ADT Security Services ADT-LCD40 Manuel D’Utilisation
EIA-485 Shield Termination
EIA-485 Shield Not in Conduit
25
Document 50520 Rev D 7/25/00 P/N 50520:D
Section 5:
EIA-485 Shield Termination
The EIA-485 circuit must be wired using a twisted, shielded pair cable
with a characteristic impedance of 120 ohms (+/- 20%). Do not run
cable adjacent to or in the same conduit as 120 VAC service, noisy
electrical circuits that are powering mechanical bells or horns, audio
circuits above 25 V
with a characteristic impedance of 120 ohms (+/- 20%). Do not run
cable adjacent to or in the same conduit as 120 VAC service, noisy
electrical circuits that are powering mechanical bells or horns, audio
circuits above 25 V
RMS
, motor control circuits or SCR power circuits.
Note: To ensure static (ESD - electrostatic discharge) protection, all
enclosures, including the ADT-LCD40 Series electrical box, must be
connected to earth ground! Never use the EIA-485 shield for this
purpose. The EIA-485 shield is for radiated noise emission protection
(RFI, EMI). Refer to the following figures for details on EIA-485 shield
termination.
enclosures, including the ADT-LCD40 Series electrical box, must be
connected to earth ground! Never use the EIA-485 shield for this
purpose. The EIA-485 shield is for radiated noise emission protection
(RFI, EMI). Refer to the following figures for details on EIA-485 shield
termination.
5.1
EIA-485 Shield Not in Conduit
The EIA-485 line allows the FACP to communicate with the
ADT-LCD40 Series Annunciators. The shield for the EIA-485 line
must be connected to earth ground at the FACP but must be left floating
(no connection) at the annunciator if it is the first or only device on the
EIA-485 line. If a second annunciator is connected, the shield leaving
the first annunciator must be left floating. The shield entering the sec-
ond annunciator must be connected to the three-gang box or Earth
Ground terminal (P2-7) on the second annunciator. If additional annun-
ciators are connected, the shield leaving each enclosure must be left
floating and the shield entering each must be connected to the three-
gang box or the Earth Ground terminal (P2-7) on the annunciator.
ADT-LCD40 Series Annunciators. The shield for the EIA-485 line
must be connected to earth ground at the FACP but must be left floating
(no connection) at the annunciator if it is the first or only device on the
EIA-485 line. If a second annunciator is connected, the shield leaving
the first annunciator must be left floating. The shield entering the sec-
ond annunciator must be connected to the three-gang box or Earth
Ground terminal (P2-7) on the second annunciator. If additional annun-
ciators are connected, the shield leaving each enclosure must be left
floating and the shield entering each must be connected to the three-
gang box or the Earth Ground terminal (P2-7) on the annunciator.