Installation

VLC Input/Output Voltage Levels
Button VLC Output Button VLC Output
House 1/2 supply + 3.69 V 5 1/2 supply – 0.41 V
Door 1/2 supply + 2.87 V 4 1/2 supply – 1.23 V
8 1/2 supply + 2.05 V 3 1/2 supply – 2.05 V
7 1/2 supply + 1.23 V 2 1/2 supply – 2.87 V
6 1/2 supply + 0.41 V 1 1/2 supply – 3.69 V
NOTE:The 1/2 supply voltage will vary from system to system because of slight variations in
transformer voltages.
The 1/2 supply voltage will also vary from station to station within a system due to the varying
cable voltage losses associated with the varying lengths of cable, to different stations.
SHLD (at Master Station)
��Linked to NEG terminal by a track on the Termination PCB.
��For connection of outer shields where shielded cables are used for TC and VLC.
��Provides protection against electrical interference for the inner core wires by shunting
interference to 0 Volts.
SHLD (at all other stations)
��Floating terminal (not connected to anything).
��For connection of outer shield where shielded cables are used for TC and VLC.
��Provides continuity of outer shield, from cable to cable, on loop wired systems.
��Provides terminating point for outer shield on star wired systems.
COM1 and COM2
��Balanced audio pair for communication, chime and security voice on 8-wire systems (also
caters for Music and Monitoring on 6-wire systems).
��Normal dc voltage level for each terminal is approx 1/2 supply with respect to NEG.
��DC voltage for COM1 should be the identical to the DC voltage for COM2 (within 0.02V).
��AC signal (audio signal) on COM1 is equal but opposite in phase to the AC signal on COM2,
providing a differential audio signal.
��The balanced audio design employed provides good immunity to interference by rejecting
common mode signals (noise) and amplifying differential signals (audio).
MUS1 and MUS2
��Balanced audio pair for Music and Monitoring on eight-wire systems.
��Normal dc voltage level for each terminal is approximately 1/2 supply with respect to NEG.
��DC voltage for MUS1 should be the identical to the DC voltage for MUS2 (within 0.02V).
��AC signal (audio signal) on MUS1 is equal but opposite in phase to the AC signal on MUS2,
providing a differential audio signal.
��The balanced audio design employed provides good immunity to interference by rejecting
common mode signals (noise) and amplifying differential signals (audio).
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