Solutions to Common Problems
9
Problem:
Serial communication doesn’t work correctly.
Solution:
Are the serial devices connected properly? Are the serial
parameters correct for source/destination devices?
Are the serial cables terminated correctly? If a null-modem cable
is used, it must be placed at the receiver end.
When using RS-232 transmitters or receivers in daisy chains, CAT
5 switches or CAT 5 distribution amps, the serial signal is a
unidirectionally broadcast mode only. In this mode, all other
Cobra
CAT 5 Video System devices must be the simplex serial
type.
The last device in a transmitter-to receiver or daisy chain
configuration must be terminated. The
R1300A
can be used as
either a “middle unit” or an “end unit”; the termination switch is
located on the front of the unit.
The
R1300S2
can only be used as an “end unit” in a transmitter-
to-receiver or daisy chain configuration. The
R1300S2M
Receiver must be used as a “middle unit” in a daisy chain
configuration. Using the
R1300S2
as a “middle unit” will prevent
audio and serial signals from operating correctly.
Using the
R1300S2M
as an “end unit” will prevent audio and
serial signals from operating correctly.
R1300S2
/
R1300S2M
Receivers cannot be modified in the field.
Problem:
“Green shift” or “green washout” on multimedia signals.
Solution:
The standard video/serial model is designed to function with DC
coupled signals in which the black level is referenced to 0 volts.
Nearly all VGA cards function this way. Some media servers,
however, provide AC coupled signals and can cause a green color
shift in the video. This is a result of the sync clamping on the red
and blue channels of the video/serial model. For five-component
(RGB/H&V) AC coupled video, the
Cobra
CAT 5 transmitter has
been designed with full DC restoration capability. This problem is
easily solved via a simple switch setting in the
Cobra
Transmitter.
Refer to the
Cobra
Transmitter user manual.
Problem:
Notes on Daisy Chaining:
Solution:
When daisy chaining, the maximum cable distance is not
increased beyond the rated distance of the receiver used. For
example, the maximum distance from a transmitter to the last
R1300S2 Receiver in a daisy-chain is 1300 feet. A maximum of
12 units may be daisy chained together. If a unit in the middle of
the chain loses power or is disconnected from the chain, all units
after this will lose signals. All serial communication in a daisy
chain is one way simplex.
Summary of Contents for Cobra R1300A
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