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CHAPTER 5: Operation
5. Operation
Once you have configured each Async Short-Haul Modem MP properly and
connected it, simply plug in the AC power adapter to get it running; there is no
power switch on the Modem. You can monitor the Modem’s operation using the
front-panel LED indicators and built-in loopback test modes.
5.1 LED Indicators
The Modem incorporates six front-panel LEDs that show status:
• The power LED lights when AC power is applied to the modem.
• The loopback test LED lights when the loopback test switch has been pressed
and is in a test mode.
• The tri-state TD and RD indicators blink red and green with data activity. Solid
red indicates a low RS-232 logic level and no color indicates no activity on the
line. Note: RS-232 devices idle in a low state, so the LED will glow red if the
connections are correct and the RS-232 device is in an idle state.
• The control in and control out indicators light red for a "low" signal and green
for a "high" signal. The specific pin number associated with these indicators
will vary according to the switch settings you have selected (see
Chapter 3
).
5.2 Loopback Test Modes
Select the test modes by pressing the Loopback Test switch. When the Modem is in
loopback mode, the Loopback Test LED will glow red. Two tests are possible using
this switch: Local Analog Loop (LAL) and Remote Analog Loop (RAL).
5.2.1 L
OCAL
A
NALOG
L
OOP
The first test mode is Local Analog Loop (V.54 Loop 3). Any data sent to the local
Modem in this mode will be echoed back (returned) to the user device. For
example, characters typed on the keyboard of a terminal will appear on the
terminal screen (see Figure 5-1 on the following page). If characters are not
echoed back, check the connections between the user device and the Modem.
Wire the units according to the instructions in
Chapter 4
.
