Ground And Shield Considerations; Figure 1-12 Grounding Diagram, Scanner-Host - Microscan MS-615 User Manual

Chapter 1 Setup and Installation

Ground and Shield Considerations

Proper grounding is necessary for operator safety, noise reduction, and the
protection of equipment from voltage transients. Buildings, including any
steelwork, all circuits, and all junction boxes must be grounded directly to an
earth ground in compliance with local and national electrical codes.
RS-232 signals have a common signal ground (pin 4). Pin 4 is normally con-
nected to pin 13 (chassis ground) in the scanner; however, under certain
conditions (e.g., when potential differences exist between power outlet
grounds) signal and chassis grounds can be isolated from each other inside
the scanner by Microscan technicians.
Noise Interference
Noise interference
can be minimized if
cabling subject to
noise interference is
twisted and/or
shielded or encased
in grounded conduit,
and the conduit or
shielding ("drain"
line) is grounded
only to earth ground
at the host, as
shown in figure
1-12. You might
need to examine
and if necessary cut the shielding connection at or near the scanner cable con-
nector.
Ground Loops
Ground loops, signal degradation due to different ground potentials in com-
municating devices, can be eliminated or minimized by ensuring that both
the host, scanner, and their power supplies are connected to a common
earth ground.
1-16
MS-610 Scanner User's Manual
HOST
Shielding
Communications Cable
Earth Ground
SCANNER

Figure 1-12 Grounding Diagram, Scanner-Host