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AT Commands

Page 61

V.25bis Operations

V.25bis is a modem command set like the AT command set, which allows you to control your
modem. However, V.25bis commands may be issued to the modem in asynchronous or
synchronous mode (AT commands may only be issued when the modem is operating in
asynchronous mode). This means V.25bis is suitable for mainframe and minicomputers which
only support synchronous communications ports. The implementation of V.25bis supported by
your modem is based upon the 1988 revision of the V.25bis specification, however not all
aspects of the V.25bis specification have been implemented.

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V.25bis operation is supported in both smart and dumb modes.

Selecting V.25bis Operation

To select V.25bis mode, issue the appropriate #M command. Three V.25bis modes are supported
by your modem:

o

Asynchronous V.25bis. The modem operates in asynchronous mode using V.25bis command
rather than AT commands. Issue the AT#M1 command to select this mode.

o

Synchronous V.25bis with HDLC framing. The modem communicates and accepts V.25bis
commands in synchronous mode with HDLC framing. Issue the AT#M2 command to select
this mode.

o

Synchronous V.25bis/BSC mode. The modem communicates and accepts V.25bis commands
in synchronous mode with character framing (BSC mode). Issue the AT#M3 command to
select this mode.

The &W and Z commands must be issued after the #M command in order for V.25bis command
mode to be selected. Alternately, issue the &W command after the #M command and switch the
modem off and on or lower DTR (after an &D3 command has been issued).

+

When you reset the modem (for example, you issue the &F command or issue the RST
command or switch the modem off and on), you must issue an ATZ command to select
V.25bis command mode; your modem always resets and powers-up in AT command mode,
regardless of the setting of the #M command.

If your modem has Option switches to select V.25bis operation, the setting of the Option
switches always take precedence over the #M command.

The %R2 option will be required for most V.25bis setups. This setting ensures that the CTS
signal is only asserted when the modem is ready to accept a new command (in command mode).

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Summary of Contents for MD1276A

Page 1: ...MD1276A Global 56K V90 Modem User s Guide 0049 2200 001 Rev A FEBRUARY 2004 0049 2200 500...

Page 2: ...b 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 7...

Page 3: ...s 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 Mo...

Page 4: ...s 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 Dia...

Page 5: ...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...

Page 6: ...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...

Page 7: ...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 follow...

Page 8: ...mmunications 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 Front View The front view of the modem h...

Page 9: ...r 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 shou...

Page 10: ...d 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 o...

Page 11: ...or 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...

Page 12: ...ferring 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...

Page 13: ...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 Z F Z F m l 31200 bps Z F Z F l l 28800 bps Z F m m l 26400 bps Z F m l l 24000 bps Z F l l l 21600 b...

Page 14: ...d 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 sec...

Page 15: ...s 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 d...

Page 16: ...egin 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...

Page 17: ...alue 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...

Page 18: ...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 0123...

Page 19: ...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...

Page 20: ...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 regu...

Page 21: ...ed 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 set...

Page 22: ...ings 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...

Page 23: ...oming 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 b...

Page 24: ...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...

Page 25: ...ing 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 d...

Page 26: ...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 an...

Page 27: ...cols are offered by your modem V 42 or LAP M and MNP Error correction protocols are not available when a V 23 connection is established V 42 is an international standard for error correction between m...

Page 28: ...his 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 a...

Page 29: ...ta 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...

Page 30: ...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 co...

Page 31: ...communicates with the remote modem The best way to operate with error correction and data compression is to set your modem for a constant speed of 57 600 bps 115 200 bps or higher set the terminal spe...

Page 32: ...modem s user and password lists are performed through the Security Menu This menu is displayed when you use the S command Type AT S E A prompt will appear Enter Security Password When you first recei...

Page 33: ...supervisor and has full remote access rights to the remote modem If you key you will be able to issue almost all AT commands on the remote modem and access the full security database if you have the...

Page 34: ...the user names Passwords are never displayed Your computer must be capable of displaying at least 80 characters per line for the user list to be displayed in its correct format The Access Record Selec...

Page 35: ...wers an incoming call it will demand the caller enter a user name and password the following message will appear on the caller s computer screen Enter Name If only one of the modems is configured to u...

Page 36: ...t time to allow most modems to hang up so place an S27 30 in the command Using a 30 second delay means the telephone exchange in most cases will disconnect the call This ensures unauthorised callers c...

Page 37: ...er speed Example FRED NURK HS27 30DT3277502 000 000 is a valid entry The Socket Rocket only supports a security user database of 100 users so if this limit is exceeded you may have to Download the Sec...

Page 38: ...ER for each The modem will ask for a Command or Phone Number Simply enter the phone number you want to recognise at this point If you wish to identify a range of numbers with the same user name as in...

Page 39: ...ll ensure you will only establish encrypted connections The modem can store up to 10 DES Key IV pairs Use AT K to select the Key you wish to use For example AT K5 tells the modem to use the key and IV...

Page 40: ...be extracted from the transmitted message Up to 10 keys can be specified via the AT S Security Menu A key of all zeros is ignored unless it is selected as the current key with the K command The facto...

Page 41: ...x digit DES secondary KEY for the user all 16 digits must be keyed Enter the 16 hex digit DES secondary Initial Value IV for the user all 16 digits must be keyed Enter the 2 hex digit Key Encryptor KE...

Page 42: ...password If the password is the same on both modems then only one password needs to be entered Connection q You will then CONNECT if the username both passwords all of the KEYS IVs and KEs match q Th...

Page 43: ...q Local modem s password is second Automatic Synchronisation q The keys only change after a successful connection is achieved at both ends q If either modem drops out during the security handshake be...

Page 44: ...ssword length accepted by the modem by the E option from the Security Menu Its power on default is 3 characters Uploading and Downloading the SuperSecure Database q To ensure the integrity of your mod...

Page 45: ...e Mode Switch depressed The only way to alter the database or E selection is to enter the Security Menu with the security password and unlock the database with the F Free command The current state LOC...

Page 46: ...y using SuperSecure you now have Ensured that the phone link between two modems is secure Ensured that no other user can access either modem when E2 is enabled q The weak link in the system is now the...

Page 47: ...our modem can only operate over a single two wire connection it will still perform full duplex synchronous communication Half duplex operation could be simulated by controlling the state of the RTS an...

Page 48: ...be able to hang up the modem if the DTR Option Switch is in the DOWN position DTR will always be asserted DTR must be lowered to make the modem hang up To return to asynchronous operation Type AT M0...

