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MD1276A
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User Manual
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Black Box MD1276A User Manual

FEBRUARY 2004
0049-2200-001 Rev. A
0049-2200-500
MD1276A Global 56K/V90 Modem
User’s Guide
Contents
Unpacking Your Hardware................................................................................................. 7
Additional Items You Need.................................................................................................. 7
Hardware Overview .......................................................................................................... 8
Installation Summary........................................................................................................... 9
Connecting the Cables ..................................................................................................... 10
Driver Installation...............................................................................................................11
Modem LED Display .......................................................................................................... 12
Front Panel Mode LEDs .................................................................................................... 13
The AT Commands............................................................................................................ 14
Selecting Speeds.............................................................................................................. 20
Flow Control..................................................................................................................... 24
Configuring the Modem..................................................................................................... 26
Error Correction ...................................................................................................................... 27
Error Correction Protocols................................................................................................ 27
Security & Encryption ............................................................................................................. 32
Encryption ........................................................................................................................ 39
Synchronous Modes .............................................................................................................. 47
Leased Line Operations ................................................................................................... 51
Dumb Mode Operation ............................................................................................................ 54
The Option Switches........................................................................................................ 60
V.25bis Operations ................................................................................................................. 61
Distinctive Ring....................................................................................................................... 69
Caller ID .................................................................................................................................. 70
Call Logging ...................................................................................................................... 73
Commands.............................................................................................................................. 74
+++ Escape Sequence ..................................................................................................... 74
**** Remote Access Sequence ........................................................................................ 75
AT? Interactive Command Help ......................................................................................... 77
A/ Repeat Last Command ................................................................................................. 78
ATA Answer ..................................................................................................................... 79
ATBn Select Communications Standard............................................................................ 80
ATD Dial............................................................................................................................ 84
Dial Modifiers.................................................................................................................... 85
ATE Echo.......................................................................................................................... 90
ATH Hang Up.................................................................................................................... 91
ATI Identity........................................................................................................................ 92
ATL Speaker Volume Control ............................................................................................ 93
ATM Monitor ..................................................................................................................... 94
ATO Return to On-line State ............................................................................................. 95
ATQ Quiet (Suppress Response Codes) ......................................................................... 97
ATR Set Terminal Speed ................................................................................................... 98
ATSn? Display S Register Value..................................................................................... 100
ATSn= Set S Register Value ........................................................................................... 101
ATV Verbal Response Codes ........................................................................................ 102
ATW Connection Speed Information ............................................................................... 103
ATX Extended Response Codes .................................................................................... 104
Page ii
ATZn Restore Configuration Profile ................................................................................ 106
AT&B Character Length ................................................................................................. 107
AT&C Controlling Data Carrier Detect ............................................................................. 108
AT&D Controlling Data Terminal Ready ........................................................................... 109
AT&F. Reinitialise Modem .................................................................................................110
AT&F Restore Factory Defaults ...................................................................................... 111
AT&G Guard Tone ...........................................................................................................112
AT&H Clock Control ......................................................................................................... 113
AT&K Flow Control .......................................................................................................... 114
AT&L Leased Line ...........................................................................................................116
AT&M Synchronous/Asynchronous Mode ...................................................................... 117
AT&N Abort Connection ...................................................................................................119
AT&R RTS/CTS Control................................................................................................... 120
AT&S Controlling DSR..................................................................................................... 121
AT&Vn View Active Configuration Profile ...................................................................... 122
AT&Wn Write Configuration Parameters......................................................................... 123
AT&X Transmit Clock...................................................................................................... 124
AT&Yn Select Stored Profile on Power Up ..................................................................... 125
AT&Z Stored Phone Number ........................................................................................... 126
AT#A Universal Remote Access..................................................................................... 127
AT#B 1200bps Originate Mode....................................................................................... 129
AT#C V.25 Calling Tones ................................................................................................ 130
AT#CID Caller ID.............................................................................................................. 131
AT#D V.25bis Direct Calling ............................................................................................ 133
AT#E Encryption ............................................................................................................. 134
AT#H Display Help.......................................................................................................... 135
AT#I V.22bis Leased Line............................................................................................... 136
AT#J V.42 Capability Checking ....................................................................................... 137
AT#K MNP 10 mode ........................................................................................................ 138
AT#M Command Mode Selection..................................................................................... 139
AT#N V.25bis Character Encoding ................................................................................. 140
AT#O Buffer Overflow................................................................................................... 141
AT#Q V.25bis Terminal Speed ........................................................................................ 142
AT#R Enable Remote Control.......................................................................................... 143
AT#S Security Menu....................................................................................................... 144
AT#U V.25bis Character Set .......................................................................................... 145
AT#V Verifier ................................................................................................................. 146
AT%B AutoAnswer Setting............................................................................................ 147
AT%C Compression Control ........................................................................................... 148
AT%D Set Disconnect Delay .......................................................................................... 149
AT%E Auto EQM Retrain................................................................................................. 150
AT%F DTR/DSR override................................................................................................ 151
AT%H MNP 10 Negotiation Speed................................................................................... 152
