Specifications

MX-2100/2104 Installation and Operation Manual Chapter 5 Diagnostics
Diagnostic Tests 5-11
Local Main Link Modem Loop - Loop 3
The main purpose of the main link modem loop 3 is to check the connections
between the KML module and the local modem. Usually, this loop is activated
after the remote main link loop fails but both the local and the remote MX-2100
units successfully pass the local main link loops. If this loop is successful, the next
loop to be performed is the remote main link modem loop, loop 2.
Therefore, as a rule, perform loop 3 only after successfully performing a local main
link loop on the local MX-2100 unit.
Main Link Loop 3 – Signal Path
When loop 3 is activated on a modem that supports this function, the MX-2100
transmit signal is returned by the local modem on the receive path. The loop signal
path is shown in Figure 5-3.
Local Modem
Remote Modem
User or Test
Equipment
Local
MX-2100
User or Test
Equipment
Remote
MX-2100
Figure 5-3. Main Link Modem Loop 3, Signal Path
Main Link Loop 3 – Normal Indications and Fault Location
• The TEST indicator of the MX-2100 lights.
• The TXD and RXD indicators of the local MX-2100 must light, and the LOCAL
SYNC LOSS indicator must be off. If not, the connections to the modem, or
the modem itself, are defective.
Remote Main Link Modem Loop - Loop 2
The main purpose of the main link modem loop 2 is to check the link between the
two modems that serve the main link. As a rule, perform loop 2 only after
successfully performing loop 3 on the local MX-2100 unit.
Main Link Modem Loop 2 – Signal Path
When loop 2 is activated on a modem that supports this function, the remote
modem returns the receive signal toward the local modem, therefore the local
MX-2100 transmit signal is returned to the receive path.
The loop signal path is shown in Figure 5-4.