MultiModemII User Guide
94
2. Dial the remote modem and establish your online connection.
3. Type the escape sequence +++AT and press E
NTER
to bring your modem into
online command mode.
4. Type AT&T3 and press E
NTER
. Once you receive an OK message from your mo-
dem (if responses are enabled), your modem is placed in digital loopback mode.
5. Have someone enter data from the remote keyboard. For this test, typing multiple
uppercase U characters is a good way to send an alternating test pattern of binary
ones and zeros. The data received by your modem enters its analog receiver, is
converted to digital data, is reconverted into analog, and then is transmitted
back to the remote modem. Your modem passes this test if the data received on
the remote monitor is the same as the data entered from the remote keyboard.
6. To exit the test, turn off the modems.
Note:
You can also start and stop a local digital loopback test by using the front panel
LCD and buttons. See “Diagnostic Options Trunk” in Chapter 3.
Back-to-Back Test
This test verifies proper operation by connecting two MT5600BLs back to back using
an RJ-11 cable. By using an MT5600BL that is known to be good, you can test a second
MT5600BL that is suspect.
Computer or Terminal
Digital
Analog
Local MultiModem
MultiModem under test
Digital
Analog
UUUUUUUUUUU
UUU
Jumper
RJ-11 cable
Figure C-4. Back-to-back test.
1. Connect two MT5600BLs by plugging an RJ-11 cable into their LEASED jacks.
2. Set the terminal and modems to the same serial port speed. For instance, if you
are using a terminal that is limited to 9600 bps, set the modems to 9600 bps by
sending the command AT$SB9600&W0 to each modem.
3. Following the instructions in Chapter 7, set both modems to two-wire leased-
line mode. One should be set as the originate modem and the other as the an-
swer modem, but it does not matter which is which.
4. Turn on both units and wait for carrier detect (CD).
5. On the modem under test, short pins 2 and 3 of the RS-232C connector with a
paper clip or other metal device.
Summary of Contents for MT5600BA
Page 1: ...Model MT5600BA Model MT5600BL Data Fax Modem User Guide...
Page 7: ...Contents vii Appendix G ASCII Character Map 106 Index 107...
Page 8: ...MultiModemII User Guide viii...
Page 9: ...1 Introduction...
Page 13: ...2 Quick Start...
Page 24: ...MultiModemII User Guide 16...
Page 25: ...3 Using the Front Panel...
Page 28: ...MultiModemII User Guide 20 Trunks Limbs Branches Twigs Menu Overview...
Page 39: ...4 AT Commands S Registers Result Codes...
Page 64: ...MultiModemII User Guide 56...
Page 65: ...5 Remote Configuration...
Page 68: ...MultiModemII User Guide 60...
Page 69: ...6 Callback Security...
Page 76: ...MultiModemII User Guide 68...
Page 77: ...7 Leased Line Operation...
Page 82: ...MultiModemII User Guide 74...
Page 83: ...8 Solving Problems...
Page 91: ...Appendixes...
Page 115: ...Index...