Omega Vehicle Security OMP-MODL - Manual (Page 50)

3... I NTERFACE M ODULES
U SING T HE OMP-MODL 3-26
To minimize noise pickup on sensor wiring between the OMP-MODL and the
end sensor or signal source, 18 to 22 AWG shielded, twisted pair wire is
recommended.
FYI: Shielded wire minimizes the amount of noise picked
up by the internal conductors carrying the signals by
providing an `electrical shell’ or Faraday cage around the
internal conductors.
Twisted pair wiring exposes both conductors equally to
the ambient electrical noise. This common-mode type
noise is easier to reject by the Interface Modules input
signal conditioning circuitry than un-balanced (or
differential) noise.
Shielding and/or twisted pair wire is especially recommended in electrically
noisy environments for optimum signal protection. If shielded wire is used, a
ground wire should be run from the MLAD-1 module Chassis Ground
(terminal strip connection #16) to an earth ground connection to conduct
away noise picked up by the thermocouple shield (Figure 2-8). Only one
ground wire is required as all of the Shield terminal strip connections are
interconnected within the logger and routed to the MLAD-1 Chassis Ground
terminal.
NOTE: Do not ground the signal wiring shield conductor at the sensor end
(the end away from the OMP-MODL) as this can induce additional noise into
the sensor wiring..
1 2 3 4 5 6 7 8 9 10 11 12
Terminal Strip
Shield
ml141
+
-
Shielded Twisted
Pair Line
Figure 3... -15: VDC signal (and optional shield) terminal strip connection
VDC-High
Range Icon