Diagnostics & Loopbacks
A number of diagnostic configuration options are available. It is possible to loop back the
data channels and the composite link, both locally and remotely, to test for correct operation.
The configuration procedure is detailed in the Use and Configuration section starting on page
14.
LOCAL COMPOSITE LOOPBACK loops back the composite link of the local multiplexer,
i.e. the unit to which a VDU being used to perform set-up is connected. Whilst the composite
link on the local multiplexer is being looped back, incoming data from the remote multiplexer
is ignored.
When REMOTE COMPOSITE LOOPBACK is selected the composite link is looped back at
the remote unit which returns data to the local multiplexer, data inputs to the remote
multiplexer are ignored.
CHANNEL LOOPBACKS, which may be LOCAL or REMOTE, are not intrusive to other
data channels.
Loopbacks are not bilateral and may only be set at one end of the link for one channel at any
time.
Self Test Procedure
The multiplexer automatically initiates a
Self Test
procedure when powered on. The
progress of the self-test is indicated by the LEDs on the front panel and by a scrolling display
(see below) if a terminal is connected for configuration.
******************** SELF TEST *******************
ROM TEST PASSED
RAM TEST PASSED
LED TEST
CTC READ/WRITE TEST PASSED
SIO READ/WRITE TEST PASSED
INTERRUPT DAISY-CHAIN TEST PASSED
INTERNAL CLOCK/P.L.L. / TLOK / FLASH TEST PASSED
CHANNEL CLOCK TEST PASSED
**************************************************
