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Intellivox HP series Installation Manual Rev 1.2
®
NETWORK CONNECTION
The RS-485 network connection should be wired if the
Intellivox is to be constantly monitored in operation.
The RS-485 interface permits multiple units to be
"daisy-chained" in parallel, so that all units are controlled
by the same PC. In such a system, each Intellivox must
have its own unique network address; this is determined
via WinControl for each individual Intellivox.
unit 3
unit 2
A
B
Y
Z
DGND
DGND
to other devices
Fig.10 RS-485 "daisy-chained units".
The network connection uses a 5-pin, 3.81 mm-pitch
screw-terminal connector, and should be wired as shown
in the table and diagram below:
PIN NO.
1
2
3
4
5
Z B
Y
DGND
NETWORK CABLE
Twin twisted pair,
individually shielded
Fig.11 RS-485 network connection.
201601/IvxHPDS_v1.2
unit 1
A
A
B
B
Y
Y
Z
Z
DGND
host
Y
Z
A
B
DGND
USE
DGND
Y (Data Tx +)
Z (Data Tx -)
B (Data Rx -)
A (Data Rx +)
A
Note that two-pair, individually-screened cable should
be used for RS-485 communications. The transmit (Tx)
and receive (Rx) balanced data lines must be wired via
their own twisted pairs. Cat 5 (or better) type UTP or
FTP cable is NOT suitable. Please refer to the Appendix
section (on page 24) at the end of the manual for cable
specifications.
The maximum cable length over which the network
connection will operate reliably depends on the cable type
and the baud rate used. With good quality cable, a safe
maximum figure (at 19.2 kbaud) is 2000 m. If the distance
is significantly greater than this, a network repeater will
be required.
Further information on the RS-485 network can be found
in the manual for the USB to RS-485 converter and in the
WinControl Help files.
Before connecting multiple devices to the same
network subnet, ensure that their network
addresses do not overlap. Each device should
be set to a unique network address (determined via
WinControl).
In some installations, it is normal practice to
disconnect the RS-485 network at the XLR5
connector on the USB to RS-485 converter at
the host (computer) during normal operation. This removes
the possibility of extraneous data being inadvertently
transmitted over the network. In such a situation, the
converter is only reconnected when system maintenance
or checks are required. Disconnecting from the converter
in this way leaves the Rx lines of the devices unterminated.
In most situations this does not present any problems, but
with a large network in a hostile EMC environment, it is
recommended that the host Y and Z lines (host device Tx/
Intellivox Rx) are terminated in a 100 ohm resistor for
normal operation. This can be easily achieved by plugging
the XLR5 female connector into a spare male connector
with the resistor on the appropriate pins. This termination
can then be removed and the converter reconnected when
necessary. (If there is any doubt about which pins should
be terminated, shorting all five pins will generally be
equally effective.)
13
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