Multi-Tech Systems MMV1600 TestCables, TroubleshootingGuide, Data Troubleshooting Guide

7.3

TestCables

If you are using the MultiMux internal DSU, there are two test cables provided which can be used to help checkout your system (refer to Figure 7-1). The MultiMux Test cable is a special back-to-back composite link test cable that can connect your two MultiMuxes locally before installing them using a phone line. This cable will allow you to verify operation of all aspects of the MultiMux prior to actual installation. The second test cable is the Composite Link Loopback cable. Its function is to loopback the DSU signals to itself (loopback) so that you can check the function of the MultiMux while installed without having to use the composite link phone line. If you are using an external synchronous modem for the link communications, refer to its documentation for testing procedures.

If you have any problems in performing these procedures, contact Multi-Tech’s Technical Support department for assistance, refer to Chapter 8.

Using the Test Cable

Test Cable

MultiMux MultiMux

Internal Composite

Connector

Note: Used locally before installation to verify operation of entire system except compolsite link.

Using the Composite Link Loopback Cable

MultiMux

Internal Composite Connector

Composite Link

Loopback Cable

MultiMux

Note: Initiate Downline Load must be off for loopback testing.

Figure 7-1. Off Line Test Modes

7.4

TroubleshootingGuide

The following guides are set up as a series of possible conditions, causes and suggested fixes or steps in finding the failing unit. Because of the different manufacturer’s equipment involved in typical multiplexer networks, you may encounter “finger pointing” as to who is at fault. Who is at fault is not as important as getting you back on line as soon as possible. The intent of the following guides are to indicate the most probable cause of specific error conditions, but, since similar conditions may account for a number of different failures, the following guides are just that: a guide to troubleshooting.

The parts of your mux network are:

Data Channel

•Channel devices (printers, terminals, pc’s, etc.)

•Channel Communications (RS232 cabling, asynchronous modems, etc.) Voice/Fax Channel

•Telephones and fax machines

•Station side of PBX

•E&M trunk

Control units

Composite Link

•Digital composite link communications line with internal or external DSU

•External Synchronous link modems

•Composite link communications line (4-wire non-loaded metallic wire)

Once you have found the probable cause of your problem, refer to the specific manual chapter for additional help, or contact Multi-Tech Technical Support (refer to Chapter 8).

Table 7-1. Data Troubleshooting Guide

Condition	Possible Cause	Corrective Action
Supervisory Console	1. Communications software	1. Install communications software on