AT%K CTS During Dial and Handshake .......................................................................... 153
AT%L Display Line Signal Level ..................................................................................... 154
AT%Ln Transmit Level (Data Mode) ............................................................................... 155
AT%M Mode LED Indication............................................................................................ 156
AT%N Non-Standard Terminal Speeds............................................................................ 157
AT%P CONNECT Message Timing .................................................................................. 158
AT%Q Line Signal Quality............................................................................................... 159
AT%R CTS Override....................................................................................................... 160
AT%S DSR Override ...................................................................................................... 161
AT%T DCD Override....................................................................................................... 162
Page iii
AT%U V.42 Response Codes ........................................................................................ 163
AT%W Welcome Message ............................................................................................. 164
AT\A MNP Block Size ...................................................................................................... 165
AT\Bn Generate Break ................................................................................................... 166
AT\J Auto-Reliable Fallback ............................................................................................ 167
AT\K Break Control......................................................................................................... 168
AT\N Asynchronous Operating Mode ............................................................................. 170
AT\Q Extended Flow Control .......................................................................................... 172
AT\S Display Active Configuration .................................................................................. 173
AT\Tn Inactivity Timer (Data Mode)................................................................................. 174
AT\V Error Correction Response Codes ........................................................................ 175
AT\X XON/XOFF Pass Through ...................................................................................... 176
AT*K Select Primary DES KEY from Stored Keys ........................................................... 177
AT*R V.13 Remote RTS Signalling................................................................................... 178
AT*S Change Current User Password ........................................................................... 179
AT*T Auto Call Redial ...................................................................................................... 180
AT*V Maximum V.42bis Dictionary Size.......................................................................... 181
AT*W Welcome Message Text ....................................................................................... 182
AT*Y Escape Seq. Detection in Sync. ............................................................................ 183
AT+ICF Character Framing and Parity Select .................................................................. 184
AT+MS Select Modulation ............................................................................................... 185
AT+MS=? Reporting Supports Options........................................................................... 189
AT-Q MNP10 Fallback to V.22bis..................................................................................... 190
AT-DATE Time & Date ..................................................................................................... 191
AT-LOG Call Log ............................................................................................................. 192
AT:E V.32 compromise Equaliser .................................................................................... 193
V.25BIS - CIC Connect Incoming Call .............................................................................. 194
V.25BIS - CRN Dial.......................................................................................................... 195
V.25BIS - CRS Dial Stored Number ................................................................................. 197
V.25BIS - DIC Disregard Incoming Call ............................................................................ 198
V.25BIS - PRN Stored Phone Number ............................................................................. 199
V.25BIS - RST Reset ...................................................................................................... 200
S Registers ........................................................................................................................... 201
ATS0 Rings Before Answer........................................................................................... 203
ATS1 Ring Count ............................................................................................................ 204
ATS2 Escape Sequence Character................................................................................ 205
ATS3 Carriage Return Character.................................................................................... 206
ATS4 Line Feed Character ............................................................................................. 207
ATS5 Backspace Character ........................................................................................... 208
ATS6 Dial Tone Wait Time ............................................................................................... 209
ATS7 Wait for Carrier ..................................................................................................... 210
ATS8 Pause Dial Modifier Delay.......................................................................................211
ATS9 Carrier Detect Response Time.............................................................................. 212
ATS10 Lost Carrier/Hang Up Delay ................................................................................ 213
ATS11 DTMF Tone Timing ............................................................................................... 214
ATS12 Escape Sequence Guard Time ........................................................................... 215
ATS16 Test in Progress (read only) ............................................................................... 216
ATS18 Test Timer ........................................................................................................... 217
ATS25 DTR Loss Detection ............................................................................................ 218
ATS26 RTS/CTS Delay ................................................................................................... 219
ATS27 Delay Before Dial ................................................................................................ 220
ATS29 Hook Flash Duration............................................................................................ 221
ATS30 Inactivity Timer .................................................................................................... 222
Page iv
ATS33 EQM Threshold Value ......................................................................................... 224
ATS38 Disconnect Delay................................................................................................ 225
ATS42 Modem Disconnect Reason ................................................................................ 226
ATS43 Break Sequence Length ..................................................................................... 227
ATS45 V.22bis EQM Threshold Value ............................................................................. 228
ATS57 DTR High Detection ............................................................................................. 229
ATS62 V.42 Detection Timer........................................................................................... 230
ATS66 Remote Access Guard Time ............................................................................... 231
ATS67 Remote Access Character.................................................................................. 232
ATS69 Command Line Time-out ...................................................................................... 233
ATS71 Ignore Incoming Call ............................................................................................ 234
ATS74 Disconnect Reason for Prev. Call ....................................................................... 235
ATS80 Flow Control High Water Mark ............................................................................ 236
ATS81 Flow Control Low Water Mark ............................................................................ 237
ATS82 Failsafe Flow Control Overrun............................................................................ 238
ATS95 Extended Response Codes ................................................................................ 239
ATS96 Help Page Width .................................................................................................. 240
ATS97 Help Page Length................................................................................................ 241
ATS105 Voice ‘Dead Man’ Timer..................................................................................... 242
ATS122 AutoRateChange............................................................................................... 243
ATS123 AutoRateChange............................................................................................... 244
ATS124 Duration EQM.................................................................................................... 245
Modem Response Codes...................................................................................................... 246
RS-232 Signals..................................................................................................................... 248
Abbreviated Command List................................................................................................... 251
Glossary............................................................................................................................... 261
Specifications ....................................................................................................................... 282
FCC Requirements for Telephone-Line Equipment ................................................................ 284
Page v
Introduction
Welcome to the MD1276A Modem User Guide, a comprehensive guide to the efficient use of your modem. Together with the Read Me First Guide supplied with your modem, this reference manual provides all the information needed to make maximum use of your equipment and software. This User Guide is divided into the following sections:
Getting Started
o A complete description about how to get started using your equipment, including basic
details and more advanced topics.
