Back-To-Back Test - Multitech BL-Series User Manual

MultiModemBL User Guide
8.5

Back-to-Back Test

This test lets you connect two MultiModems with an RJ-11 cable to verify proper operation. Using a
modem that is known to be operational, you can test a second modem that is suspect.
1. Plug the modular ends of an RJ-11 cable into both MultiModem's LEASE jack connectors.
2. Force DTR ON in both local and remote modems (Switch #1 DOWN).
3. Enter the command AT$SB9600$BA0&W0<CR> on both local and remote modems. This sets
the serial speed to 9600bps. Make sure that the terminal/computer is set for 9600 bps.
4. Set both modems in Leased-Line mode (DIP-Switch # 10 DOWN).
5. Set one modem to Answer enabled (DIP-Switch #5 UP) and the other modem to Originate
enabled (DIP-Switch #5 DOWN). Note it does not matter which modem (local/remote) is set to
Answer/Originate—just so they are set opposite.
6. Set DIP-Switch # 3 UP on both local and remote modems. This changes the transmit level to
-15dB and this change is necessary to operate in back-to-back mode
7. Turn on both units and wait for carrier detect (CD).
8. Short out pins 2 and 3 on the RS-232C interface on the remote modem (i.e.., with a paper clip or
some other metal device).
9. Entered characters should echo back to the sending modem.
102
PHONE PSTN LEASE EIA RS232C
VOLUME
PHONE PSTN LEASE EIA RS232C
VOLUME
Figure 8-4A. Back-to-Back Test Cabling
Figure 8-4B. Back-to-Back Testing
ON
OFF
POWER
ON
OFF
POWER