Remote Digital Loopback Testing (At&T6, At&T7); Granting A Digital Loopback Test Request; Canceling All Digital Loopback Test Requests - 3Com Courier Reference

15-6 C 15: T
HAPTER ESTING THE CONNECTION
Remote Digita
Loopback Testing
(AT&T6, AT&T7)
Granting a Digital
Loopback Test
Request (AT&T4)
Canceling All Digital
Loopback Test
Requests (&T5)
The remote digital loopback test, verifies the condition of both devices
and of the phone line. Data flow is shown in the figure below.
Transmitter
TX
To DTE
RX
Receiver
Local
Data Flow During Remote Digital Loopback.
The request for and granting of remote digital loopback testing requires
that both devices use ITU-T V.22 standard signaling. If the remote device
does not have the capability or is not set to respond (with
get an ERROR result code.
There are two remote digital loopback options.
If you want to
Send keyboard data to the modem and verify it when it is
returned over the phone lines and to your screen
Have the modem send its internal test pattern and return
an error count to your screen
Example: Sending
AT&T6
returning it over the phone lines and displaying it on your screen.
Using causes the Courier V.Everything modem to grant a remote
AT&T4
device's request for a remote digital loop-back test.
Using cancels
AT&T5 AT&T4
acknowledge remote digital loopback test requests. This is the default so
that your Courier V.Everything modem isn't subject to another user
calling and tying up your Courier V.Everything modem without your
permission.
Telco Telco
will verify keyboard data sent to the modem by
, and the Courier V.Everything modem fails to
Transmitter
To DTE
Receiver
Remote
), you will
AT&T4
Command
AT&T6
AT&T7
TX
RX