Specifications

LEDs
LEDs
The front panel of the modem provides the LEDs shown in Table 2-7.
Table 2-7. Modem LEDs
LED Color Description
Power
Green Power
RTS
Yellow Request To Send
CTS
Yellow Clear To Send
TxD
Yellow Transmit Data
RxD
Yellow Receive Data
DCD
Yellow Carrier Detect
ALB
Red* Analog Loopback
DLB
Red* Digital Loopback
* When the modem is in remote loopback, both the ALB and DLB LEDs go ON.
Loopback Control Switch
The front panel of the modem has a push button for initiating the following loopback diagnostic tests:
 Local analog loopback  started by pressing the button one time.
 Local digital loopback  started by pressing the button two times.
 Remote digital loopback  set the local modem’s RTS signal to low. Then press the remote modem’s
diagnostics button three times and raise the local modem’s RTS signal to start the test. The ALB and DLB
LEDs go ON when the modem is in remote digital loopback. This test is only available in Fast Poll mode only.
Figure 2-6 illustrates these three diagnostics.
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