15
CHAPTER 2: Introduction
2.1.6 V.54 D
IAGNOSTICS
You can activate V.54 loops with either the front-panel pushbuttons or Pins 18
and 21 of the V.24/ RS-232 interface. The pushbuttons, Pin 18, and Pin 21 can
be enabled or disabled separately by the SWITCH, PIN 18, and PIN 21 jumpers,
respectively.
When you use the LDM-MR19.2 as a tail end to a DDS network, set the V.54
DELAY jumpers of the modems located close to the DDS network to ON to
prevent multiple loopbacks. The DELAY switch prevents the last modem from
receiving the complete V.54 data sequence and being induced into a loop. V.54
is required only for operation in synchronous mode.
NOTE
The V.54 DELAY jumper must be set to OFF when you operate
in asynchronous mode.
2.2 Applications
Figures 2-2 through 2-5 on the next two pages illustrate the LDM-MR19.2 in various
configurations.
(text continues on page 18)
