Multitech MMH900, User Manual

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Appendix I - Testing Your MMH 2834
I.7 Digital Loopback Test (Loc/Man) Sync Mode
This test must be run when you have a data connection with another
modem. If a Local Analog Loopback Test resulted in errors, and this test
passes without errors, then the problem exists in your computer-to-
modem connection. In Digital Loopback Test (local/manual) mode, data
passed from the remote modem’s transmit circuit are looped back from
the local modem and are received at the remote modem’s receive circuit
(multiple upper case “U” characters in Figure I-5).
First make certain that you are set up for Synchronous operation by
displaying the composite link configuration and ensuring that the link
format is sync. Sync mode is set using the $M(Sync) command. Once
you receive an OK message from your modem (if responses are
enabled), the local modem is placed in Digital Loopback mode.
Digital
DIP-Switch #9
UP; Answ/Orig
Switch Toggled
to Answ
position when
On-line
UUUUU
UUUUU
Computer or Terminal Local MultiModem Remote MultiModem Computer or Terminal
Analog Digital Analog
Figure I-5. Digital Loopback Test (local/manual)
(Synchronous Mode)