Error Correction
o Examines and explains the error correction features, includingV.42bis data
compression, of your equipment.
Security
o Examines and explains the data security and encryption features of your equipment.
Synchronous Modes
o Full details on how to use your modem for synchronous operations.
Dumb Mode
o Provides product specified information on Dumb Mode operation.
V.25bis Operations
o Describes how your modem implements V.25bis and how it interacts with AT
commands.
Distinctive Ring
o Explains how to use Distinctive Ring and its associated commands.
Caller Id
o Explains how to use Caller Id and its associated commands.
AT Commands
o Provides a complete description of all commands available in your modem.
S Registers
o Introduces you to S Registers and how to use them. o Contains a description of the available S Registers.
Response Codes
o This section provides information on the response codes supported by your modem.
RS-232 Signals
o This section provides information on signals supported on the modem’s RS- 232 socket.
Abbreviated Command Listing
o This section provides a quick reference of the commands for the BLACK BOX MD1276A modem.
Glossary of Communications Terms
o Provides descriptions of modem, facsimile and other communications terms.
®
Page 6
Installation
Unpacking Your Hardware
Your package should include:
• The BLACK BOX® MD1276A modem
• An RJ-11 telephone-line cable
• A power supply module
• This User’s Guide
If your package contents are damaged or missing, please contact your place of purchase immediately.
Additional Items You Need
To use your mode, you need the following additional items:
• Two- or four-wire transmission line or leased line
• A power source that provides 85 to 265 Volts AC, 50 to 60 Hz, single phase
Installation
Page 7
Hardware Overview
Back View
The following figure shows the back view of the modem. Starting from the left side, this view shows:
• A line jack for connecting the modem to the communications line.
• An audio jack for leased-line operation.
• A female, 25-pin RS-232 connector for connecting a standard DTE (RTU).
• A power connector.
• An ON/OFF switch.
Telco/Dial Line
Telephone Set
DTE RS232 Connector
Low Voltage Power Input
ON/OFF
Front View
The front view of the modem has 10 LED status indicators. For more information about these indicators, see “Modem LED Display” on page 14 and “Front Panel Mode LEDs” on page 15.
Option DIP Switch (see page 62)
LEDs (see page 15)
Mode Switch for Dumb Operation (see page 56)
Data/Talk Switch (see page 58)
Page 8
Installation
Installation Summary
The modem installation involves the following steps:
1. Finding a suitable location for the modem. See the section below.
2. Making the necessary modem connections. See page 12.
3. Installing the modem driver. See page 13.
Finding a Suitable Location
The location you select for your modem should provide easy access to the back panel communications interfaces and provide a clear view of the front panel LED indicators.
Page 9
Connecting the Cables
1. Turn off your computer.
2. Plug the data cable's male end (pins showing) into the connector marked RS232 at the back
of your Modem and then plug the female end (no pins showing) of the same cable into the COM port at the back of your computer.
3. Your computer's COM port could be 9 pins or 25 pins. Use the appropriate connector on the cable suppled to conntect your Modem to your Serial port.
4. Plug the telephone cable into the connector marked LINE at the back of your Modem and the other end of the cable into your telephone wall socket.
+
Your Modem has a Telephone Set connector to allow 4-wire leased-line operation. Refer to the section on Leased Line Operations for details on this feature.
5. Plug the power cable pin into the POWER connector at the back of your Modem and plug the power supply into a suitable power point.
6. Use the ON/OFF switch to turn on your Modem. Then check that some of the Modem lights illuminate.
7. Restart your computer.
8. Now you need to install your Modem's Driver. Which operating system is your computer running? Read the next section for driver installation instructions.
Telco/Dial Line
Telephone Set
DTE RS232 Connector
Page 10
Low Voltage Power Input
ON/OFF
Installation
Driver Installation
Windows 2000
1. Windows will detect the modem automatically. Please insert the supplied CD and click "Next".
2. Select "Search for a suitable driver for my device [recommended]", and then click "Next".
3. Select "Specify a location" and click "Next".
4. Enter the driver location "D:\" where D:\ is the letter of your CD ROM drive and click on "OK".
5. Windows will find the correct driver for your modem. Click "Next" to continue.
6. When the "Digital Signature Not Found" screen appears, click "Yes" to continue.
7. Click "Finish" to end this procedure.
Windows ME
1. Please insert the supplied CD and, when the "Found New Hardware Wizard" recognises the new Modem, select "Specify the location of the driver [Advanced]" and click "Next" to search for the driver.
2. Select "Search for the best driver in these locations" and choose "Specify a location". Type in "D:\" (where D:\ is the letter of your CD ROM drive) and click "Next" to continue.
3. Click "Next" to start the installation.
4. Click "Finish" to end this installation procedure.
Windows 98
1. Please insert the driver CD supplied and, when the "Found New Hardware Wizard" recognises the new Modem, click Next to search for the driver.
2. Select the "Search for the best driver your device. [Recommended]" and click "Next" to continue.
3. Select the "Specify a location" option and type "D:\" where D:\ is the letter of your CD ROM drive. Click "Next" to start the search for your driver.
4. Click "Next" to start the installation.
5. Click "Finish".
Page 11
Modem LED Display
+
When your modem is using V.90, the Front Panel Mode LEDs will display the speed closest to the K56flex speed.
Transmit Data (TXD)
LED will flash when the modem is sending data.
Receive Data (RXD)
LED will flash when the modem is transferring data from the remote to the local computer.
Off-Hook
LED will glow when the modem is on-line; ie. dialling or answering
Carrier Detect
LED will glow when the modem detects a valid carrier signal from a remote modem.
