Avocent LongView x30 Guide D'installation page 33

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23
Appendices
Appendix F: Advanced Questions
Is there anything I should do to optimize the video quality for my particular cable?
LongView extender automatically tunes its circuits to optimize video performance for your specific
cable length. However, for optimum performance at the maximum distances, particularly for high
video resolutions, Comtran 2819 cable is recommended.
CAT 5 cables have different twists-per-inch rates for the four pairs of wires within a cable to reduce
crosstalk. These rates vary by manufacturer. In cases involving maximum length cables and high
video resolutions, some manufacturers' cable may cause the red, green and blue colors to be
"misaligned" such that a vertical white line shows up as a vertical line of two or three colors in
parallel. In this case, you may be able to improve the video by making your CAT 5 cable more
closely match Comtran cable by using a special adaptor available from Avocent.
NOTE: Before modifying your cable, connect your monitor directly to your server to verify that any misalignment
is not caused by the server or the monitor. If the problem persists, contact the manufacturer of the monitor or the
video card for assistance in improving your video quality.
If the problem was solved when the monitor was directly connected to the server, you may have a
power problem.
What signals and data rates does LongView extender's serial port support?
The serial port on LongView extender is intended to extend a standard server COM port. A COM
port uses serial asynchronous data (such as no clock signal) along with some handshake lines.
LongView extender provides Transmit Data (TD), Receive Data (RD), Request-to-Send (RTS),
Clear-to-Send (CTS), Data Terminal Ready (DTR) and Data Set Ready (DSR).
LongView extender's serial port is specified for applications up to 19.2 Kbps, but it may work at
rates up to twice that, depending upon your server's COM port and your serial device. TD and RD
are sampled at a high rate at one end and recreated at the other end with a slight amount of jitter. If
your equipment is tolerant of jitter, you may be able to use LongView extender at rates higher than
the specified 19.2 Kbps. There are no configuration straps or switches for data rate. Just connect
your equipment as if you were connecting your serial device directly to the COM port.
The only COM port signals not supported by LongView extender are Data Carrier Detect (DCD)
and Ring Indicator (RI), which are seldom used. Consult the manufacturer of your serial device and
communication software to determine if you need DCD or RI. If so, you may be able to use the
LongView extender's extension of CTS or DSR in its place by building an adaptor at each end (one
between the server and the LongView transmitter, the other between the LongView receiver and
your device). A similar adaptor is required between the LongView receiver and the serial device.