Page 49: ...issued Synchronous Mode 2 Synchronous mode 2 is specifically designed for use with dedicated synchronous terminals The phone number to be dialed is stored in the modem the synchronous terminal causing...

Page 50: ...return to quiet asynchronous mode if the carrier is lost for longer than the period defined by S Register 10 or if DTR is lowered Answering Calls Whenever your modem receives an incoming call it will...

Page 51: ...Answer mode automatically To dial or answer raise DTR to return to local command state lower DTR You will require a special phone cable available from your dealer to connect your modem to a leased lin...

Page 52: ...be capable of altering the state of the DTR signal to work successfully with the L2 and L3 commands If your modem has a TALK DATA switch it must be set to DATA Hanging Up There are four ways of hangin...

Page 53: ...mands through HyperTerminal to activate the Audio port AT F Reset AT LINE 1 Set audio port active 3 Issue the following commands to activate Leased Line mode a For Auto Leased Line AT L2 Set auto LL m...

Page 54: ...e button in until the modem beeps twice Setting Up your Modem In most instances your modem will need to be configured prior to entering Dumb mode All configuration of your modem is performed using the...

Page 55: ...Unix computer or multiplexer Place front panel Option switch 4 in the Up position to select Smart mode Connect your modem to a personal computer a Unix computer or a serial server refer to the modem R...

Page 56: ...he Talk Data button Place the handset on hook The OH and CD LEDs glow when the modem connects To hang up Press the Talk Data button to Talk Using the Talk Data Button to Dial You may commence dialling...

Page 57: ...onnects To hang up Have your computer lower the DTR signal or press the Talk Data switch to Talk Using DTR to Dial You may commence dialling by having your computer raise its DTR signal Place front pa...

Page 58: ...calls Place front panel Option switch 4 in the Up position select Smart mode Connect your modem to a personal computer Run a communications program and enter local mode or terminal mode Type ATBx E w...

Page 59: ...s communications Type AT W E The modem set up is saved Place front panel Option switch 4 in the Down position select Dumb mode Place front panel Option switch 6 in the Up position select Answer mode P...

Page 60: ...LC framing F0 Down Up V 25bis sync BSC character framing F0 Down Down DTR controlled by computer F1 Up n a DTR assumed to be asserted raised F1 Down n a DSR acts normally F1 n a Up DSR mimics DTR F1 n...

Page 61: ...bis with HDLC framing The modem communicates and accepts V 25bis commands in synchronous mode with HDLC framing Issue the AT M2 command to select this mode o Synchronous V 25bis BSC mode The modem com...

Page 62: ...riginal settings will be displayed V 25bis Commands Six V 25bis commands are supported by your modem Command Description CRN n Dial phone number n CRS x Dial stored phone number x PRN x n Save n as st...

Page 63: ...V 25bis mode addressed calling similar to using an ATD command and direct calling similar to DTR dialling with the M4 command The CRN command is used to initiate a telephone call The most basic form o...

Page 64: ...ime specified by S Register 7 the modem will return to local command state and send a CFI AB indicator to the computer Due to differences with some older telephone exchanges dial tone detection may no...

Page 65: ...dial modifiers supported in V 25bis mode Direct dialling is also supported in V 25bis dumb mode If your modem supports dumb mode refer to the Dumb Mode Section Answering Calls Your modem is pre config...

Page 66: ...s The Q command is used to select the terminal speed in V 25bis command mode The AT Q command determines whether to use a predefined terminal speed or the terminal speed when the last AT command was i...

Page 67: ...cter encoding technique suitable for use with the computer to which your modem is connected Refer to the chapter titled Command Descriptions for details of the N command Asynchronous Notes The Backspa...

Page 68: ...an abort is received If a succession of V 25bis indications are to be sent to your computer the poll bit or final bit will be set to zero for all but the last V 25bis indication to signify that more V...

Page 69: ...t AT SDR 0 Any ring detected and reported as RING AT SDR 1 1 Single ring detected and reported as RING1 AT SDR 1 0 Single ring detected and reported as RING AT SDR 2 1 Double ring detected and reporte...

Page 70: ...tween the 1st and 2nd RING responses from the modem The message will be in the form DATE mmdd where mm is the month number 01 to 12 and dd is the day number 01 31 TIME hhmm where hh is the hour number...

Page 71: ...Security Database Enter the Security Menu by typing AT S You will then be presented with a request for a Password If you have not specified a password then key ENTER else type in the password The Cal...

Page 72: ...DIAL BACK security entries by the lack of valid AT commands in the Command field Distinctive Ringing Tune Option You may enable a feature to identify a caller by playing a unique tune for each caller...

Page 73: ...delete the call log it can only be explicitly deleted using AT LOG2 If you wish to secure the call log so that it cannot be deleted by unauthorised users the AT LOG2 command can be disabled from the s...

Page 74: ...em returns to local command state it will respond with the message OK This waiting period before and after the escape sequence is called the Escape Sequence Guard Time This allows the modem to disting...

Page 75: ...r it You may change the character used in the Remote Access sequence by changing the value of S Register 67 If the A2 command has been issued to your modem when it receives a request to enter Remote A...

Page 76: ...Page 76 Options Request remote access See Also A command Universal Remote Access S Register 66 Remote Access Guard Time S Register 67 Remote Access Character...

Page 77: ...NTER to quit from the help pages You may also search for certain commands or words S Registers 96 and 97 allow you to change the length and width of each help page to suit your communications software...

Page 78: ...rs the modem to re execute the last command you entered Unlike other commands the Repeat Last Command should not be preceded by an AT nor followed by a carriage return This command must be typed on on...

Page 79: ...a carrier signal in return The B command selects which communication standards your modem will attempt to connect to If a connection cannot be established with the originating modem within the time s...

Page 80: ...mand Speed B0 n Auto Connect B1 Auto Connect B2 Auto Connect B3 V 21 at 300bps B4 Bell 103 at 300bps B5 V 23 at 1200 75bps B6 V 22 at 1200bps B7 Bell 212A at 1200bps B8 V 22bis at 2400bps B9 Auto Conn...

Page 81: ...7bps B52 V 90 at 44 000bps B53 V 90 at 43 333bps B54 V 90 at 46 667bps B55 V 90 at 48 000bps B56 V 90 at 49 333bps B57 V 90 at 50 667bps B58 V 90 at 52 000bps B59 V 90 at 53 333bps B60 V 90 at 54 667b...

