Unitec C-Start Installation Manual - Manual (Page 16)

C - S T A R T
Document Number: CST1001 12
Document Name: C-Start Installation Manual
intercom wiring is sharing conduit with other communications wiring, but not required.
Unitec does not supply intercom systems.
3.5.2 Intercom Connections
The Intercom has two connectors which control the way in which the intercom is
wired and the mode of operation. J17 is the interface and connects to the customer’s
intercom unit. J23 is used to select mode of operation (two, three, or four wire
intercom systems). Twisted pair / fully shielded cable is recommended for optimum
performance.
3.5.3 Intercom Adjustments
The Intercom system has the ability to sense when voice band audio signals are
present. This allows the speakers in the unit to revert to a passive intercom mode.
This bypasses the internal audio section and allows the left speaker to be used as
an intercom.
3.5.4 Connection Overview
Call Function: The unit will initiate a call function by closing the contacts on RL5. By
default, J17-Pin 1 (H1) and J17-Pin 2 (H2) will always reflect the contact closure of
RL5. This is the default for the four-wire mode when both the call function and audio
are completely separated. More detailed instructions on this follow.
Audio: When the C-Start intercom mode is active, the audio section is floating and is
not relative to ground. By default, J17-Pin 3 (SP+) and J17-Pin 4 (SP-) will always be
connected to the audio section.
Four Wire Intercom Configuration: Two separate pairs (four wires) are used for
both the call function and audio in the four-wire configuration. In this mode, J23
receives no jumpers.
3 Wire Intercom Configuration: This mode requires two conductors for audio and
one additional conductor for the call function. This mode uses a common ground for
both audio and the call function (SP-). Jumper pins 3&4 (bottom 2 pins) of J23 and
connect H1, SP+ and SP- .
2 Wire Intercom Configuration: This type of intercom system has both the Call
Function and audio sharing the two conductors. Jumper pins 3&4 (bottom 2 pins) and
1&2 (top 2 pins) of J23 and connect the two conductors to SP+ & SP-.