Auto-Answer
LED will glow to indicate auto-answering operation. If the modem is performing a test, the LED will flash until the test is completed or cancelled.
Terminal Ready
LED indicates the ‘Data Terminal Ready’ (DTR) signal is asserted.
Page 12
Installation
Front Panel Mode LEDs
Line Modulation One Two Three Four
K56flex 56000 bps Z M Z M m m K56flex 54000 bps Z M Z M l m K56flex 52000 bps Z M m m m K56flex 50000 bps Z M l m m K56flex 48000 bps Z M m l m K56flex 46000 bps Z M l l m K56flex 44000 bps m m m m K56flex 42000 bps l m m m K56flex 40000 bps m l m m K56flex 38000 bps l l m m K56flex 36000 bps Z M Z M m m K56flex 34000 bps l m l m K56flex 32000 bps m l l m K56flex 30000 bps l l l m 33600 bps ZF ZF m l 31200 bps ZF ZF l l 28800 bps ZF m m l 26400 bps ZF m l l 24000 bps ZF l l l 21600 bps Z M m m l 19200 bps Z M l m l 16800 bps Z M m l l 14400 bps l l l l 12000 bps l l m l 9600 bps m l m l 7200 bps m l l l 4800 bps l m m l 2400 bps ZS m m l 1200 bps ZS m l l 1200/75 bps ZS l m l 300 bps ZS l l l Fax 14400 bps m ZS ZS l Fax 9600 bps m m ZS l Fax 7200 bps m l ZS l Fax 4800 bps l m ZS l Fax 2400 bps l l ZS l LED: l = Off m = On
Flashing:ZS = Slow, ZM = Med, ZF = Fast
Page 13
The AT Commands
The AT commands are a group of special commands recognised by your modem. These commands derive their name from the letters AT, which are used to prefix commands. Before continuing:
• Run your communications software and enter local mode (or terminal mode) at 38,400 bps Refer to your communication software manual for details.
The Attention Code
An AT (sometimes known as the ATtention code) usually precedes all commands being sent to the modem. It is used to gain the modem’s attention, informing it that you are about to send a command. For example:
• Type the command: ATI9 <E>
Your modem’s firmware identity message will appear on your computer screen. If you type I9 only, your modem will not respond. If you type AT19, your modem will report an ERROR.
You may enter the attention code in all upper case, or all lower case letters, such as: AT or at
Multiple Commands
You may place multiple modem commands after an AT provided the total number of characters does not exceed 80. For example, a valid command to display the modem’s firmware identity twice is:
• Type in the command: ATI9I9 <E>
An AT is not required in front of the second I9 command. You only need one attention code for each command line. To make this command more readable, you can add spaces between the two commands:
• Type in the command: AT I9 I9 <E>
The modem will execute the command as if the spaces are not there.
The Escape Sequence
When you issue commands to the modem all dialogue is occurring between your computer and the modem. This situation is known as local command state.
When you connect to a remote system, dialogue will be occurring between your computer and the remote system. This is known as on-line state. Because the modem assumes, after it enters on-line state, all the data you send it is to be sent on to the remote modem, it ignores any AT commands you give it while in on-line state.
To force the modem to return to local command state, enter an escapesequence. An escape sequence consists of a one second delay, three + characters typed rapidly and another one second delay. For example:
Page 14
AT Commands
• Type: AT&T1 <E> The modem will enter on-line state (this command actually causes the modem to enter test
mode, but is equivalent to entering on-line state). Now try to view the modem’s firmware identity code:
• Type: ATI9 <E> Your command will be ignored. This is because the modem assumes you are typing characters to
be sent to a remote system. Now enter an escape sequence. Do not type any characters for one second, type +++ rapidly
and wait another full second. The modem will respond with an OK message to indicate it has returned to local command state. You will be able to view the modem’s firmware identity.
Before continuing:
• Type: AT&T0 <E> This command is used to halt the test.
The Repeat Command
The repeat command is used to re-execute the last command issued to the modem. Issue the ATI9 command and the modem’s firmware identity code will be displayed on the screen.
• Type: A/ The identity code will appear again. You don’t have to enter AT before the repeat command. You also do not have to press the
ENTER key. This is the only modem command which does not require you to enter AT before it, and one of the few commands which does not require you to press the ENTER key. The A/ command is intended primarily for re-dialling a telephone number that was previously engaged.
The Help Command
Your modem will display information about the AT commands it supports if you type a question mark (?) in your AT command.
For example:
• Type: AT? <E> Your modem will display a list of all the commands it supports.
• Type: AT?DTR <E> Your modem will display a summary of commands involving DTR.
• Type: AT?\N3%C2&D2 <E> Your modem will display summaries of the \N, %C and &D commands.
Page 15
Response Codes
Your modem is capable of telling you, with on screen messages, what it is doing. These messages are known response codes or result codes, and you will see them from time to time.
For example: After a command is successfully executed, the response is: OK After a connection is established,
the response is: CONNECT A complete list of Response Codes can be found in Appendix A.
Dialling
The AT commands may be used to initiate dialling with the modem. Your modem does not require a telephone handset to be connected to it in order to dial.
The D (Dial) command is used to initiate a telephone call. The most basic form of the D command is:
ATD number where the number is the telephone number you are dialling. Having set your communications software for 38,400 bps operation:
• Type: ATD01234 <E>
Your modem will begin to dial.
