User guide

107
Chapter 7 - Troubleshooting Procedures
7.6 Local Modem and Communications Line
Testing
After determining that the channel-device-to-MultiMux portion of the
multiplexer network is operating properly, the next steps are to check the
operation of the local modem, the communications line and the remote
modem. By performing the procedures in Table 7-3, the MultiMux can
send data (keystrokes) from the channel device and have the data
echoed through the composite link and remote modem back to the
channel device’s monitor.
The procedures shown are generalized in that they apply to testing both
the analog and digital segments of the remote modem. The following
table shows the setting of the two modems to test the two network
segments.
Table 7-3. Modems and Communications Line Testing
Procedure
1 If external modems are used, set them to test the desired network
segment according to the Figure 7-1. Refer to the modem
documentation for proper test procedures.
2 If internal MultiMux modems are used, place them in the proper
mode by executing the appropriate test mode (refer to Figure 7-1) by
having the operator at the other end of your network enter the
following on his or her supervisory console:
AT&x (hit Return)
x equals T5 for Digital Loop, T6 for Remote Analog Loop.
Table 7-3. Modems and Communications Line Testing Procedure
(cont.)
Testing Local Modem Remote Modem
Segment Setting Setting
Communications Normal Mode Remote Analog
Line and Remote Loop
Analog Circuitry
Communications Normal Mode Digital Loop
Line and Remote
Digital Circuitry