Page 82: ...4 at 2400bps B28 V 34 at 4800bps B29 V 34 at 7200bps B30 V 34 at 9600bps B31 V 34 at 12 000bps B40 K56flex at 32 000bps B41 K56flex at 34 000bps B42 K56flex at 36 000bps B33 K56flex at 38 000bps B34 K...

Page 83: ...ATCommands Page 83 See Also A Command Answer B Command Select Communication Standard D Command Dial MS Command...

Page 84: ...ignored by the modem but they will make it easier to read the command line For example ATD 09 111 1234 The D command must be the final command on a command line unless you use the dial modifier As wel...

Page 85: ...sable calling tones hook flash S n dial stored phone number n W wait for dial tone Pause This modifier orders the modem to pause before dialling the rest of the phone number This is useful when using...

Page 86: ...ion at 1200 75 bps CCITT V 23 standard communications If you communicate with another computer in originate mode at 1200 75 bps you will be sending data at 75 bps and receiving at 1200 bps If you have...

Page 87: ...s V 32 MNP 10 is able to automatically adjust the line speed to suit the quality of the phone line For example Type ATDM9999876 E K MNP 10 Cellular Option The K dial modifier allows MNP 10 automatic p...

Page 88: ...ormation regarding how many phone numbers your modem can store For example To dial the stored number two Type ATDS 2 E W wait for dial tone The W modifier causes the modem to wait for a dial tone befo...

Page 89: ...g up return to local command state and send a NO CARRIER message For example To wait for a dial tone and then dial 111 0123 Type ATDW1110123 E See Also Z Command Store Phone Number S Register 6 Wait T...

Page 90: ...you to select whether the characters you type at your keyboard while in the local command state will be echoed back to the screen by the modem Options ATE0 Disable local command state echo ATE1 n Ena...

Page 91: ...mote modem trying to dial in When you issue the H1 command the modem goes off hook but will not generate carrier or answer tones The H2 command causes the modem to go off hook after the current connec...

Page 92: ...mmand to display these codes Options ATI0 Display numeric identity code ATI1 Return a checksum of modem s firmware ATI3 Display model identifier ATI4 Display code revision and creation date ATI5 Displ...

Page 93: ...ice environment so most users will not need to change the preset volume of their modem There are four speaker volume levels 0 Lowest volume level 1 Low volume level 2 Medium level 3 Highest volume lev...

Page 94: ...e volume control via the L command Options ATM0 Speaker is always off ATM1 n Speaker is on whenever the modem is dialling or answering a call When a connection is established the speaker is switched o...

Page 95: ...uce the levels of interference and improve data transmission Retrains cannot overcome noise on the line Options ATO0 Enter on line state ATO1 Enter on line state and force equaliser retrain 2400bps an...

Page 96: ...200 bps V 32bis V 34 ATO30 Change line speed to 21 600 bps V 32bis V 34 ATO31 Change line speed to 24 000 bps V 32bis V 34 ATO32 Change line speed to 26 400 bps V 32bis V 34 ATO33 Change line speed t...

Page 97: ...tch the messages off no response codes will be displayed on your screen with the exception of responses from the ATSn command and AT V command Options ATQ0 n Send response codes to the screen ATQ1 Do...

Page 98: ...autobauding at 230kbps the character format and parity is specified by the AT ICF command the defaultis 8 bits no parity Your modem can autobaud at 1 200 bps through to 230 400 bps IBM PC and compatib...

Page 99: ...locked terminal speed no autobaud ATR115 115 200 bps locked terminal speed no autobaud ATR230 230 400 bps locked terminal speed no autobaud ATR460 460 800 bps locked terminal speed no autobaud K56 mod...

Page 100: ...mber of the S Register you want to read For example The number of times the modem will allow the phone to ring before answering an incoming call is determined by the value in S Register 0 To see the c...

Page 101: ...as being a carriage return is determined by the value in S Register 3 The default value of this register is 13 To change this value to 15 Type ATS3 15 E It is important to alter values only in those...

Page 102: ...d and executed CONNECT 1 Carrier detected and connection established RING 2 Ringing signal detected NO CARRIER 3 Carrier lost or not detected ERROR 4 Error in command string or command line longer tha...

Page 103: ...r terminal speed when it connects to another modem Options ATW0 The CONNECT message reports the terminal speed ATW1 The CONNECT message reports the terminal speed ATW2 n The CONNECT message reports th...

Page 104: ...response codes or you can display sets of extended response codes depending on the capabilities of your modem Response Code 8 NO ANSWER is controlled by the Wait For Quiet Answer dial modifier REL Re...

Page 105: ...Also Q command Quiet Suppress Response Codes V command Verbal Response Codes W command Connection Speed Information V command Error Correction Response Codes U command V 42 Response Codes S Register...

Page 106: ...iguration into profile 2 by using W2 you can restore the modem to the values contained in saved configuration 2 by Type ATZ2 E To restore factory defaults use the F command The Zn command must be the...

Page 107: ...gths of 8 9 10 or 11 bits The modem will only match the speed of your computer when 10 bit or 11 bit characters are selected Range 0 4 Options AT B0 8 bit characters AT B1 9 bit characters AT B2 10 bi...

Page 108: ...an interruption to the DCD signal which might cause the application to think that the line has been lost The C command will only have effect when the DCD option switch is in the UP position and T0 is...

Page 109: ...n The modem will hang up return to local command state and disable auto answer whilst DTR is low is not asserted To enable auto answer the DTR signal must be asserted The computer must assert DTR befo...

Page 110: ...profiles in non volatile memory will be restored to factory defaults Type AT F Do not press ENTER A message will be displayed OK If you do not receive this message re check the connection of your mode...

Page 111: ...K0 D2 N1 C0 The F2 command selects synchronous mode factory defaults The defaults selected are B13 E0 Q1 M2 You must use the W command if you wish to save the default values to nonvolatile memory and...

Page 112: ...uard tone is a predetermined frequency generated by the modem to supervise the communications path The G command only affects V 22 and V 22bis connections Options AT G0 n Do not generate guard tones A...

Page 113: ...signal With H0 selected the RxC signal will be active whenever a synchronous mode is selected With H1 selected the clock will only be present after a connection has been established to another modem...

