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6.2 Description of Test Loops
Whenever a test loop is on, the TEST indicator will light and traffic will be
disrupted.
6.2.1 L
OCAL
L
OOPS
Local composite-channel loop
When the local composite-channel loop is connected, the composite-channel
data transmitted by the local MiniStat-Four is applied to the receive line of the
local MiniStat-Four, and the communication link is disconnected (this causes
the remote MiniStat-Four to lose frame synchronization). All the data arriving
from the remote MiniStat-Four while this loop is connected is lost.
This loop tests the complete local MiniStat-Four.
As long as the loop is connected, the SYNC indicator of the local MiniStat-Four
must light continuously. If it doesn’t, this indicates a local MiniStat-Four problem.
Sub-channel activity indicators light according to traffic; a flashing ERR indicator
means that the MiniStat-Four buffers are full because of flow-control problems
stemming from the equipment connected to one of the local sub-channels.
Local sub-channel loop
When a local sub-channel loop is connected, the local transmit data is returned as
receive data on the same sub-channel. The local data is also multiplexed into the
transmit data stream sent to the remote MiniStat-Four. All the data arriving from
the remote MiniStat-Four sub-channel while this loop is connected is lost.
As long as the loop is connected, the sub-channel activity indicator lights according
to traffic. The equipment connected to the sub-channel must receive its own
transmit data without errors. Failure to do so usually indicates problems with the
sub-channel connection cable or with equipment connected to that sub-channel.
6.2.2 R
EMOTE
L
OOPS
Remote composite channel loop
When the remote composite-channel loop is connected, the composite-channel
data transmitted by the local MiniStat-Four is returned from the remote MiniStat-
Four after regeneration but without any other processing. Any data transmitted
from the remote MiniStat-Four sub-channels is lost during loop connection.
CHAPTER 6: Troubleshooting
