Test Cables - Multitech MMH900 User Manual

Chapter 6 - Operating Procedures
retransmits needed to get the data through can indicate a line problem.
Comparing the blocks received and receive block errors indicates the
same problem from the other end of the link. The comparative numbers
that you might encounter could be 10,000 blocks transmitted (or
received) with 500 or 1000 retransmits (or receive block errors).
Link Alarms simply tell you that there are some sort of problems on the
link. You will find that the Link Alarm numbers will correspond to the
Retransmit and Receive Block numbers. Specifically, a Link Alarm
means that it has been 10 seconds since the MultiMux has received an
acknowledgment. Normally three acknowledgments will be received
during a 10 second period.
The Remote Down entry means that a MultiMux has sent data 30 times
and could not get it through (the link has been broken).
The other entries in the composite status report do not apply to link
problems.
7.3

Test Cables

If you are using the MultiMux internal composite link modem, 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 MultiMux
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 modem's signal to itself (analog
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 link communications, refer
to its documentation for testing procedures.
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