Page 114: ...Options AT K0 Flow control disabled AT K3 n RTS CTS hardware flow control The modem and computer use the CTS Clear to Send and RTS Request to Send signals on the RS 232 serial connection to control d...

Page 115: ...em to the computer Range 0 3 5 9 See Also N command Operating Mode Q command Extended Flow Control S Register 80 Flow Control High Water Mark S Register 81 Flow Control Low Water Mark S Register 82 Fa...

Page 116: ...ed to issue the ATA or ATD commands L2 selects Originate mode automatically and L3 selects Answer mode automatically The modem s TALK DATA switch must be set to DATA and DTR must be raised to make the...

Page 117: ...T M2 Synchronous mode with dialling invoked by the DTR signal The modem remains in asynchronous mode while it is on hook dialling or answering You must issue the AT D2 command prior to using this sync...

Page 118: ...Page 118 Range 0 2 4 See Also D command Controlling DTR X command Synchronous Clocks Z command Stored Phone Number...

Page 119: ...connection by either lowering the DTR Data Terminal Ready signal or by sending a character except a null or line feed character to the modem If you have used the N0 command and the DTR Option switch...

Page 120: ...Request to Send and CTS Clear to Send signals when operating in synchronous mode The R command is ignored whenever asynchronous mode is selected R1 overrides the R command Options AT R0 n CTS follows...

Page 121: ...only take effect when the DSR option switch is in the UP position see your Dumb Mode Section for details S overrides the S command Options AT S0 n DSR signal will always be asserted AT S1 DSR signal a...

Page 122: ...the contents of stored profiles 0 to 3 respectively For this command V is different from V0 The V command must be the last command on the command line Options AT V View active configuration profile A...

Page 123: ...mand restores the specified profile to the active configuration See the topics of S Register Settings and Modem Memory in the S Register section of this Guide for a description of the different types...

Page 124: ...nd applies it to pin 15 of the RS 232 socket AT X1 Clocks generated by computer external clocking The clock generated by the computer or terminal received on pin 24 of the RS 232 socket is directly ap...

Page 125: ...r profile is selected as the Active profile when the modem is switched on and also when D3 is selected and DTR drops Options AT Y0 Select stored profile 0 on power up AT Y1 Select stored profile 1 on...

Page 126: ...e number an AT a D Dial command an S Stored number dial modifier If you are using synchronous mode 2 do not use the return to local command state dial modifier in the number The stored phone numbers a...

Page 127: ...orrect the following message appears Incorrect Please try again You must re initiate the remote access by typing the remote access sequence again before you can re type the password If the password yo...

Page 128: ...Page 128 Range 0 2...

Page 129: ...22 for its 1200 bps originate speed when B0 or B2 is selected By default your modem will use V 23 as its 1200 bps connection standard with B0 selected and V 22 with B2 B1 reverses these settings Optio...

Page 130: ...er you dial is answered by a person rather than a modem or other electronic device It also allows an electronic device to select the appropriate operating mode V 25 tones indicate to the answerer of a...

Page 131: ...he caller if supplied by the network or if saved in the security database This format is compatible with standard Rockwell modem responses If the extended response option is selected AT CID3 the follo...

Page 132: ...ler ID disabled AT CID1 Caller ID enabled AT CID2 Caller ID enabled with response to host in hex format AT CID3 Caller ID enabled with extended response See Also Refer to the section on Caller ID S Co...

Page 133: ...g procedures or DTR dialling will be used when V 25bis mode is selected Refer to the section titled Direct Dialling which appears in the V 25bis chapter for details of how direct dialling works Option...

Page 134: ...ity Section WARNING Only reliable error correction modes should be used with DES This ensures only DES connections will be established with another modem Refer to the N command for details of the erro...

Page 135: ...ATCommands Page 135 AT H Display Help The H or command may be followed by a command or keyword to display a description of a command See Also Command Display Commands...

Page 136: ...d line mode This mode is specified by default Some modems still use the standard PSTN handshake for leased line connections Use I1 to connect to these modems in V 22bis leased line mode Options AT I0...

Page 137: ...T J0 command when you are certain the other modem is a V 42 modem WARNING You will not be able to communicate with a non V 42 modem if the AT J0 command has been issued regardless of the setting of th...

Page 138: ...NP 10 over bad telephone lines or cellular connections issue the H1 command before dialling or use the J or L dial modifiers This ensures an MNP 10 connection is established Issue the AT K2 command fo...

Page 139: ...ons for an explanation of V 25bis The M command doesn t take effect until the an AT W and an ATZ command are issued Options AT M0 n AT command operation AT M1 Asynchronous V 25bis AT M2 Synchronous V...

Page 140: ...coding for V 25bis synchronous operation This command only takes effect when a synchronous V 25bis operating mode is selected Before setting the N command check which character encoding method is expe...

Page 141: ...haracters are ignored if the modem buffers overflow AT O1 Modem disconnects if the terminal buffer overflows that is data from the computer to the modem S Register 42 the Disconnect Reason is set to 1...

Page 142: ...odem will use the speed at which you issued the last AT command for V 25bis mode Alternatively you may issue one of the other Q commands to select a specific V 25bis terminal speed Options Q0 Use last...

Page 143: ...e R command will enable remote control mode After the command is issued any commands the remote modem sends to your modem will be acted upon by your modem as if commands were being issued from the com...

Page 144: ...load Security file to host U Upload Security file from host L DES Params Keys Call Log LOCK F FREE Encryption and Dial Enable K OutDial Disable M Dial Stored Phone Numbers Only N Change Database Local...

Page 145: ...d is used to select the character set to be used when V 25bis mode is selected ASCII characters are used by most computers EBCDIC characters are used primarily by IBM mainframe computers Options AT U0...

Page 146: ...ssue If you issue an unsupported command the modem responds with an OK message With V1 selected if you attempt to issue an invalid command or read or write to a reserved S Register the modem will retu...

Page 147: ...e 147 AT B AutoAnswer Setting The B command sets the number of rings before your modem answers The default setting B0 turns off AutoAnswer Options AT B0 n S0 0 No AutoAnswer AT B2 S0 2 Modem answers a...

Page 148: ...he Error Correction Section of this guide When selecting a data compression mode error correction must also be selected See the N command for details of error correction Options AT C0 Compression disa...

Page 149: ...value of 0 or 255 disables the disconnect delay If you have defined a disconnect delay the modem will attempt to empty the contents of its data buffers before hanging up If the modem s buffers are emp...

