COURIER HIGH SPEED MODEMS
Ending Testing with the Test Pattern
Pressing
any
character
key
cancels all test
pattern
tests
and
hangs
up
the
modem.
If
you
used
Register S16,
be
sure
to reset
Register S16 to
Data
mode
when
you
reset
the
modem
to its
error
control defaults, for example, ATZ
or
AT&M4S16=0.
REMOTE DIGITAL
LOOPBACK-S16=8
Responding Modem
The
responding
modem
must
be
ready
to act
on
the
Courier's
RDL request. USRobotics
high
speed
modems
should
be
set to
&T4.
If
they
do
not
have
&T
testing capability,
they
should
be
set
to S16=8.
Initiating Modem
1.
If
DIP
switch
9 is OFF,
set
it
ON
so
that
it
does
not
hang
up
on
receipt of the +++ escape code. Issue
an
ATZ
command
to initiate
the
new
switch setting.
2.
Set the software to 2400
or
1200 bps.
The
CCITT-specified
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RDL signals
are
defined
only
for connections
at
2400
or
1200 -
bps.
3.
Disable
error
control
by
setting the
modem
to
&MO.
Then
establish a connection
with
the
remote
modem.
4.
Bring
the
modem
back to
Command
mode
by
sending
it
the
escape code:
one
second of
no
data,
three
pluses(+++),
and
another
second of
no
data.
5.
When
the
OK
result
code
appears,
send
the
modem
the
following
command.
ATS16=8 0
The
modem
enters RDL
mode
(S16=8),
the
MR
status
light
flashes,
and
the
modem
goes
back
online
(0
command).
Then
it
transmits
the
CCITT-defined RDL signals,
causing
the
remote
modem
to
enter
RDL mode.
6.
Type
any
data
at
the
keyboard. (Or
send
the
test pattern.)
7.
To
end
the test,
send
the
modem
the+++
escape
code
again
to
bring
it
back
to
Command
mode.
F-10 Modem Testing
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