Ground and Shield Considerations
MS-5000 Multidrop Concentrator User’s Manual
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Appendix D — 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 7). Pin 7 is normally con-
nected to pin 1 (chassis ground) in the concentrator; 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 concentrator by Microscan technicians.
Any data line, as necessary, can be shielded. If used, shielding should be
isolated from the concentrator and grounded only to the host earth ground.
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 A-4.
1. Examine the shielding connection at or near the concentrator cable
connector.
2. Cut the shielding connection as required.
Ground Loops
Ground loops
, signal degradation due to different ground potentials in com-
municating devices, can be eliminated or minimized by ensuring that the
host, concentrator(s), scanner(s), decoder(s), and their power supplies
are
connected to a common earth ground.
In some cases it may be possible to fully isolate devices by insulating
mounting under each device and using the optional ground wire in the LAN
cable rather than the power supply cable to ground the device chassis.
(Power supplies that provide earth ground to the chassis should not be
used here without modifications.)
Ground loops can be avoided as shown in figure A-4. In this method, the
optional ground wire (see Figure A-4 “Network Grounding Diagram” on
page A-8) is disconnected at each device, and each device chassis is earth-
grounded through the power supply. The power supply must provide a reli-
able earth ground connection.
Summary of Contents for MS-5000
Page 1: ...MS 5000 Multidrop Concentrator User s Manual P N 83 005000 REV J...
Page 8: ...viii MS 5000 Multidrop Concentrator User s Manual...
Page 52: ...Chapter 3 Menu Configuration 3 18 MS 5000 Multidrop Concentrator User s Manual 3 Serial Config...
Page 66: ...Chapter 4 Serial Commands 4 14 MS 5000 Multidrop Concentrator User s Manual 4 Operations...
Page 90: ...A 14 MS 5000 Multidrop Concentrator User s Manual Appendices...