Page 150: ...e connection The E2 command allows an originating modem to automaticallyr etrain to a lower speed if the line quality deteriorates This only works between two modems both supporting the feature In all...

Page 151: ...ion switches 1 and 2 may be used to control the DTR and DSR signals or select V 25bis operation Refer to the Dumb Mode section for details Options AT F0 A B switches control V 25bis function AT F1 n S...

Page 152: ...P 10 Options AT H0 n Use the B setting for initial MNP 10 connection speed The B setting is the maximum speed AT H1 Initial connection speed is made at 1200 bps V 22 The maximum speed is defined by th...

Page 153: ...to a remote modem and is ready to send data This command will interfere with the Abort Connection command N if your computer cannot send characters to the modem when CTS is low Options AT K0 n CTS op...

Page 154: ...l Level The L command allows you to display the received signal level The value returned is a 3 digit number for example 009 9 dBm 043 43 dBm AT L Display received signal level Examples Type AT L E Th...

Page 155: ...he transmit level to 15dBm Type AT L15 E WARNING Do not change the transmit level of your modem unless you have a specific reason for doing so Changing the transmit level of your modem may adversely a...

Page 156: ...M0 command refer to the table on the underside of your modem to determine the line speed If you have issued the M1 command Mode 1 LED will illuminate whenever the line quality is judged to be poor Mod...

Page 157: ...ATCommands Page 157 AT N Non Standard Terminal Speeds Options AT N0 n Standard Baud Rates AT N1 Standard to 14400 then 20800 31200 41600 and 62400 AT N2 Standard to 38400 then 51200...

Page 158: ...t before or after the DCD signal is asserted by your modem Some Unix computers require the CONNECT message to appear after DCD is asserted In this case the AT P1 command should be used Options AT P0 n...

Page 159: ...21 V 23 or Bell 103 connections Alower value indicates a good quality connection Values above 40 indicate a bad quality line signal and that you should shift to a lower speed or use MNP10 Values belo...

Page 160: ...This command overrides any R setting The R command does not revert to the default setting after an ATZ AT F or modem power off is performed Options AT R0 n R command determines the state of CTS AT R1...

Page 161: ...dem does not have one eg Pocket Rack Modems If your modem has a DSR option switch the switch setting will take preference to S S1 overrides any S setting The S command does not revert to the default s...

Page 162: ...ne eg Pocket Rack Modems If your modem has a DCD option switch the switch setting will take preference to T T1 overrides any setting of C The T command does not revert to the default setting after an...

Page 163: ...and is issued a CONNECT REL 10 or CONNECT LAP M message will be sent to your computer to indicate an MNP 10 or V 42 connection has been established The U command does not revert to the default setting...

Page 164: ...ame a particular service provided by this modem or simply to identify the modem itself The message to be sent to the remote modem is specified by using the W command If used with dial back security th...

Page 165: ...d allows you to select the maximum block size to be used by your modem over an MNP error corrected connection Options AT A0 64 character block size AT A1 128 character block size AT A2 192 character b...

Page 166: ...to 0 9 seconds The default length of breaks generated by the modem is 0 3 seconds The K command determines how the modem will react when a break sequence is received This command stores the break len...

Page 167: ...odem the modem will fall back to Constant Speed mode Selecting J1 will cause the modem to operate in Variable Speed mode If an error corrected auto reliable connection cannot be established with anoth...

Page 168: ...nding and receiving modems and immediately send Break K3 Immediately send Break K5 Send data in buffer before sending Break B command issued during a Constant speed or error corrected connection K0 1...

Page 169: ...returns to on line state If the break sequence is received by the modem while it is in local command state and maintaining a variable speed connection the break will be ignored Breaks received from a...

Page 170: ...eed If the terminal speed is higher than the modem s maximum line speed the modem will attempt to connect using its highest speed Flow control will be ignored when your modem is configured for variabl...

Page 171: ...ATCommands Page 171 See Also B command Communications Standard K command Flow Control J command MNP Fallback J command V 42 Detect Phase Range 0 7...

Page 172: ...es the CTS Clear To Send signal to pause data flow but will not respond if the computer changes the state of the RTS Request To Send signal AT Q3 CTS RTS flow control 1 The modem and computer use the...

Page 173: ...nds Page 173 AT S Display Active Configuration The S command allows you to display the current active configuration The following is a sample of the S command output Options AT S Display Active Config...

Page 174: ...g up and return a NO CARRIER message with S42 12 The inactivity timer is only available when error correction or Constant Speed mode is selected It is ignored when variable speed mode synchronous comm...

Page 175: ...the case disable the error correction response codes When disabled the modem will generate standard CONNECT messages for both error correction and normal connections Options AT V0 n Disable error cor...

Page 176: ...acters sent from a remote system to your modem When the modem is configured for XON XOFF flow control passing through XON XOFF characters may interfere with the modem s control of data flow It is usua...

Page 177: ...Y from Stored Keys The K command allows the user to select the DES key from the 10 available stored keys Default 0 Range 0 9 See Also S Security E Encryption The Security Encryption section contains i...

Page 178: ...data will appear as rubbish to the host which will discard it however the receiving modem in V 13 mode will recognise the stream and convey it to the host via the DCD RSLD line DCD high indicates remo...

Page 179: ...l ask for the current password before prompting for a new password The user will then be asked to repeat the new password for verification If the user is not connected the name of the user whose passw...

Page 180: ...mmand allows you to select whether the modem will redial the last number dialed automatically If enabled the modem will dial the last number after 10 seconds Options AT T0 n Disable auto call redial A...

Page 181: ...8 1 compression on some file types Some modems do not correctly negotiate the dictionary size in these cases the user should reduce the dictionary size to 2 048 entries 4 1 compression ratio If the r...

Page 182: ...only by the maximum command line size 80 The message may include new lines which are indicated by using the character If W1 is enabled the text you have specified will be displayed at the end of the V...

Page 183: ...e performance you need to be able to escape to command mode To allow these diagnostics to take place the user may select the Y1 option before making a synchronous connection and then attaching a async...

Page 184: ...x is AT ICF format parity Format can be 0 n auto 1 8 data bits no parity 2 stop bits 2 8 data bits with parity 1 stop bit 3 8 data bits no parity 1 stop bit 4 7 data bits no parity 2 stop bits 5 7 dat...