+
If your modem receives a character from your computer while dialling is being performed, it will immediately hang up, send a NO CARRIER response message to the computer and return to local command state. After a few seconds the message CONNECT will appear on the screen.
If a NO CARRIER message appears, then your modem has not been able to make a connection. Check your communications software is set for 38,400 bps operation and your modem is correctly connected to your computer and the telephone line. You may use the A/ command to redial.
To hang up the modem, enter an escape sequence (+++). The modem will respond with an OK message.
• Type: ATH <E>
The modem will hang up.
+
Your computer must assert the DTR signal before dialling can start. Usually, this is done by your communications software. If the DTR signal is lowered at any stage of communications, after the &D2 command has been issued, the modem will hang up and return to local command state. Interpretation of the DTR signal may be changed with the &D command.
Page 16
AT Commands
Dial Modifiers
Dial modifiers are characters than can be included in a phone number to make the modem perform special tasks while dialling. For example, not all modem users will be using a dedicated telephone line. Some users will have their modems connected to PABXs. To allow users of PABXs to operate their modems successfully, dial modifiers are supported on the modem.
Most PABXs require you to dial 0 or 9 (in order to obtain an outside line) and wait for a dial tone before dialling the actual phone number. Using dial modifiers, you can successfully dial the phone number 12345 through a PABX using the command:
ATD0,12345
The , (comma) dial modifier causes the modem to pause for a short time after dialling 0. This allows most PABXs sufficient time to obtain a line before dialling.
The factory default delay for the , modifier is two seconds. You may change the length of this delay if necessary. Its length is determined by the value in S Register 8.
Another method of making the modem wait for a dial tone is to include the W dial modifier. The W modifier causes the modem to examine the phone line to ensure a dial tone has been applied before dialling starts:
ATD0W12345
If the modem cannot detect a dial tone within the time specified by S Register 7, the modem will return to local command state and send a NO DIALTONE message to the computer (if either the X2, X4, or X5 commands have been issued).
Due to differences with some older telephone exchanges, dial tone detection may not be possible with your modem. Your modem will only recognise dial tones between 200 Hz and 600 Hz.
If your telephone line supports tone dialling then a useful dial modifier is the T modifier. Inserting a T modifier before the number you are dialling causes the modem to tone dial that number. For example:
ATDT12345 This will cause the modem to dial the phone number 12345. These modifiers may be placed at any point in the number you are dialling and they may be
intermingled in the same number. More information about dial modifiers can be found in the Command Descriptions chapter of this guide.
Page 17
Hanging Up
The H command is used to hang up the modem. After you have finished communicating with another computer you must hang up your modem. Similarly, you must hang up the phone after calling another person. If you don’t, no one will be able to call you and you may even be charged for the length of time the phone was off the hook.
To hang up your modem:
• Type: ATH <E> The modem will return an OK response message.
Stored Number Dialling
Your modem has the ability to store phone numbers which may be dialed at a later time. This is similar to ‘abbreviated dialling’, which may be supported by your telephone.
To store a phone number use the &Z command. For example:
• Type: AT&Z1=012345 <E> The phone number 012345 will be stored as phone number one. The S dial modifier is used to
dial a phone number that has been stored in your modem:
• Type: ATDS=1 <E> The modem will dial stored phone number one.
+
Do not include an AT, D command, or S dial modifier in the stored phone number. If synchronous mode 2 is being used, the ; (semi-colon) dial modifier should not be included.
Answering Calls
As well as dialling other modems, your modem can answer calls made to it by other modems.
Page 18
AT Commands
Your modem is pre-configured to automatically answer any incoming call, provided it is switched on, is in local command state, DTR is high and is not performing a test. If you receive a call on the phone line the modem is connected to, it will answer the call and attempt to connect to the calling modem.
S Register 0 contains the number of rings the modem will wait before answering a call. If a value of 4 is placed in S Register 0, the modem will answer an incoming call immediately after the fourth ring. If a 0 value is placed in S Register 0, the modem will not answer an incoming call.
The communications standard used by the modem in its attempt to connect with a calling modem is determined by the B command.
If the phone does ring, and verbal response codes are selected (ATV1), the modem will issue RING messages until the number of rings stored in S Register 0 is reached. The modem will then go on line, transmit an answer tone, and attempt to connect to the calling modem using the communications standard selected by the B command.
By default the modem is set to B0. B0 is the auto range setting. This should connect to virtually all communications standards and normally you do not have to alter this. As soon as a connection is established, the modem will send a CONNECT message to your computer and enter on-line state in answer mode.
Page 19
Selecting Speeds
The following section describes how to select line and terminal speeds for your modem.
Terminal Speeds
Your modem has the ability to communicate with your computer at various speeds. The modem offers two speed modes: variable speed mode and constant speed mode.
Constant speed mode forces your modem to maintain the terminal speed that was selected when you dialed another modem, even if the connection speed made with the other modem does not match the terminal speed of your modem and computer.
For example, if your modem connected to another modem at 2400 bps and its terminal speed is 9600 bps, the modem will maintain its terminal speed at 9600 bps. Because of this, you must select flow control between the modem and your computer. To select constant speed mode:
• Type: AT\N0 <E> For more details on constant speed mode and flow controls, see the Command Descriptions
chapter for a discussion of the \N, B and &K commands. + Some computers cannot cope with receiving data at speeds above 19,200 bps. If you wish to run at high speeds, you should install a COM port that has a 16550 chip in place of your regular COM port. The 16550 chip allows your computer to accept data at very high speeds when used with suitable drivers and software.
