Black Box MX880A, Руководство пользователя

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14
ASYNC/SYNC FIBER OPTIC MULTIPLEXOR
5.3.2 R
EMOTE
L
OOPBACK
Remote loopback sends data back from the remote receiver to the remote
transmitter, which checks all local digital circuitry as well as both the local
and remote analog interfaces, main channel link, and remote digital receiver
section.
To activate the remote loopback test, press the “RLB” pushbutton located
on the front panel of the multiplexor (see Figure 5-1). If both the local and
remote units are operating properly, the yellow Test LEDs should be lit on
both units and all other LEDs should be off.
NOTE: When either the local or remote loopback test is performed, the
following signals at the remote unit’s subchannels are OFF (negative voltage):
• Receive Data (Circuit 104)
• Clear to Send (Circuit 106)
• Receive Line Signal Detector (Circuit 109)