Multi-Tech Systems MT2834MR6 specification

Chapter 3 - AT Commands

&CDn	Cleardown at Disconnect
	n = 0 or 1
	Default: &CD0
	In the V.32, V.32bis, and V.34 protocols, a cleardown is sent by one of the modems to
	signal the other modem that it is going to hang up. A cleardown is rate renegotiation in
	which the modem that is hanging up tells the other modem that it has no speeds that it can
	connect at. It is designed to help the remote modem detect a hangup. However, it does take
	a second or two to send the cleardown. If you find this delay unacceptable, you can disable
	cleardown by using the &CD command.
	&CD0 enables cleardown at disconnect.
	&CD1 disables cleardown at disconnect.
>DTn	DTMF Detection
	n = 0 or 1
	Default: >DT0
	Normally, when it goes off-hook, a fax modem ignores tones from the other end of the
	connection unless they are fax or modem handshake tones, in which case it responds in
	kind. The >DT1 command causes the modem to report DTMF (touch-tone) tones and fax
	calling tones to software for further processing. A typical use would be for a program that
	routes calls to specific communications applications depending on the type of call or upon a
	DTMF tone added to a dialing string.
	>DT0 disables DTMF detection.
	>DT1 enables DTMF detection when the modem goes off-hook.
#Fn	Fallback Modes
	n = 0, 1, or 2
	Default: #F2
	The #F command controls whether the modem will fall back to a lower speed because of an
	unacceptable error rate. If line conditions deteriorate, the modem has the ability to fall back
	from its original speed to the next lower speed when operating in V.34, V.32terbo, V.32bis,
	or V.32 mode. If the error rate becomes too great, the modem performs a retrain at the next
	lower speed. If, after the retrain, the error rate is still too high, the modem performs a retrain
	at the next lower speed, down to 4800 bps.
	If the modem returns online at the original speed after the first retrain, the modem starts a
	counter and a timer. If three retrains occur within a two-minute period, the modem falls back
	to 4800 bps.
	The fallback and fall-forward speeds for the modem are 33.6K, 31.2K, 28.8K, 26.4K, 24.0K,
	21.6K, 19.2K, 16.8K, 14.4K, 12K, 9.6K, and 4.8K bps.
	#F0 (or #F) disables fallback when online.
	#F1 lets the modem fall back from the starting speed to a low speed of 4800 bps in 2400
	bps decrements.
	#F2 lets the modem fall back when line conditions deteriorate, but also lets it fall forward in
	2400 bps increments if line conditions improve.

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Multi-Tech Systems MT2834MR6 manual CDn Cleardown at Disconnect = 0 or Default &CD0, DTn Dtmf Detection = 0 or Default DT0

