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IBM 3872, User Manual, Page: 5 / 76

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Summary of Contents for 3872

Page 1: ...Systems GA27 3058 3 File No 3872 09 IBM 3872 Modem User s Guide...

Page 2: ...de countries Recommended Standards used with EIA standards separator with ACO switched network backup test pattern check test pattern generate World Trade Fourth Edition Dec 1974 This is a reprint of...

Page 3: ...ure descrip tions Considerations in using the 3872 in World Trade countries are included in appropriate places in the manual and are summarized in Part 4 which also contains the Glossary This manual c...

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Page 5: ...Contents...

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Page 7: ...onnection Manual Operations on Non Switched Leased Line Modems Equalization Use of the Alternate Voice Feature 1 7 1 7 1 8 1 8 1 9 1 9 1 9 1 10 1 10 1 11 1 11 1 11 2 5 2 6 2 7 2 8 2 8 2 8 2 8 2 8 2 8...

Page 8: ...rocessing System 1 1 3872 Rear Panel 3 11 1 2 Equalizer Location by Configuration 1 2 3 7 Special Feature Characteristics and Qualifications 3 14 1 3 Modem Feature Configurations 1 3 3 8 Feature Outli...

Page 9: ...Part 1 General Information...

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Page 11: ...when transmitting When receiving it retrieves data from the chan nel signals and converts the data back to serial binary form DESIGN FEATURES The 3872 has an internal pseudo random bit pattern gener a...

Page 12: ...network operation with automatic answering Switched network operation of a modem configured for dedicated channel operation Automatic answering when operating on switched network backup Automatic pro...

Page 13: ...choice of communications service and modem configura tion 4 Peak volume of data This data system characteristic like the conversational mode of communication may be more indicative of processor needs...

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Page 15: ...band spectrum for simultaneous bidirectional transmission of signals can operate with half duplex facilities carrier can be transmitted in only one direction at a time Introduction to Modems Note When...

Page 16: ...channels or equivalent one for trans missions from the control station and one for trans missions to the control station The control station modem transmitter sends carrier continuously keeping tribut...

Page 17: ...f duplex service may be requested Multipoint terminal equipment requires four wire duplex service for satisfactory operation Switched Network USA and Canada Access to the public switched network requi...

Page 18: ...3 Tributary Station Transmit Line ___ I l C ontrol Station Transmit Line Figure 1 6 Centralized Multipoint Configuration A call is dialed and answered manually by DTE operators Modem communication is...

Page 19: ...nt timing 3 When all received data has been presented to the DTE and the modem no longer senses carrier it drops data carrier detected 4 The control station DTE if equipped to control the new sync lin...

Page 20: ...cradle the handset to disconnect Automatic access arrangements require a Not Ready condition from the DTE to discon nect Switched Network Manual Call Automatic Answer Sequences See Special Feature Des...

Page 21: ...n 3872 Test 1 Modem Test Concepts C In a half duplex configuration using the locally generated test pattern transmit to the remote station and have the pattern checked there local 3872 Test 3 remote 3...

Page 22: ...e receiver the modem momentarily turns off the Operate indicator Note 2 Tests illustrated here are lettered to correspond with those described and lettered under Modem Test Concepts in Port I of this...

Page 23: ...Part 2 Operator Information...

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Page 25: ...DATA 5 Equalizer switch es at optimum setting s See IBM 3872 Modem Problem Determination GA27 3062 Switched Network without ACO 1 Power switch set to ON 2 Test Operate switch set to OPERATE 3 Speed S...

Page 26: ...ator blinks on and off 1 when the modem receives the call signal l d and is off when the TEST OPERATE switch S is set on VOICE i OPERATE Indicator Shows that power is on When the TEST OPERATE switch i...

Page 27: ...the switch in this position will be discon nected if the switch is moved to another position HOOK CUT NEXT THROUGH DIGIT CHANNEL READY VOLUME Switch Th is continuous control turns on the Ca11 Progres...

Page 28: ...tched Leased Line Modems CJIQl 000 00 D 00 A 3872 Modem single or dual with this front panel is a point to point non switched leased line modem A 3872 Modem single or dual with this front is a multipo...

