Digital Security Controls PC1575 Manual de instalación descargar pdf (Pagina 103)

Appendix G: Modem Troubleshooting

This section lists many of the common problems people have when trying to get their

modems to work, and provides detailed information on how to solve them. Generally,

most modem problems are easy to fix, although they may not be immediately

recognizable.

1 Check Modem DIP Switch Settings (1200 baud modems only). This is the most

common source of communication errors. When you first get your modem, the

factory DIP switch settings may be different than those required by the DLS-1

software. The most common one set wrong is the DTR (Data Terminal Ready)

Status switch (on most modems this is SW 1, but check your modem manual). This

switch must be set to “Follow DTR” or in other words, support the use of the DTR

signal. Please refer to Appendix D for a list of the DIP switch settings for all DSC

supported modems. If you do not have one of the DSC approved modems, you

may attempt to set your modem according to the specifications listed in Appendix

2 Check Modem Specifications. Although most Hayes compatible modems claim

to be 100% compatible, many are not. The common specification left out of many

Hayes compatible modems is that they do not support the Bell 103 Simplex Mode

110 Baud Standard; in other words, they will not communicate at 110 baud. The

reason for this is that 110 baud is not a common transmission speed, whereas

1200 and 2400 baud are quite common. As a reference, check the modem manual

or even the modem box packaging. If you still are not sure, contact the

manufacturer of your modem.

3 Cancel Call Waiting. When Call Waiting is enabled, and another call comes in

when you are already connected, the connection is briefly cutoff, and then a high

beep tone is generated. The problem with this is that the modem will interpret this

as a loss of carrier and immediately hang-up. This will happen if the second call

comes in on either the panel end, or the computer end of the connection. Most

areas that provide call waiting service, have a means to disable it by pressing a

sequence of keys on your phone. To cancel Call Waiting, dial 70# or

∗

70 on a

touch-tone phone. Incoming callers will then hear a busy signal, and your

communication will not be interrupted.

4 Check Cable Connections. This is one of the most common problems that people

have when trying to get the modem to work. If the modem is an external one, then

make sure you have plugged the modem cable into the correct serial port (if you

have more than one). Also make sure the phone line is plugged into the proper wall

jack and the correct modem jack. Some modems provide an extra jack in which

to plug in a voice telephone; this jack is usually marked “To Phone”, but is

sometimes unmarked. If you plug the line and/or phone into the wrong modem

jack in some modems this will prevent proper operation of the modem.

5 Check For Dial Tone. If you are having problems dialling out or receiving calls,

then it is possible that the phone is not properly connected to the wall jack you are

using. The easiest way to test for this is to plug a regular telephone directly into

the jack, lift the receiver and listen for the dial tone. If you do not hear a dial tone,

then you know the phone line is broken at some point. Call your telephone

company to repair such a problem.

6 Check Computer Hardware . If you have an EXTERNAL modem, check to make

sure you have an external serial port that you can plug the modem cable into. Many

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