Multitech MT1432BA, MT2834BAI manual Digital Loopback Test Remote/Automatic Synchronous Mode

Chapter 8 - Modem Testing

8.9Digital Loopback Test (Remote/Automatic) (Synchronous Mode)

This test must be run when you have a data connection with another modem. In this test, data is passed to the remote modem and is looped back to the local modem (as if an ATU2 command was issued in Asynchronous test mode), as shown in Figure 8-7. This lets you test the local and remote modem’s transmit and receive circuits, as well as your computer’s serial COM port and the phone lines. If the test results in a mismatch of entered/received data (multiple upper case “U” characters in Figure 8-6), the Local Analog Loopback Test should be performed on both the remote and local modems. If that test is successful, the problem may be the phone lines.

First make certain that you are set up for Synchronous operation by placing DIP-Switch #12 in the UP position. To initiate the Digital Loopback Test (remote/automatic), DIP-Switch #9 must be in the DOWN position, and the Answer/Originate switch (front of the modem) must be toggled to the UP position. Once you receive an OK message from your modem (if responses are enabled), the local modem is placed in Digital Loopback mode. To exit the Digital Loopback Test (remote/automatic), toggle the front panel Answ/Orig switch to the Answer position.

UUUUU

UUUUU

Digital Analog Analog Digital

Computer or Terminal Local MultiModem	Remote MultiModem Computer or Terminal
DIP-Switch #9
UP; Answ/Orig
Switch Toggled to
Answ position
when On-line

Figure 8-7. Synchronous Mode Digital Loopback Test (remote/automatic)

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