Appendix F - MMH2834 Modem Commands
F.2 Dialing Action Commands
Dial Command | D |
The letter D in a command causes the MMH2834 to dial the telephone number immediately following it. For example, if you enter ATD5551212 and hit RETURN, the MMH2834 dials the number
The MMH2834 gives you several choices of dialing methods. You can use tone or pulse dialing, by inserting a letter T or a P in the command string. (See section F.3 on Dial Modifiers).
You can also configure the modem to either wait for and detect dial tones and busy signals
(which we call
Note: There is another method of dialing, called “DTR Dialing”, where by manipulating the DTR signal on pin 20 of the RS232C/V.24 interface, a number stored in the modem's memory is automatically dialed. See section on DTR Dialing ($D command) for details.
Continuous Redial | A: or : |
If you select the
This command would be used only if you had already reached a busy number after executing a normal dial command. You simply enter A: (you need not enter AT, nor do you need to hit RETURN), and the modem will redial the number for you. If you again reach a busy signal, it redials again and again until it no longer detects a busy signaF. You can stop the MMH2834 from redialing by pressing any key.
Another method used to cause the modem to redial a phone number continuously is to enter a colon : at the end of the phone number. The result is the same as if you had entered A: after personally observing that the number was busy on the first dialing attempt. Using the colon in the dialing string is a step saver.
Dialing a Stored Number N
A telephone number that you have stored in the MMH2834’s number memory may be automatically dialed by entering ATNn where n = 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9. For example, a number stored at N3 would be dialed by entering ATN3 and RETURN. Do not include the letter D in this command, or the stored number will be erased (also see section F.4, Phone Number Memory Commands).
DTR Dialing | $D |
An alternate method of causing the MMH2834 to automatically dial is DTR Dialing. Data Terminal Ready (DTR) is a signal that comes into the modem from the terminal or computer to whichit is connected, on pin 20 of the RS232C interface. In DTR dialing, the modem automatically dials a stored number as soon as it receives a high DTR signal. The DTR dialing method is popular in synchronous applications.
To activate DTR Dialing, enter AT$D1 and hit RETURN. The modem dials the phone number stored in the N0 location of memory when it receives a high DTR signal. DTR must remain high for the duration of the call, until disconnect. To deactivate DTR dialing, enter AT$D0 and hit
RETURN.
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