Page 185: ...ection modulation speed DTE speed For example 1 DTE speed 19200 bps Modem configuration MS 11 1 300 19200 Maximum obtainable modulation speed 19200 bps 2 DTE speeds 38400 bps Modem configuration MS 11...

Page 186: ...however there are modulations for which there is no automatic negotiation for example Bell 212 mod 69 For automode 0 automode disabled i e fixed modulation If max_rate is within the rates supported by...

Page 187: ...way down to V 21 300 bps For example MS 11 1 300 16800 selects automode starting at V 34 16800 bps no comparable S37 command MS 9 1 300 12000 selects automode starting at V 32 12000 bps same as S37 1...

Page 188: ...S Reporting supported options Nn Automode 1 Use of the Nn command is not recommended but is provided for compatibility with existing communication software 2 This command is product dependant The ATB...

Page 189: ...nsisting of supported options Options MS Example MS 0 1 2 3 8 9 10 11 12 56 64 69 74 0 1 300 56000 300 56000 See Also MS Reporting selected options MS Select modulation Range MS list of supported mod...

Page 190: ...22bis or V 22 MNP10 connection MNP10 has the ability to make decisions regarding line quality and will request a change in speeds if it decides the phone line is not sufficient quality to maintain th...

Page 191: ...he Call Logging Function AT LOG automatically records the Date Time Phone Number and Name of any inbound call that has Caller ID information In addition the modem will also log all outbound calls that...

Page 192: ...or approximately 400 calls AT LOG2 Delete call log confirming the deletion with Y AT F and AT F do not delete the call log it can only be explicitly deleted using AT LOG2 If you wish to secure the cal...

Page 193: ...32 compromise equaliser When operating over cellular connections it may be desirable to switch off the V 32 compromise equaliser For dial up lines the equaliser should be switched on Options AT E0 Dis...

Page 194: ...cide to accept an incoming call after issuing the DIC command For details refer to the V 25bis Operations section of this guide Options CIC Accept an incoming call after the DIC command has been issue...

Page 195: ...change the characteristics of dialling Definitions for all modifiers appear on the following pages Modifier Meaning pause wait for dial tone hook flash Options CRN12345 Dial number 12345 pause This m...

Page 196: ...al tone waiting period from the default period of 30 seconds by changing the value in Register 7 When using the modifier the length of time your modem waits for a dial tone is determined by the value...

Page 197: ...sic form of the CRS command is CRS n where n is the stored phone number you wish to dial For example To dial stored phone number one Type CRS 1 E Refer to your Modem Commands for details of how many p...

Page 198: ...t to your computer You then have the number of seconds defined by S Register 71 to disregard the call If you issue the DIC command the call will be ignored otherwise the modem will answer the call aft...

Page 199: ...o store and n indicates which of the stored phone numbers it will be saved as Stored phone numbers may contain up to 20 characters including dial modifiers Options PRN2 12345 Store the phone number 12...

Page 200: ...eturns the modem to the last saved configuration and causes it to perform a power on self test When you issue the RST command you must issue an ATZ command to select V 25bis command mode Your modem al...

Page 201: ...Register If you want to change the register setting use the Set Register command Sn x For example To change the setting of your modem so the modem waits five seconds for a dial tone before starting to...

Page 202: ...chase the default parameters in ROM will control the modem If you have made changes and stored them as profiles in non volatile memory using the Write Configuration Wn command where n profile 0 1 2 or...

Page 203: ...odem will wait before answering an incoming call If you place a value of 0 in this S Register auto answer operation will be disabled The default value for S Register 0 is 0 the modem will not answer a...

Page 204: ...er 1 contains a decimal value from 0 to 255 indicating the number of rings detected S Register 1 is incremented each time a ring is detected It will be cleared if no ring occurs within 8 seconds of th...

Page 205: ...he modem will recognise three characters as the escape sequence Setting this register to a value greater than 127 disables the modem s recognition of the escape character Examples ATS2 36 Recognise th...

Page 206: ...racter S Register 3 contains the ASCII value of the character recognised by the modem as the Carriage Return character in local command state Default 13 Example ATS3 127 Recognise the DEL character as...

Page 207: ...Character S Register 4 contains the ASCII value of the character recognised by the modem as the Line Feed character in local command state Default 10 Example ATS4 13 Recognise the Carriage Return cha...

Page 208: ...e ASCII value of the character recognised by the modem as the Backspace character in local command state The preferred values for this register are ASCII codes 0 to 32 or 127 Default 8 Example ATS5 12...

Page 209: ...tone This provides slow telephone exchanges the opportunity to apply a dial tone to the line before the modem attempts to dial If the W dial modifier is included in the phone number being dialed the v...

Page 210: ...hake The answering modem has 57 seconds to complete the handshake after starting answer tone This register is also used by the W modifier to determine how long the modem will wait for a dial tone to b...

Page 211: ...when it encounters a comma the pause dial modifier in a dialling sequence UK Modems Changing S Register 8 from its default value may invalidate the approval of your modem Examples ATS8 6 Wait six seco...

Page 212: ...line noise being mistaken by the modem as a carrier signal If you have previously issued an AT C0 command or placed the DCD option switch in the DOWN position the modem will assert the DCD signal reg...

Page 213: ...will wait after the carrier has been lost before hanging up If a value of 255 is placed in this register the modem will not hang up after the carrier is lost from the remote modem In this case you mus...

Page 214: ...Tone Timing S Register 11 contains the time in thousandths of a second of the duration and spacing of tones when tone dialling DTMF tones Examples ATS11 120 Space tones at 0 120 second intervals Defa...

Page 215: ...must maintain silence on the line for one second then type in rapid succession and then maintain another second s silence The guard time is in units of 20 milliseconds or 1 50 of a second S Register...

Page 216: ...6 Test in Progress read only S Register 16 contains the number of the T test command in progress If no test is in progress S16 is 0 Examples ATS16 Default 0 See Also T Self Test S Register 18 Test Tim...

Page 217: ...ommands You can terminate any test by issuing an AT T0 command or by allowing the time in the Test Timer to expire Placing a value of 0 in S Register 18 disables the Test Timer forcing you to use an A...

Page 218: ...me in hundredths of a second the DTR Data Terminal Ready signal must remain low before the modem will recognise a loss of DTR Examples ATS25 8 DTR must remain low for 0 08 seconds before the modem wil...

Page 219: ...the modem will wait for the period defined by S Register 26 before asserting the CTS Clear To Send signal when R0 is selected Values in this register are in tenths of a second Examples ATS26 15 Wait 1...

