Media Oriented Systems Transport (Most)

Media Oriented Systems Transport (MOST)






NOTE: Items 1, 2, 3, 8 and 9 will always be present. The remaining items are optional and/or market specific.






Overview

The basic guidelines are covered in the description and operation section, such as not attempting to repair fibre optic cables,

but additional precautions include:
- Do not touch the exposed ends of the optical fibres (grease from skin can contaminate the fibre)
- Whenever the fibre optic cable is disconnected, cover the connectors to prevent dust contamination
- Do not expose the fibre optic cable to heat
- Do not bend the fibre optic cable through less than a 25 mm (one inch) radius
- Do not use laser pens to test the fibre optic cable's ability to pass light


MOST Diagnostic Tools

There are two dedicated tools for testing the MOST system:






MOST tester. The MOST tester is connected to the MOST network in place of a control module. It will confirm receipt of any
existing MOST signal and transmit it to the next control module on the network. Perform the following tests to validate the
operation of the MOST tester. GO to Pinpoint Test A.






MOST prism. The MOST prism is connected in the same way as the MOST tester but will simply reflect any existing signal
onward to the next control module. Using the MOST prism before or after a long run of harness may cause a ring break as a
good signal may be too weak after travelling the extended distance. Also, the MOST prism will pass light in either direction so
will not detect reversed MOST terminals elsewhere in the network. For these reasons, the MOST tester is the preferred tool
and should be used unless limited access does not permit it


MOST Ring Break Indication

A ring break in the MOST network is indicated by the Touch Screen (TS) soft keys being greyed out and inoperative. Possible causes of ring breaks are listed in the symptom chart