1200 BPS Internal Modem (250-3510A)     Selftest       Faxback Doc. # 4931

RDL is an advanced test feature which allows one modem to request the remote
modem to "loopback" data sent to it.  The RDL feature allows you to make a
complete unattended test of the remote modem.  Your local modem sends the 
data over the phone lines to the remote modem.  The remote modem will then 
loopback whatever is sent, and you should see your test message appear on 
your screen exactly as you sent it.

This test must be performed when the modems are on line.  To begin the test,
you must enter the command mode, using the +++ escape code.  Once on line 
and in command mode, you can tell the modem to begin the test.

1)  In command mode, enter:

    ATO2<CR>

    This test is now underway.  The message CONNECT followed by OK will be
    displayed.  Note that a result code of ERROR indicates that the remote
    modem is not capable of responding to RDL or has not been conditioned
    to do so.

2)  Enter a test message:

    How now brown cow.

3)  Check to see whether your test message is appearing on the screen exact-
    ly as you entered it.

4)  To end the test, enter:

    +++

5)  Modem should respond:

    OK
    You are now in command mode.

6)  Enter:

    ATO1<CR>

7)  Modem responds:

    CONNECT
    The test is ended

Notes:

1)  RDL is automatically terminated when the connection is discontinued.

2)  If the line is disconnected during RDL (the phone line is pulled out of
    the wall, etc.), the requesting modem will reset.  This prevents an
    unexpected request for RDL during the next call.

3)  Your modem will always respond to RDL when on-line.  The modem will
    respond to and initiate RDL; it does not matter which modem placed the
    original call.

4)  Note that the O0 command returns you to your previous state.  So if you
    enter ATO0<CR> once you have initiated RDL, the command will NOT exit 
    the RDL mode when returning on line.  To exit RDL and return on line, 
    you MUST enter ATO1<CR>.

If your modem has echoed back the test message exactly as you sent it, your
modem, the remote modem, the local data terminal equipment and the phone
lines all check out.

If there is a problem:

If the test message does not echo back correctly, either your modem, the
remote modem, the data equipment or the phone lines are at fault.  If you
have already successfully performed the local analog loopback test, you know
that your modem and computer are communicating properly.  If there is a
remote operator, he or she may wish to perform a local analog loopback test
as well to verify that the remote modem and computer are communicating.

Assuming that both the local and remote modems have successfully performed
local analog loopback test:

1)  Can you hear your modem dialing?

2)  If the modems are connecting but the test message is not coming through,
    you may have a problem with the phone lines.  Disconnect and try again.

(css 07/28/93)