Page 220: ...g allows the calling modem sufficient time to hang up before the modem begins to call back A 30 second delay should be sufficient time to allow most modems to hang up When you are not using security c...

Page 221: ...ormed by your modem when the dial modifier is executed Some PABXs may require a different hook flash length to the standard 0 5 seconds The value held in S Register 29 is in hundredths of a second Exa...

Page 222: ...10 minutes of inactivity on the line Default 0 See Also T command Set Inactivity Timer Range 0 255 Voice Mode This S Register sets how long the modem remains in voice mode when on hook and in non aut...

Page 223: ...S Registers Page 223 See Also ATS105Voice Dead man Timer Range 0 255...

Page 224: ...lue the modem will demand a high quality connection Setting a high value in S33 will allow the modem to operate on degraded lines without invoking retrains Avalue of zero will also disable automatic E...

Page 225: ...ents of its data buffers before actually going on hook If the modem empties its buffers before the defined disconnect delay expires the modem will hang up immediately The modem will respond with NO CA...

Page 226: ...P class 3 or 4 connection 12 Inactivity timer expired 13 Unable to establish MNP connection with reliable mode selected 14 Retrain failed 15 A break sequence received from the remote modem after the Y...

Page 227: ...mmand determines the length of breaks to the remote modem Each unit is equivalent to 0 02 second S Register 43 does not affect the length of the break generated by the modem when variable speed mode i...

Page 228: ...lity connection Setting a high value will allow the modem to operate on degraded lines without invoking retrains Avalue of zero will disable automatic EQM retraining for V 22bis The value in this regi...

Page 229: ...of time in hundredths of a second that the DTR Data Terminal Ready signal must be high before the modem will recognise DTR being asserted Example ATS57 8 DTR must be high for 0 08 seconds before the...

Page 230: ...r a V 42 detection pattern from the other modem The originating modem sends the pattern then waits for a reply the answering modem waits for the pattern then sends one in reply Changing the value of t...

Page 231: ...racter has been defined as asterisk you must maintain silence on the line for one second then type four asterisks in rapid succession then maintain another one second s silence The guard time is in un...

Page 232: ...t value of this register is 42 asterisk character The modem will recognise four characters as the remote access sequence Examples ATS67 36 Recognise four characters as the remote access sequence Defau...

Page 233: ...t before you complete a command an ERROR message will be sent by the modem The default value of 60 allows you 60 seconds between the time you have typed AT and when you press the ENTER key A value of...

Page 234: ...seconds defined by S Register 71 allowing you to issue the DIC command if you do not wish to accept the call For more details refer to the section titled Answering Calls which appears in the V 25bis O...

Page 235: ...prior to a new disconnect reason being placed in S Register 42 This register is mainly used to allow a remote modem to dial in invoke remote access and enquire as to why the last connection failed For...

Page 236: ...und reason for doing so the high water mark should never be set higher than 75 Using a higher water mark may cause problems with computers that are slow to respond to your modem s flow control Each un...

Page 237: ...f this S Register unless you are an experienced communications user An inappropriate value may cause flow control between your computer and modem to become unreliable Each unit is equivalent to 5 of y...

Page 238: ...l it will ignore the CTS signal and keep sending data S82 determines the number of characters the modem will accept after dropping CTS before sending XOFF If the value is too low some hosts will not r...

Page 239: ...anged by storing the decimal number equivalent of the binary value represented bt the total of the bits Examples ATS95 46 Displays the CARRIER PROTOCOL and COMPRESSION messages and adds the REL to the...

Page 240: ...Help page and the Configuration Profile V You may change the width of each page to suit your computer Examples ATS96 40 Set the Help page width to 40 characters Default 80 See Also S Register 97 Help...

Page 241: ...of each Help page and the Configuration Profile V You may change the length of each page to suit your computer Examples ATS97 10 Set the Help page length to 10 lines Default 24 See Also S Register 96...

Page 242: ...d when no characters are received from the computer If the Dead Man timer expires the modem returns to data mode This register may also be accessed by writing to S30 when in voice mode Examples ATS105...

Page 243: ...e AT V7 cr You will be presented with a realtime reading from the modem similar to the following Speed EQM max min av hex limit Rx Dbm S10 S09 C cts loss S rlsd loss 19200 075A 008 007 007 07 016 029...

Page 244: ...Register sets the average EQM limit that the modem must do better than to achieve an upshift The default is 16 which means that for an upshift to be possible the average EQM must be 16 or lower for S...

Page 245: ...seconds after 12 that the modem must maintain the average EQM below the S123 value The default is 30 which means that for an upshift to be possible with a setting of S123 16 the modem must maintain an...

Page 246: ...21 600 bps 36 CONNECT 24000 Connection at 24 000 bps 37 CONNECT 26400 Connection at 26 400 bps 38 CONNECT 28800 Connection at 28 800 bps 95 CONNECT 31200 Connection at 31 200 bps 97 CONNECT 33600 Conn...

Page 247: ...ction at 30 667 bps 181 CONNECT 32000 REL Connection at 32 000 bps 182 CONNECT 33333 REL Connection at 33 333 bps 183 CONNECT 34667 REL Connection at 34 667 bps 184 CONNECT 36000 REL Connection at 36...

Page 248: ...mode or local command state Clear To Send CTS Pin 5 This signal indicates to the computer the modem is ready to begin receiving data from it When RTS CTS flow control is enabled the CTS signal is use...

Page 249: ...ronous mode is selected This signal is used by your computer to synchronise incoming data The receive data clock is always derived from the receive carrier signal Data Terminal Ready DTR Pin 20 This s...

Page 250: ...Page 250 Standard RS 232 Examples...

Page 251: ...at 1200 75bps B6 V 22 at 1200bps B7 Bell 212A at 1200bps B8 V 22bis at 2400bps B9 Auto Connect B10 V 32 at 4800bps B11 V 32 at 7200bps B12 V 32 Non TCM at 9600bps B13 V 32 at 9600bps B14 V 32bis at 12...

Page 252: ...B55 V 90 at 48 000bps B56 V 90 at 49 333bps B57 V 90 at 50 667bps B58 V 90 at 52 000bps B59 V 90 at 53 333bps B60 V 90 at 54 667bps B61 V 90 at 56 000bps E0 Disable local command state echo E1 n Enabl...

