Specifications

FOM-40 Installation and Operation Manual Chapter 5 Troubleshooting and Diagnostics
Loopback Tests 5-3
Remote Digital Loopback (RLB)
The remote digital loopback (RLB) test checks the performance of the local and the
remote FOM-40 units and their connecting lines. The remote digital loopback sets
a loop at the remote FOM-40 unit from the DTE connected to the local unit
(see Figure 5-2).
Local
DTE
Remote
DTE
Link
Interface
Link
Interface
Transmit
REM
Pressed
Receive
Receive
Local FOM-40 Remote FOM-40
Transmit
Data
Data
Clock
Clock
Figure 5-2. Remote Digital Loopback
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To activate the remote digital loopback:
1. Press the REM pushbutton on the local FOM-40 front panel.
The TEST LED on each FOM-40 front panel lights up. The receive output
of the remote modem is looped back to the transmitter.
2. Perform the BER test as explained above for the local analog loopback test.
If the local analog loopback test described above was successful for both the
local and remote modems, and an error occurs during the BER test, the line or
the line circuits of the local or the remote unit are not operating properly.
3. After completing the test or correcting the fault, press REM pushbutton again
to restore it to the OFF position.