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CHAPTER 4: Troubleshooting
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,
Cat5 switches, Cat5 distribution amps, or Multi-output
transmitters, the serial signal is a unidirectionally broadcast
mode only. In this mode, all other MultiView™ CAT5 Video
System devices must be the simplex serial type.
• The last device in a T4 transmitter or daisy chain configuration
must be a receiver unit with a terminated serial board.
See Appendix C for Serial board settings.
• For SA units a special unterminated version must be used
between transmitters and the last receiver with a standard End-
Of-Line unit installed at the end. SA units cannot be terminated/
unterminated in the field. This does not apply to SAP units.
• SA/SAP units have a fixed baud rate of 9600 bps and use 3 wire
(TX,RX,GND) signals only.
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
MultiView CAT5 UTx Universal transmitter has been designed
with full DC restoration capability. This problem is easily solved
via a simple switch setting in the UTx Transmitter. Please refer to
the UTx 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, an
AK600 can only daisy chain within 600 ft of the transmitter.
It is possible to daisy chain out of a short range receiver into a longer
range receiver to increase the range. For example, over 600 ft an
AK600 can be daisy chained into an AK1200 which allows for daisy
chaining to 1,200 ft.
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.
With the exception of SAP units, serial communication in a daisy
chain is one way simplex.