Variable speed mode allows your modem to automatically adjust its terminal speed to match the line speed. For example, if your modem connects to another modem at 4800 bps and its terminal speed is 9600 bps, the modem will automatically change its terminal speed to 4800 bps (and, thus, you or your software would have to change the speed of your computer to 4800 bps).
If you have variable speed mode and B0, B1, B2 or B9 selected, the modem will attempt to connect at a speed to match the terminal speed.
At 300 bps, select B0 or B2 for V.21, or B1 for Bell 103. At 1200 bps, select B0 for V.23, B1 for Bell 212A, or B2 for V.22.
Variable speed mode may be selected by:
• Type: AT\N1 <E> For more details about the variable speed mode, see the \N and B commands in the Command
Descriptions chapter of this guide.
Page 20
AT Commands
Setting Terminal Speeds
Your modem can sense the terminal speed of the computer and automatically change its terminal speed to match. This is known as ‘auto bauding’, and is done each time an AT command is issued to the modem.
Your modem can auto baud at 300 bps through 9600 bps, 14,400 bps, 19,200 bps, 38,400 bps, 57,600 bps and 115,200 bps.
The R command may also be used to disable autobauding and lock the terminal speed. Refer to the R command for available speeds.
Line Speeds
Connection speeds higher than 33600bps can only be obtained by calling an Internet Service Provider (ISP) or Central Site which supports the Rockwell K56flex™ protocol. The speeds at which you will be able to connect also depend on the quality of the telephone line used when making the connection.
The B command determines the speed at which your modem connects to another modem. The listed B commands are provided by your modem.
In most cases you should select B0, as this setting attempts to connect at any speed supported by the modem.
V.90 & V.34 Typical Settings
Here are some example settings that may be relevant to the way in which you wish to operate your modem.
Example 1 - Dialling or answering other modems at the highest speed.
B Command Setting: B0 Terminal Speed: 115,200 bps Flow Control: On (&K3 for RTS/CTS flow control)
Use this arrangement when dialling online information services or bulletin boards. With these settings, you modem will attempt to connect at any speed from 56,000 bps to 1200 bps. These are the default settings of your modem.
If you wish your modem to answer incoming calls, use these settings. This will allow your modem to connect at any speed between 56,000 bps and 300 bps. If you are using a software program that controls the answering of your modem (as some bulletin board systems do) you may need to issue an ATS0=0 command to disable auto-answering, otherwise issue ATS0=2 to make the modem answer calls after two rings (the default setting).
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Example 2 - Dialling other modems at 19,200 bps (V.34 or V.FC)
B Command Setting: B18 Terminal Speed: 57,600 bps Flow Control: On (&K3 for RTS/CTS flow control)
You may use this arrangement when dialling online information services or bulletin boards. With these settings, you modem will attempt to connect at 19,200 bps, but may change the line speed if the quality of the telephone line does not support this speed.
Example 3 - Dialling information services at 1200 bps (or V.22)
B Command Setting: B6 Terminal Speed: 38400 bps Flow Control: On (&K3 for RTS/CTS flow control)
Some information services do not provide connections higher than 1200 bps; these settings allow you to connect to such services. Problems may also occur if error correction is switched on; if the information service does not support V.42 or MNP, issue the \N0 command before dialling.
V.32bis Modem Typical Settings
Here are some example settings that may be relevant to the way in which you wish to operate your modem with V.32bis.
Example 1 - Dialling other modems at the highest possible V.32bis speed
B Command Setting: B0 Terminal Speed: 38,400 bps Flow Control: On (&K3 for RTS/CTS flow control)
Use this arrangement when dialling online information services or bulletin boards. With these settings, your modem will attempt to connect at any speed from 14,400 bps to 1200 bps. These are the default settings of your modem.
Example 2 - Dialling other modems at 14,400 bps (or V.32bis)
B Command Setting: B15 Terminal Speed: 38,400 bps Flow Control: On (&K3 for RTS/CTS flow control)
You may use this arrangement when dialling online information services or bulletin boards. With these settings, your modem will attempt to connect at any speed from 14,400 bps to 1200 bps. Because V.32bis operation is not suitable on poor-quality telephone lines, we recommend you use these settings with caution; if you have trouble connecting to another modem using V.32bis, revert to the settings shown in Example 1.
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AT Commands
Example 3 - Answering incoming calls
B Command Setting: B9 Terminal Speed: 38,400 bps Flow Control: On (&K3 for RTS/CTS flow control)
If you wish your modem to answer incoming calls, use these settings. This will allow your modem to connect at any speed between 14,400 bps and 300 bps. If you are using a software program that controls the answering of your modem (as some bulletin board systems do) you may need to issue an ATS0=0 command to disable auto-answering, otherwise issue ATS0=2 to make the modem answer calls after two rings (the default setting).
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Flow Control
Your modem supports RTS/CTS, XON/XOFF and Transparent XON/OFF flow control. Flow control ensures that data is not lost between your computer and your modem. Flow control will be ignored when your modem is configured for variable speed mode (AT\N1) or is in local command state.
RTS/CTS Flow Control
RTS/CTS flow control takes place when the modem and computer manipulate the CTS (Clear To Send) and RTS (Request To Send) signals to stop and start data flow. This form of flow control is recommended if supported by your computer and communications software, as it does not interfere with file transfer protocols.
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In order for flow control to operate correctly between your computer and the modem, the appropriate form of flow control must be selected with your communications software. See your communications software manual for details. You must also have a modem cable that connects the RTS and CTS signals of your modem to your computer.
RTS/CTS flow control is selected with the &K3 command.
