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MINIATURE 2-CHANNEL STATISTICAL MULTIPLEXOR
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
(1) Local composite channel loop
When the local composite channel loop is connected, the composite channel
data transmitted by the local Multiplexor is applied to the receive line of the local
Multiplexor, and the communication link is disconnected (this causes the remote
Multiplexor to lose frame synchronization). All the data arriving from the remote
Multiplexor while this loop is connected is lost.
This loop tests the complete local Multiplexor.
As long as the loop is connected, the SYNC indicator of the local Multiplexor
must light continuously. If they do not, this indicates a local Multiplexor problem.
Sub-channel activity indicators light according to traffic; the lighting of the OVF
indicator means that Multiplexor buffers are full because of flow control problems
caused by the equipment connected to one of the local sub-channels.
(2) 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 Multiplexor. All the data arriving from the
remote Multiplexor 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.
