Verilink Productivity 500 (34-00236) Product Manual - Manual (Page 76)

Page 76 500 TA Test Mode Operation
Local Loopback Test &T1
Local loopback loops data from the local PC back to the PC so that whatever
the PC sends is echoed back (
Figure 7 ). Also the RTS pin is echoed on the CTS
pin and the DTR pin is echoed on the DSR, DCD, and RI pins. Run this test if
you are encountering data errors before and after data calls are placed. This test
is useful in diagnosing the PC and the 500 TA. The DTR Reset (&D3) option
will not affect this test mode.
Figure 7 Local Loopback
To initiate the test, enter AT&T1 from the PC or terminal. The 500 TA may be
online or offline when the test is initiated. Any protocol, mode, and DTE rate
may be used. Data from the local PC will be echoed back to the sender and the
CTS pin follows the RTS pin and the DSR, DCD and RI pins follow the DTR
pin. The PC portion of the test verifies the operation of the PC, the PC cable the
PC interface in the 500 TA and of the data buffers in the 500 TA. The test is
successful if the data is successfully echoed back to the sender. A BERT device
can be helpful in checking for data errors.
The test is terminated by using the AT '+++' escape sequence.
Digital Loopback Test &T3
Digital loopback loops the ISDN B-Channel data normally sent to the local PC
(
Figure 8 ). Any B-Channel data received by the 500 TA is processed by the
rate-adaptation protocol, and then echoed back out the B-channel to the send-
ing unit. This test is useful in diagnosing the PC, 500 TA, switch ISDN line,
and remote unit. Run this test if you are encountering data errors after a call is
placed successfully.
To initiate the test, enter '+++' to escape to command mode and AT&T3 from
the PC. The 500 TA must be online when the test is initiated (a call must be
placed) before the unit can loop B-channel data. Any protocol, mode, and DTE
DTE
ISDN
Interface
DTE
Interface
ISDN
Line
ISDN
Receiver
ISDN
Transmitter
Protocol