Fire-Lite LCD-80F Remote LCD Annunciator - Manual (Page 26)

EIA-485 Shield Termination EIA-485 Connections
26
Document 51338 Rev. B 08/24/05 P/N 51338:B
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 elec-
trical 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 LCD-80F 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.