XON/XOFF Flow Control
XON/XOFF flow control takes place when the modem and communications software transmit XON and XOFF characters to start and stop data flow. This form of flow control is only recommended when your computer or communications software does not support RTS/CTS flow control. The ASCII values of the XON/XOFF characters are 17 (DC1) and 19 (DC3) respectively.
XON/XOFF flow control is selected with the &K4 command.
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XON/XOFF flow control should not be used with the XModem, YModem or SEAlink file transfer protocols.
Transparent XON/XOFF Flow Control
Transparent XON/XOFF flow control is identical to normal XON/XOFF flow control except the XON and XOFF characters which are part of the normal data stream are encoded to allow flow control with file transfer protocols such as XModem. The ASCII values of the XON and XOFF characters are 17 (DC1) and 19 (DC3) respectively.
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AT Commands
Transparent XON/XOFF flow control is selected by issuing the &K5 command.
Failsafe Flow Control
Failsafe flow control is designed specifically for UNIX computers running the UUCP file transfer protocol. This form of flow control only affects data being transmitted from the computer to the modem.
When the modem’s data buffer approaches maximum capacity, the modem will lower the CTS signal. If the computer does not pause the transmission of data within a few character durations of CTS going low, the modem will send an XOFF to the computer.
When the modem is ready to accept more data from the computer it will assess CTS. If an XOFF was sent to pause transmission, the modem will also send an XON character.
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Failsafe flow control only affects data being transmitted from the computer to the modem. Flow control is not supported for data being transmitted by the modem to the computer. Failsafe flow control is selected by issuing the &K9 command.
The Inactivity Timer
Your modem supports an inactivity timer. When your modem is on line, if it does not communicate with either the remote modem or your computer for a specified length of time, it will hang up and return to local command state.
The AT\T command specifies the number of minutes the modem stays on line when no activity is occurring. The timer may be set from 1 to 255 minutes.
For example:
AT\T5 This allows the modem to be inactive in on-line state for five minutes before hanging up the
default time is 0 minutes the timer is disabled. The inactivity timer is only available when MNP or constant speed mode is selected. It is ignored in variable speed mode.
The Command Timer
If you do not complete an AT command within 60 seconds (that is, type the command and press ENTER), the command will be discarded and an error message will appear. The length of time is controlled by S Register 69 and can be turned off by setting S Register 69 to 0.
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Configuring the Modem
Your modem allows you to tailor its operating parameters to suit your own particular requirements.
The modem uses S Registers to alter the configuration profile. Each S Register contains a decimal value to represent a time delay, an ASCII character or the number of times the phone should ring before the modem answers it (the interpretation of each value differs with each S Register).
The modem allows you to save the contents of the S Registers and certain communication settings under a profile number (0-3) in non-volatile memory (&Wn). This means the entire configuration profile will be retained after you have switched your modem off.
The modem also has factory default settings stored internally, allowing you to change the communication settings and S Register values and then recall the configuration profile stored in your modem when you originally purchased it.
The factory defaults have been selected so most users will be able to make immediate use of their modem, without the need to change any S Register values.
You may restore your modem to its factory defaults at any time:
• Type: AT&F. There is no need to press ENTER with this command.
Viewing the Current Configuration
The &V command allows you to view the current configuration of your modem. When you issue the &V command, your modem sends a list of the current AT command and S Register settings to your computer.
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AT Commands
Error Correction
Error Correction Protocols
This section examines the error correction and data compression features of your modem. The modem offers both V.42 (LAP-M) and MNP® (Microcom Networking Protocol™) error correction protocols. These protocols allow data errors to be detected by the receiving modem, provide flow control between remote systems and improve the overall throughput of data transfers.
Your modem also supports V.42bis and MNP5 data compression. V.42bis is a high performance data compression enabling you to speed up, theoretically by four times, data throughput on some types of data. MNP5 allows you to speed up data throughput by up to two times on some types of data.
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Aust Modems: Before dialling into an AUSTPAC V.22 or V.22bis
service, error correction must be disabled using the \N0 command. Two types of error correction protocols are offered by your modem; V.42 (or LAP-M) and
MNP.
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Error correction protocols are not available when a V.23 connection is established.
V.42 is an international standard for error correction between modems. V.42 ensures any errors introduced into your data by telephone line noise is automatically corrected before it is received by your computer. Because V.42 is a ITU standard, it has become very popular in modems all over the world.
V.42 also supports a fallback mode to MNP, in order to remain compatible with modems introduced prior to V.42.
Before V.42 existed, MNP was the de-facto standard for modem error correction. MNP classes 2-4 are supported by your modem for error-correction (an additional class of MNP is supported for data compression). Because MNP is a far less complex error correction protocol than V.42, it out-performs V.42.
The section titled “Which Error Correction Do I Use?” provides more information about the performance and compatibility merits of V.42 and MNP.
The \N command is used to select the type of error correction used by your modem.
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Data Compression
Two forms of data compression are supported by your modem; V.42bis and MNP 5. V.42bis is based on the Lempel-Ziv compression technique (similar to the techniques used by PC compression programs) and can work with both V.42 and MNP. V.42bis is very good at compressing data that has repetitions of sequences of characters. For example, in an English sentence there are usually repetitions of ‘ions’ or ‘ings’ or ‘ere’; V.42bis works by creating a library of these repetitions and substituting small symbols for them. V.42bis is also able to switch off data compression if the type of data being sent is unsuitable for compression.
