/485 Card.
Configuration A)
Configuration B)
Configuration A) The circuit common of the equipment is
connected to protective ground, at one point only by a 100
Ω, ±20% resistor with a power dissipation rating of 1/2W. An
additional provision may be made for the resistor to be bypassed
GWG
SG
GWG
100
Ω
(
1/2
)
W
SG
SG = Signal Ground Interchange circuit.
GWG = Green wire ground of power system.
= Protective ground of frame ground.
= Circuit ground or circuit