Page 29: ...nswering procedure In all procedures it is assumed that the calling station will transmit first Note The handset referred to in the following pro cedures is the handset of the DAA telephone The ex clu...

Page 30: ...tor to go to data mode Ifyou hear the answer tone wait for it to end and go promptly to data mode set the 3872 Talk Data switch to DATA and cradle the handset If you do not hear the answer tone hang u...

Page 31: ...hear the answer tone wait for it to end and go promptly to data mode pull up the data key and set the 3872 Talk Data switch to DATA Leave the handset out of the cradle If you do not hear the answer to...

Page 32: ...2 8 IBM 3872 Modem User s Guide To Make a Call 1 Plug the telephone handset cord into the VOICE jack on the front panel of the 3872 Modem 2 Set the Test Operate switch to VOICE between OPERATE and T4...

Page 33: ...Part 3 Technical Description...

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Page 35: ...ified by the grade of conditioning when arrangements are made for Modem Environment the channel For example the 3872 requires a type 3002 channel with C1 conditioning Equalizers Modem equalizers can c...

Page 36: ...send the IBM 3872 Modem configured for half duplex operation Figure 1 5 holds data carrier detected and received data off This action is known as clamping Request to send must be turned off when the D...

Page 37: ...wer cord ground wires should be connected together through earth or building ground Ring indicator Calling indicator A modem in a switched network configuration raises turns on ring indicator to the D...

Page 38: ...EIA Designation and Name l AA Protective Ground 2 BA Transmitted Data 3 BB Received Data 4 CA Request to Send 5 CB Clear to Send 6 cc Data Set Ready 7 AB Signal Ground 8 CF Data Carrier Detected ll S...

Page 39: ...ATA SET READY 25 DAA SWITCH HOOK SH g G m COUPLER CUT THROUGH CCT t RING INDICATOR RI DATA COMMUNICATIONS EQUIPMENT DATA TERMINAL EQUIPMENT DAA DATA TIP DATA RING RING INDICATOR Rll SWITCH HOOK SHI MO...

Page 40: ...position or when the test interface line is up on the 3872 turns on raises data set ready This is an exception to EIA RS 232 C Data Signal Rate Selector Line This line from the DTE to the modem contr...

Page 41: ...s or on the switched network The echo clamp at the formerly transmitting modem is shorter than the clear to send delay at the newly transmitting modem Note The switching of the data carier detected in...

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Page 43: ...andard racks Inches 12 12 8 8 Centimeters 30 5 30 5 20 4 20 4 Weight maximum 57 lbs 26 kg Heat Output 185 Btu hr 46 6 kcal hr Air Flow Natural convection only A clearance of at least 2 inches 5 08 cm...

Page 44: ...type 3002 channel with C1 conditioning In addition the characteristics of the required channel include those specified in the Bell System administrative guidelines as described in Bell System Data Com...

Page 45: ...000 0000000000 00 25 24 23 22 21 20 19 18 17 16 15 14 l lData T p DTi Data Ring DR I J3 Coupler Cut Through CCT J2 or J4 receptacle view Cable to CBS Data Coupler provided with 3872 OH DT 1 Dual 1 LL...

Page 46: ...scribed here 3 12 IBM 3872 Modem User s Guide Dialing signals ACO pulse mode consult the common carrier about applicability Automatic Call Delay strapping provides options of 20 40 or 60 seconds for a...

Page 47: ...by the modem when it automatically answers an incoming call Ring indicator The DAA raises turns on this line to the modem during the time the ringing signal is present on the line Switch hook The DAA...

Page 48: ...re programmed by DTE Includes automatic answering and 3 5 second 2100 Hz answer tone Line isolation transformer one for 2 wire two for 4 wire modem Visual and audible signaling and voice communication...

Page 49: ...n a Many interface Iines are not shown on this diagram See Figure 3 2 r Line Access Interface Dato Tip Dato Ring r _ Ring Indicator _ b Item 2 AA on o switched network 3872 is o special feature only w...

Page 50: ...INDICATOR RI DATA COMMUNICATIONS EQUIPMENT DATA TERMINAL EQUIPMENT DAA DATA TIP DATA RING RING INDICATOR RI SWITCH HOOK ISH IJ COUPLER THROUGH CCTJ DATA COUPLER CBS MODEM TRANSMIT DATA RE EDATA SIGNA...

