Total Control MP/16, Operator'S Manual

Page: 152 / 182

E-2 Modem Testing
Analog Loopback
 
&T1, &T8
This test checks the operation of the modem's transmit ter and
receiver. Data flow is shown in Figure E-1.
Figure E-1. Data Flow During Analog Loopback
There are two analog loop back options. The first, &T1, involves
your typing data that you can verify at your screen.
The second option, &T8, is an internal self-test that does not
involve the keyboard or screen. It isolates the modem from the
computer interface to give you a more specific result.
&T1
1 The modem must be in Command mode. If you wish, set
Register S18 as a test timer, as explained earlier.
2 Send the modem the following command:
AT &M0 &T1 <Enter>
The modem disables error control, enters analog loopback (AL)
mode, and sends a CONNECT message. The MR status light
flashes.
3 Type recognizable data so that you can verify it when it is
looped back to the screen.
4 End the test. If you set S18, the modem automati cally stops the
test at the timeout, exits AL mode and responds OK.
If you didn't set Register S18, wait one second and type +++ to
bring the modem back to Command mode. If DIP switch 9 is
OFF, the modem also hangs up and ends the test.
If DIP switch 9 is ON, type AT&T0 to end the test. Or send
either ATH or the command that resets the modem, ATZ. The
latter two commands end the test and hang up the modem.