Page 253: ...peed to 4800 bps V 32bis V 34 O24 Change line speed to 7200 bps V 32bis V 34 O25 Change line speed to 9600 bps V 32bis V 34 O66 Change line speed to 12 000 bps V 32bis V 34 O27 Change line speed to 14...

Page 254: ...e active configuration from stored profile 0 Z1 Restore active configuration from stored profile 1 Z2 Restore active configuration from stored profile 2 Z3 Restore active configuration from stored pro...

Page 255: ...tored configuration profile 2 V3 View stored configuration profile 3 V8 View differences between active configuration and default settings of the S Registers Wn Write Configuration Parameters W0 Save...

Page 256: ...B setting for initial MNP 10 connection speed The B setting is the maximum speed H1 Initial connection speed is made at 1200 bps V 22 The maximum speed is defined by the B setting H2 Initial connectio...

Page 257: ...e inactivity timer T35 Set inactivity timer to 35 minutes V0 n Disable error correction response codes V1 Enable error correction response codes V8 Enable error correction response codes plus details...

Page 258: ...Commands SDR n x where n 0 to 7 default 0 x 0 Disable Distinctive Ring response suffix x 1 Enable Distinctive Ring response suffix default Dial Modifiers D Dial Pause Return to local command state R...

Page 259: ...42 Detection Timer 75 0 75 second 0 255 66 Remote Access Guard Time 10 1 255 67 Remote Access Character 42 the character 1 125 69 Command Line Time out 60 0 255 71 Ignore Incoming Call 0 0 30 74 Disc...

Page 260: ...Page 260...

Page 261: ...s in a continuous manner smooth transitions to different levels ANSI American National Standards Institute primary standards development body in the USA ASCII American Standard Code for Information In...

Page 262: ...h it is often used in this way Compare with bit rate Baud Rate Number of discrete signalling events per second not necessarily the same as bits per second For example a V22bis 2400 bps modem uses a 60...

Page 263: ...ers and provide the ability to download public domain software and exchange electronic mail Byte A grouping of bits to specify a single character usually consisting of eight consecutive bits See also...

Page 264: ...sion characteristics of the line Conferencing A form of bulletin board that allows real time communication between multiple users In the U S A conferencing systems have been established to allow large...

Page 265: ...been established and that data can be sent Cyclic Redundancy Check An error detection technique in which a data validation value is mathematically derived from a block of data and transmitted at the...

Page 266: ...the DCE Usually a modem to accept data from the DTE usually a terminal or computer Data Terminal Equipment DTE The equipment which provides the data source and or receiving end of a data transmission...

Page 267: ...omputer via the public switched telephone network Dial Tone A call progress signal returned by a telephone switching machine to indicate that it is ready to accept a telephone number Dibit A grouping...

Page 268: ...re transmission of characters received by either the modem or remote system back to the DTE Echoplex Method of verification of transmitted data by echoing the characters transmitted back to the sourc...

Page 269: ...so that if small errors are detected the correct information can be recreated by the receiving end without requiring a re transmission Frame See Block Frequency Modulation FM A method of transmitting...

Page 270: ...software Hardware Handshaking The use of special RS 232 signals to halt or commence the flow of data between two computers or terminals between computers and modems or between facsimile machines See...

Page 271: ...d services on line or both The code is known only to the user and protects the user from unauthorised access to her his account See also Password Input Information transferred into a computer from som...

Page 272: ...ems only Refers to pressing of numeric keys to access an item from an index L Leased Line A telephone line permanently connecting two or more locations It does not have any switching equipment associa...

Page 273: ...uter system composed of a large number of peripherals and comprehensive software Mark One of the two possible states of a binary data element The closed circuit and idle condition in a teleprinter cir...

Page 274: ...or natural disturbances which can produce errors in transmission Null Modem See Modem Eliminator O Odd Parity Odd parity refers to the appending of a 0 or 1 value bit to the data bits of a character...

Page 275: ...rds used with bulletin boards varies from one system to another On most videotex systems a four character password is used See also ID Number PBX See PABX PEP See Packetised Ensemble Protocol Peripher...

Page 276: ...eotex systems carry public domain software for users to download See also Shareware Public Switched Network Telephone system providing circuit switching to many customers Pulse An abrupt and relativel...

Page 277: ...ems and computers Also known as CCITT V24 RTS An acronym for Request To Send This signal is generated by the terminal or computer indicating that it requires to send data to the modem Used mainly in h...

Page 278: ...control characters are sent from one terminal to the other in order to halt or re commence the flow of data See also Hardware Handshaking SOH Start Of Header used in synchronous transmissions indicat...

Page 279: ...ding See Software Downloading Teleload See Software Downloading Teletext A non interactive information system that was the predecessor to videotex systems Teletext terminals consist of a specially mod...

Page 280: ...r Viewdata Videotex systems usually operate over switched telephone lines and allow 40 columns by 24 lines of colour text and graphics to be displayed on the screen Information is arranged in pages ea...

Page 281: ...ncluded transfer of file names multi file transfers increased reliability of error checking and increased data throughput Z ZModem Designed to rectify some of the limitations associated with YModem as...

Page 282: ...32 9600bps ITU T V 32 7200bps ITU T V 32 4800bps ITU T V 22bis 2400bps ITU T V 22 1200bps ITU T V 23 1200 75bps ITU T V 21 300bps Bell 212A 1200bps Bell 103 300bps ITU T V 17 fax 12 000 14 400bps ITU...

Page 283: ...and Transparent XON XOFF async mode only Error Correction V 42 MNP 2 4 MNP10 Data Compression V 42bis MNP 5 Encryption DES 64 bit Cypher Feedback Aust only SuperSecure Environmental Operating 0 to 45...

Page 284: ...may make changes in its technical operations and procedures If any such changes affect the compatibility or use of this device the telephone company is required to give adequate notice of the changes...

Page 285: ...ations Repairs to certified equipment should be made by an authorized Canadian maintenance facility in this case your supplier Any repairs or alterations made by the user to this equipment or equipmen...

Page 286: ...the Class A limits for radio noise emission from digital apparatus set out in the Radio Interference Regulation of the Canadian Department of Communications Le pr sent appareil num rique n met pas de...

Page 287: ...al manera que la tierra fisica y la polarizaci n del equipo no sea eliminada 13 Los cables de la fuente de poder deben ser guiados de tal manera que no sean pisados ni pellizcados por objetos colocado...

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