Page 51: ...cation capability Calls are made or answered manually With this feature switched network service must be obtained from the common carrier including an access arrangement with a telephone set in additi...

Page 52: ...mally up on this line is dropped by the ACO feature during dial pulsing Data 3 18 IBM 3872 Modem User s Guide modem ready is raised again in expectation of an an swer tone from the called station This...

Page 53: ...send can be raised by the DTE DIRECT LINE ATTACHMENT FEATURE WORLD TRADE COUNTRIES This feature provides a transformer for each channel con nected to the modem Two wire modems require one trans forme...

Page 54: ...r 60 second answer time allowance Note DTE interface actions are in capital letters and underlined Digit Rises Must be up Drops Is up Call Is down Is down Must be up RAISE MUST DROP MUST DROP Invalid...

Page 55: ..._ 14 Generate answer become ready tone Drop ca 11 request raise request to send Become not busy Drop digit request remain off hook generate equalization signals if I _ Equalize DTE synchr nize Delay c...

Page 56: ...I Transmitter I _____ __ __ Mouthpiece Common Note Refer to the manufacture s instructions for the color coding of connecting wires Figure 3 13 Handset Plug Connections 3 22 IBM 3872 Modem User s Guid...

Page 57: ...DTE DTE FlG DTE B Multipoint_ Terminals over a Duplex Multipoint Network Control Station Controller 1 DTE Controller 2 DTE F 3872 Caution Request to send and data terminal ready must be dropped by the...

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Page 59: ...Part 4 Appendixes...

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Page 61: ...rld Trade Considerations DTE Interface The 3872 to DTE interface is the conventional DTE interface described in Part 3 however data terminal ready must be controlled for switched network mode The disc...

Page 62: ...answer is expected the Talk Data switch should be set to TALK if a data connection is expected the switch should be set to DATA 2 At the called station calling indicator rises for 225ms If the Talk D...

Page 63: ...iceband spectrum for simultaneous transmission of signals in both directions can operate with half duplex facilities carrier can be transmitted in only one direction at a time Appendix B Glossary Note...

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Page 65: ...Backup with BTAM The DTE business machine programming and equipment options for interface to the 3872 Modem are affected by planning for SNBU Operation Dedicated channel operation is likely to be mult...

Page 66: ...ng on the standby facilities programming for dedicated channels may be used with SNBU for point to point channels Automatic answering and disconnecting at the multiplexer requires control of the data...

Page 67: ...up Modems Legend __ Normal ____ SNBU Multipoint Programming 2701 2703 Multi lexer reduced polling 1ist for SNBU Point to Point Progra ming Line is redefined as a switched network line if there is auto...

Page 68: ...tation see Standby Config uration Planning previously discussed may require certain changes in equipment and programming to prepare for an SNBU operation Aside from these changes connecting and discon...

Page 69: ...recognition of the end of data transfer or by a separate telephone call the operators agree to disconnect 2 CPU operator closes the line in the program and cradles hangs up the telephone attached to...

Page 70: ...g the 3872 Modem for SNBU operation requires setting both 3872 Modems to 2400 SWITCHED or both 3872 Modems to 1200 SWITCHED The polling list at the CPU should be reduced to one terminal or up to three...

Page 71: ...Index...

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Page 73: ...ee GA27 3062 Fan Out feature 3 19 feature characteristics 3 14 restrictions 1 3 3 14 3 20 C 1 four wire see two wire four wire front panel 1 2 2 2 2 3 function DTE 1 5 modem 1 1 1 5 glossary of terms...

Page 74: ...ckup with Automatic Answering 3 17 specifications IBM 3872 Modem 3 6 3 9 communications channel 3 10 A 1 spurious space bits 3 4 3 6 standards interface CCITT Recommendation V 24 3 1 3 3 RS 232 C 3 1...

Page 75: ...esentative or the IBM Branch Office serving your locality Possible topics for comment are Clarity Accuracy Completeness Organization 11 dex Figures Examples Legibility READER S COMMENT FORM What is yo...

Page 76: ...s Reply Mail No postage stamp necessary if mailed in the U S A Postage will be paid by International Business Machines Corporation Dept E01 P O Box 12195 Research Triangle Park North Carolina 27709 In...

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