Contents

User Guide Trademarks Revision Date Description Contents Registers Warranty & Service Index 116 Introduction Manual Organization Introduction Description FCC Regulations for Telephone Line Interconnection FCC Fax Update Canadian Limitations Notice Technical Specifications Bell 103/113 Diagnostics300 bps Fax Carrier Power Supply Busy Switch Modem LED IndicatorsSpeed Data Rate bps LED State Safety Warnings 10 MT2834MR6 Installation Notes Dialing and Answering Dial-Up Handshaking Details Dial-Up Automatic Answering Call Termination AT Commands Modes of Operation Working with AT Commands Command Editing Command Structure AT Commands Flow control disabled Baud adjustModem baud rate Serial port baud rate Alternate out-of-band escape sequence Force answer modeEscape sequence selection Go back online Default none Dialing CommandsDial = phone number Default P Dial Modifier CommandsDefault R0 Pulse or Tone Dialing Or 4 through 255 seconds International models ATDT1028806127853500 $123456789 NdNe Number Linking = 0 or = 1 or Default none Phone Number Memory Commands P9,T14089876543 T14082345678 Default &W1 Configuration Storage and Recall CommandsDefault &F8 = 0, 8, or ATZ AT&W1 defaultAT&F8&W0 AT&F9&W0 Modem Response Result Code Commands Default &A0 DefaultResult Codes and Call Progress Selection #An Auto Speed Detection Default #A0 Online Connection CommandsDefault B0 DCn AT Command Control = 0 or Default %DC0 DTn Dtmf Detection = 0 or Default DT0 CDn Cleardown at Disconnect = 0 or Default &CD0#Fn Fallback Modes = 0, 1, or Default #F2 Default *H0 Default &G0 models outside U.KDefault &P0 Models outside U.K G2 U.K. models only #T1 enables TCM #T0 disables TCMDefault Y0 Issued V.34 Commands Default &C1 RS-232 Interface CommandsDefault &D2 Default &R1 Go high again Default &S1S0 forces DSR high S1 allows DSR to act normally, that is, to follow CD Default &E1 Error Correction and Data Compression CommandsDefault &E15 #Ln Error Correction Modes Default #L0 $An Autoreliable Buffering = 0 or Default $A0 $En Error Correction at 300 bps = 0 or Default $E0$Rn Retransmit Count = 0 or Default $R0 Speed Conversion Commands $SB300 $SBn Serial Port Baud Rate = speed Default $SB57600$SB1200 $SB2400 Immediate Action Commands Rate Renegotiation BSn Maximum Reliable Block Size = 0 or Default &BS1 Flow Control Commands$EBn Asynchronous Word Length = 0 or Default $EB0 Flow Control Disable Default &E8 Default &E6Non-Error Correction Mode Flow Control Default &E10 #Xn Number of Xoff Characters Sent = 0 or Default #X0 Default &E13Pacing Computer-Initiated Flow Control = 12 or Escape Sequences Atcr Remote Configuration Escape Sequence Remote Configuration Commands Line Probe Commands Diagnostic Commands Registers Registers Default 10 J Default 13 MDefault 8 H Return Character Default 45 North America and International Time for Carrier Abort TimerUnit 1 second Range 1-255 U.S.A Maximum S11 value is 255 ms 255 units Registers Registers Examples of Assigning Values Reading and Assigning S-Register ValuesExamples of Reading Values AT Commands Affecting S-Registers Error Correction, Data Compression & Speed Conversion Error Correction, Data Compression, and Speed Conversion How V.42 Detects and Corrects Errors MNP Classes Data Compression 1 #L0 Command V.42 Mode Select Command #L2 #L1 Command 3 #L2 Command Reliable Mode &E2 Non-Error Correction Mode &E0Autoreliable Mode &E1 Modes of Operation Flow control and pacing Flow Control 1 XON/XOFF Flow Control &E5 Modem-Initiated Flow ControlHardware Flow Control &E4 Pacing &E13 Non-Error Correction Mode Flow Control &E10 and &E111 XON/XOFF Pass-Through &E7 Hewlett Packard ENQ/ACK Pacing &E9 Non-Error Correction Mode Flow Control 10.1 V.42 Error Correction ModesModem-Initiated Flow Control 10.3 XON/XOFF Pass-Through LAP-M Error Correction MNP Error CorrectionResult Codes Speed Conversion Modem Baud Rate $MB Baud Adjust $BA Serial Port Baud Rate $SB Autoreliable Buffering $A Related CommandsMaximum Block Size &BS Autoreliable Fallback Character $F Summary 13.5 V.42 Error Correction at 300 bps $ERetransmit Count $R Testing & Troubleshooting Testing and Troubleshooting Local Analog Loopback Test V.54 Loop Test Procedure Remote digital loopback test Remote Digital Loopback Test V.54 Loop Local digital loopback test Local Digital Loopback Test V.54 Loop Warranty & Service Warranty Multi-Tech Systems, Inc. Warranty & Repairs Policies2 U.S. and Canadian Customers International Distributors International Customers outside U.S.A. and Canada Repair Procedures for International Customers Repair Procedures for U.S. and Canadian CustomersRepairs Internet Site Technical SupportCountry Telephone Appendices Appendix a Ascii Conversion Chart Dial Pulses Appendix B Figure B-2. Standard Dtmf frequencies Tone Dial Frequencies Result Code Summary Appendix C Standard AT Result Codes &Q1 Appendix D Register Unit Range Default DescriptionRegister Summary S34 Command Values Description AT Command SummaryAppendix E CDn 100 101 102 103 104 105 Signal Information Negative Positive RS-232C Interface SpecificationsAppendix F Transmitted Data TD Pin 2 To modem Functional Description of the RS-232C Signals Test Voltage +V Pin From modem External Transmit Clock XTC Pin To modem Appendix G Cable and Connector Diagrams Introduction to MultiTech Escape Methods Appendix H Escape Method 1 +++ATCR How to Select an Escape Method Aborting an Escape Sequence Registers and Escape Sequence Basic Procedure Introduction to Remote ConfigurationSetup Changing the Remote Escape Character Changing the Passwords Index Index 118 119 120 121 122 S000326A