30
SYNC/ASYNC FIBER OPTIC MODEM
Table 4-1 (continued). Fiber Optic Modem’s Front-Panel Controls and
Indicators
Item No. Name
Type
Function
9
ANA
Pushbutton
The ANA (Analog) loopback (V.54
Loop 3) switch causes the local FOM-
20 to loop its transmitter output back to
its receiver (see
Figure 5-1
). This
loopback may also be activated from
the DTE when the LLB strap is set to
EN.
10
REM
Pushbutton
The REM (Remote) digital loopback
(V.54 Loop 2) switch causes the
remote Fiber Optic Modem to loop
received data and clock signal back to
its transmitter (see
Figure 5-2
). This
loopback may also be activated from
the DTE when the RLB strap is set to
EN.
11
PATT
Pushbutton
The PATT (Pattern) switch causes the
Fiber Optic Modem to send and
receive a 511 test pattern. If errors are
encountered, the ERR LED lights up or
blinks.
4.3 Initial Operation and Basic Checks
4.3.1 P
OWER
-O
N
P
ROCEDURE
The Fiber Optic Modem turns on as soon as you connect power. The POWER
indicator lights up and remains lit as long as the Fiber Optic Modem receives
power.
NOTE
Check first that none of the front-panel pushbuttons are pressed (down).