MNP 5 is MNP’s stable-mate; it uses ‘run length encoding’ and a variation of the Huffman compression technique. It can double your data throughput on some types of data and MNP 5 works best when there are lots of characters repeated in sequence or a particular character repeated. For example, if you have a file which contained 50 zero characters in sequence MNP 5 will do a good job of compressing them (in some instances, better than V.42bis) – this is run length encoding. Or, if you had a text file where every second character was an ‘i’ and the other characters were random, MNP 5 would again outperform V.42bis (in this instance, Huffman coding provides superior compression). However, MNP 5 does not employ V.42bis’ automatic switching techniques.
If the data you are sending is not suitable for compression (for example, an application file or a graphics file), it can actually take longer to send than if data compression was not being used.
For this reason, it is best to use V.42bis whenever possible. If the modem you connect to does not support V.42bis, it is best not to use MNP 5 unless you are only transferring plain text information. If possible, use one of the many popular data compression programs available for computers to compress applications, graphics and other non-text files.
The %C command is used to select the type of data correction used by your modem.
Reliable Mode
Reliable mode allows the modem to use error correction to connect to another modem. If the modem you attempt to connect to does not support a compatible method of error correction, your modem will hang up and return a NO CARRIER message.
Use \N6 to select V.42/MNP reliable mode, \N4 to select V.42-only reliable mode or \N2 to select MNP-only reliable mode.
Auto-Reliable Mode
Auto-reliable mode allows your modem to use V.42 or MNP if the remote modem also supports these. If the remote modem does not support a compatible type of error correction, your modem will fallback to either constant speed or variable speed mode.
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The \J command determines whether your modem falls back to constant speed or
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AT Commands
variable speed mode.
\N3 selects V.42/MNP auto-reliable mode and \N5 selects V.42-only autoreliable mode. Your modem supports special CONNECT messages for connections made with either reliable or
auto-reliable modes. When the AT\V1 command is issued and your modem connects in either reliable or auto-reliable mode, a response message will be sent to your computer.
When the AT\V0 command is issued (default), your modem will generate standard CONNECT messages for both normal and error-corrected connections. If the X0 command has been issued, the CONNECT/REL will be the only ‘error correction’ response code generated, regardless of the connection speed.
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Issue the %U1 command if you want your modem to issue CONNECT/ LAP-M response codes when a V.42 connection is established. The \V8 command will display details of the error correction and data compression negotiated with the remote modem. This information is displayed immediately before the CONNECT message.
The \V9 command will display details of the error correction and data compression negotiated with the remote modem as well as diagnostic information. This information is displayed immediately before the CONNECT message.
Improving Performance with MNP 10
MNP 10 is neither an error correction or data compression technique. MNP 10 works in conjunction with error correction and data compression to improve the performance of your modem when operating with poor or varying quality telephone lines (as sometimes found with overseas or cellular telephone connections).
With MNP 10 operating, your modem can automatically resize the MNP packets, depending upon the line quality. When an MNP connection is established, data is transferred in small
‘chunks’ known as packets. When the line quality drops, MNP 10 reduces the size of packets
being transferred in order to maintain data throughput. MNP 10 will increase the packet size to take advantage of improved line quality.
If the line quality becomes very good or very bad, MNP 10 can automatically step between line speeds. MNP 10 attempts to use the highest speed applicable to the quality of the telephone connection. If the telephone line quality drops while you are connected to another MNP 10 modem, thus introducing errors into your data, and the smallest packet size is being used, the modems will ‘step-down’ in speed until the error rate become acceptable.
Similarly, if the line quality improves and the modems are using the largest packet sizes, the modems will ‘step-up’ in speed until the best compromise of error rate and line speed is found.
MNP 10 will also make multiple attempts at establishing an error-corrected connection to another modem (more so than MNP 2-4). This gives you a better chance of making a connection
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when operating with poor line quality. If the telephone line drops out, MNP 10 will attempt to reconnect up to the maximum time
permitted by your country’s telecommunications rules. Thus, if there is a short line drop-out, MNP 10 will provide minimal interruption whereas other modems will disconnect entirely.
MNP is the only type of error correction allowed with MNP 10 and is only available when connected to another modem that supports MNP 10. The #K command is used to select MNP
10.
Speed Changes
Although MNP 10 is able to cope with bad telephone connections, your modem must be able to first make a connection with another modem before it can make use of MNP 10. For this reason you may wish to use the AT%H1 command to force your modem to connect at 1200 bps and then ‘upshift’. Most telephone lines will cope with V.32 or V.32bis connections, however connecting at 1200 bps will ensure you make a connection. You may also use the J dial modifier to force your modem to make the initial MNP 10 connection at 1200 bps.
When MNP 10 changes line speed (either up or down) there will be a slight interruption to your communications. For this reason you should always use flow control to ensure data is not lost when MNP 10 changes line speed.
If you wish to establish the connection prior to MNP 10 upshifting or downshifting, issue the %H9 command. This allows you to use the connection before MNP 10 attempts to change the connection speed.
Cellular Modem Users
If you are making modem calls with a cellular phone, issue the AT#K2 command. This tells MNP 10 to try even harder to maintain the connection if your cellular call momentarily drops out.
With such a choice, you may be wondering which combination you should be using. The table below shows the relative performance of each combination of error connection and data compression.
If you are connecting to various makes and models of modems, V.42/V.42bis auto-reliable mode is probably the best alternative (AT\N3%C2). V.42/ V.42bis auto-reliable mode will also connect to another modem that supports MNP with V.42bis data compression. For overseas or cellular connections, use MNP 10 if possible (AT\N3%C2#K1).
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