GE IC754CSF15CTD, Руководство пользователя по оборудованию

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GFK-2402D Chapter 4 Detailed Operation 4-13
4
Grounding A signal return path between transmitting and receiving devices must be
provided. This return path is separate from the Rx and Tx data lines and the
other 422/485 signals supported by the QuickPanel View/QuickPanel Control,
and may be provided by a separate conductor in the cable. Connect both
ends of the signal return conductor to Signal Ground (pin #7). Shielding or use
of a twisted pair for this connection is not necessary.
For installations where all devices are in the same cabinet and have the same
ground potential between devices, connecting Signal Ground between all the
devices on the 422/485 network is adequate to ensure proper voltage levels
at the devices.
However, if there is a difference in ground potential between devices, such as
when the devices are in widely separated cabinets, signal grounds on a
422/485 network should not be tied together. The cable shield and signal
ground should be connected together at only one device, closest to the earth
ground connection.
The signal and frame grounds of the QuickPanel View/QuickPanel Control are
capacitively coupled, but in some devices these ground references are
connected together. Connect Signal Ground (pin #7) to Frame Ground (pin
#1) and then to earth ground on the QuickPanel View/QuickPanel Control only
in the circumstance where the other devices separate their signal and frame
grounds and the QuickPanel View/QuickPanel Control is the only device with
frame and signal ground connected to earth ground.
Shielding Shielded cable is required for compliance with CE Mark and FCC
requirements. The cable shield should be connected to the metal connector
shell or by pin 1 of the QuickPanel 25-pin serial connector. Shield and signal
ground (pin 7 of the 25pin connector or pin 5 of the 9-pin serial connector)
should not be connected directly together.
Caution
Do not connect Signal Ground (pin #7) to Frame Ground (pin #1) on
the QuickPanel View/QuickPanel Control, except in the specific and
limited circumstances noted in the Grounding section above.