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Chapter 4: System connection
4.1 Summary
HCS-3900 Economical Digital Conference System has a
simple but efficient structure. Its installation is simple,
quick and does not need special training. Daisy-chain
connection is adopted between conference units as well
as to CMU via dedicated extension cable.
TCP/IP protocol is adopted for Ethernet connection
between the CMU and the PC. As a result remote control
and remote update can be achieved. Access the CMU
through Web page, operator can control the conference
neatly.
In this chapter, the connections of HCS-3900 Economical
Digital Conference System are introduced by diagrams.
4.1.1 Connection principles
The Conference Main Unit forms the core of the entire
conference system. It provides power supply to all
contribution units and serves as key component to link
system hardware to Web page control.
Since contribution units are powered by the CMU, thus,
the total number of contribution units in any installation is
limited by the maximum power handling capacity and
control capacity of the HCS-3900M CMU (refer to table
4.1). In one system, up to 255 units can be connected by
adding HCS-3900ME extension unit (in them up to 100
chairman units can be connected, but only 1 chairman
unit has control facilities). Any delegate unit can be set as
VIP unit, the total number of VIP units being limited to 32.
As long as the number of active microphones in the
system is less than 6 (including chairman, delegate and
VIP), a VIP microphone can be activated freely (except
Voice mode).
The CMU can work alone to achieve basic control
functions; when through Web page to access the
HCS-3900MA/MB, more powerful and versatile
management and control functions are accessible.
4.1.2 Connection cables
HCS-3938 series conference unit is equipped with a 1.5
m 6P-DIN standard plug cable and a 0.6 m 6P-DIN socket
cable. When the units are connected one by one, connect
the first unit to the outlet connector of the CMU, and
following connect the 6P-DIN standard female connector
on the 0.6-meter cable of the unit to the 6P-DIN standard
male connector on the 1.5-meter cable of the next unit -
thus contribution units are daisy-chain connected.
CBL6PS extension cables can be used between
contribution units and the CMU.
4.1.3 Extension cable
If the distance between the CMU and the contribution unit
or one contribution unit to another one exceeds 2.1-metre,
an extension cable is needed. Due to the voltage drop in
the extension cable caused by the ohmic resistance, the
number of contribution units available for each outlet
connector will be reduced according to the length of the
cable connected to trunk-line. The relationship is
described as table 4.1:
The extension cable connected between the CMU and
the first contribution unit carries the current of all
subsequent units and influences at the same time the
maximum possible load of the CMU. However, the
influence of a cable connected between the last two
contribution units, is insignificant because it carries only
the current for the last unit.
Table 4.1 Quick lookup table of HCS-3900M CMU/EMU load capability
（
unit
：
piece
）
The extension cable length between the CMU(EMU) and the first
Congress Unit connected to the socket
Type No.
20 m
40 m
60 m
80 m
HCS-3900MA 25
23
22
21
HCS-3900MB 25
23
22
21
HCS-3900ME 18
16
14
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