Chapter 3 - AT Commands
3.6
Modem Response (Result Code) Commands
The MT2834MR6’s modems can give responses to commands. The most common one is OK, but the modems also can alert you or your software to dial tones, busy signals, connection speeds, and whether the connection is made with error correction or compression enabled. These responses are called result codes, and they can be terse or verbose, Multi-Tech or standard, basic or extended.
En
Qn
&Qn
Echo Command Mode Characters n = 0 or 1
Default: E1
Normally, when you type commands on the keyboard, the modem echoes the characters back to the computer or terminal, which displays them on the monitor. Use the E command to turn this feature off and on.
E0 disables the echo.
E1 enables the echo.
Result Codes Enable/Disable n = 0, 1, or 2
Default: Q0
You can use the Q command to enable or disable result codes for applications such as computer-controlled autodialing. You can also use it to disable responses and echo in answer mode while leaving originate mode still intelligent; this is called the no response answer mode of operation.
Q0 (or Q) enables result codes.
Q1 disables result codes for applications such as computer-controlled auto-dialing.
Q2 enables the no response answer mode, which leaves originate mode intelligent while turning off answer mode responses and echo.
Result Codes (Multi-Tech or Standard AT) n = 0 or 1
Default: &Q0
The MT2834MR6 gives you a choice between Multi-Tech result codes and standard AT command set responses. Multi-Tech result codes give you more information, but some datacomm programs may not be able to use them, in which case, select the standard result codes.
&Q0 selects Multi-Tech responses with RELIABLE, LAPM, and COMPRESSED modifiers.
With &Q0, the verbose result code for 14,400 bps is CONNECT 14400 LAPM
COMPRESSED.
&Q1 selects AT responses with no RELIABLE, LAPM, or COMPRESSED modifiers. With
&Q1, the verbose result code for 14,400 bps is CONNECT 14400.
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Vn
Xn
&An
Chapter 1 - Introduction
Result Codes (Verbose/Terse) n = 0 or 1
Default: V1
The V command controls whether the modem’s result codes display as verbal (“verbose”) or digital (“terse”) messages. For example, if no carrier signal is detected after dialing, the result can be displayed either as NO CARRIER, or as the digit 3.
V0 (or V) displays the modem’s result codes as digits.
V1 displays result codes as words.
Result Codes and Call Progress Selection n = 0–4
Default: X0
The X command selects which result codes the modem provides in command mode and whether the modem uses “smart dialing” or “blind dialing”. When it smart dials, the modem listens for dial tones and busy signals and responds to them. When it blind dials, the modem ignores the signals and relies on timing instead.
X0 causes the modem to blind dial. Instead of looking for a dial tone, it pauses for the time set in register S6 and then dials regardless. Once a connection has been made, it sends the Bell 103 basic code CONNECT to the terminal. It ignores any busy signals.
X1 causes the modem to blind dial, but in addition to the basic CONNECT code it provides extended codes consisting of the word CONNECT and the speed of the connection:
CONNECT 2400, CONNECT 4800, CONNECT 9600, CONNECT 14400, CONNECT 19200,
CONNECT 28800, and so forth. In this mode, the modem does not recognize or respond to dial tones or busy signals.
X2 causes the modem to wait for a dial tone before dialing. If it does not detect a dial tone within the time set by S6, the modem sends a NO DIALTONE result code to the terminal. In this mode, the modem provides extended result codes, but does not respond to busy signals.
X3 causes the modem to blind dial, but also it looks for a busy signal, and if it detects one, it sends a BUSY result code to the terminal. In this mode, the modem provides extended result codes, but it does not respond to dial tones.
X4 causes the modem to look for a dial tone and a busy signal, and respond with NO
DIALTONE or BUSY, as appropriate. It also provides extended result codes. It is the most useful setting for most datacomm programs.
Answerback n = 0 or 1
Default: &A0
The &A command controls the MT2834MR6’s answerback feature. Answerbacks are used in some online realty applications and elsewhere as a security measure. The &A command enables a modem to return a message to an identification request from another computer.
The default identification is MESSAGE NOT PROGRAMMED.
&A0 disables the answerback feature.
&A1 enables the modem to return a message to an inquiry.
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