Vector VN8912 Handbuch PDF herunterladen (Seite 43)

Vector Product Manual

The loopback testing facility in the Vector can aid in troubleshooting

ancillary data connections. It is often difficult to find a fault in a problem

like this, since the trouble could be at either end of the link. By loopback

testing the ancillary data channel on each end, at least you can easily find

which end has the trouble. To loopback test ancillary data:

1) Connect a computer serial port to the Vector.

2) Run a program on the computer with basic serial communications

functions, such as Procomm, Windows Terminal, or Win95 Hyperterminal.

3) Set the communications parameters as follows:

300 baud

8 bits

no parity

1 stop bit

echo off (half-duplex mode in Hyperterminal)

4) Make sure the software has the serial port chosen which is connected to

the Vector.

5) Verfiy that your Vector has been set to Voice Mode.

6) Type some characters on your computer, and verify that you do NOT

see them on your screen.

7) Go into the test menu on the Vector (see page 31), and select a

loopback rate of 16.8 kb/s or higher. The R

EADY light should come on.

8) Type on your computer keyboard. You should see your characters

echoed back to you on the screen.

If this test is successful, you have sent data down the cable to the Vector,

into the encoder, looped through to the decoder, and back to your

computer screen.

If not successful, try the following:

1) Type AT (Enter). If you get a response OK then you are probably

talking to a modem inside your computer, configured for the chosen com

setting. Try a different configuration.

2) Try a different com port. Sometimes these ports burn out if connected

wrong previously.

3) Remove any adapters, dongles or other connectors on the port.

4) Make sure you are using a straight through 9 pin to 9 pin cable. Do

not use a null modem cable.

ROUBLESHOOTING THE

ANCILLARY DATA CHANNEL

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Vector VN8912 Handbuch Seite 43