Verilink ConnecT 56K DSU (896-502110-001) Product Manual - Manual (Page 46)

Operation
3-16 ConnecT 56K DSU User Manual
Figure 3-6 Status Display
Menu map
2=TEST/1= LOCAL UNIT/2=LOOP ONLY (RT)/Displays
Operation
Follow standard operating procedures. When 2=LOOP ONLY (RT) is
flashing: Press the Enter button resulting in the system briefly displaying
“Please Wait” after which it displays the first of the test results.
LOCAL LOOP (RT)
Continue with operational procedures described for DTE & LOOP (LL).
3 = DTE ONLY
The DTE ONLY test provides a method for testing both the DTE interface
drivers and receivers of the local ConnecT 56K DSU plus its loop
transmitter and receiver. For this test, the loop transmit data is connected
to the loop receive data at a point close to the physical network interface.
The data is then sent back towards the DTE. The transmit circuit to the
network is terminated in a zero condition for this test. A block diagram
illustrating the loop back point and the signal paths for this test is shown
in Table A-3, “DTE Only Test Diagram,” on pageA-9.
Test patterns from an external BERT tester are routed through the DTE
interface section of the ConnecT 56K DSU and then to the output of the
loop transmitter section where the signal is encoded for transmission.
Instead of being coupled onto the physical transmit circuit of the network,
the output of the loop transmitter is coupled back to the loop receiver
input where the signal is then decoded and returned to the BERT tester
where the serial receive data stream is checked for any bit errors.
This test is used to verify proper operation of both the DTE and loop
interface sections of the local ConnecT 56K DSU.
2=LOOP ONLY (RT)
LOCAL LOOP (RT)
LOOP 56K
DTE 56K SYNC
TR
OFF
SR LLB RLB
OFF OFF OFF
UNIT IN TEST
LOOP IS NORMAL