Specifications
Chapter 3 Operation  FOM-40 Installation and Operation Manual 
3-2  Turning On FOM-40   
Table 3-1. FOM-40 Front Panel Controls and Indicators 
Name Type  Function 
PWR  Green LED  ON – Power is on. 
RTS  Yellow LED  ON – The DTE activates Request To Send. 
TD  Yellow LED  ON – Steady SPACE is being transmitted. 
Blinks – Data is being transmitted. 
RD  Yellow LED  ON – Steady SPACE is being received. 
Blinks – Data is being received. 
DCD  Yellow LED 
ON – A valid receive signal is present. 
TEST  Yellow LED  ON – FOM-40 is in one of three loopback modes, or the PATT 
pushbutton is pressed. 
ERR  Red LED  ON or blinks if errors are present. 
DIG  Pushbutton  Pressing the digital loopback pushbutton causes the local 
FOM-40 to loop received data to its transmitter (see Figure 4-3). 
ANA  Pushbutton  Pressing the local loopback pushbutton causes the local FOM-40 
to loop its transmitter output back to its receiver 
(see Figure 4-1). This loopback may also be activated from the 
DTE when SW5/5 is set to EN (excluding X.21, G.703 and 
Ethernet interfaces). 
REM  Pushbutton  Pressing the remote digital loopback pushbutton causes the 
remote FOM-40 to loop received data to its transmitter 
(see Figure 4-2). This loopback may be also activated from the 
DTE when SW5/5 is set to EN (excluding X.21, G.703 and 
Ethernet interfaces). 
PATT  Pushbutton  Pressing the PATT switch causes FOM-40 to send and receive a 
test pattern. If errors occur, the ERR indicator lights up. 
SW5/5 dip switches control the LLB and RLB activation only from the DTE interface. 
The jumper settings do not affect the ANA and REM pushbutton operation. 
3.2 Turning On FOM-40 
When power is connected to FOM-40 it turns on, the PWR indicator lights, and 
remains lit as long as the unit receives power. 
FOM-40 requires no operator attention once installed, except for occasionally 
monitoring front panel indicators. Intervention is required only when the modem 
is configured to new operational requirements, or diagnostic tests are performed. 
Note 










