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IBM 3874, User Manual, Page: 56 / 88

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Summary of Contents for 3874

Page 1: ...Systems GA33 0002 3 TP 09 IBM 3874 Modem User s Guide...

Page 2: ...added and Appendix C removed These sections should therefore be read in their entirety Elsewhere changes to the text and or illustrations are indicated by a vertical line to the left of the change Ch...

Page 3: ...and glossary that explains terms used in the manual Differences as a result of national require ments between 3874 modems are summarized Describes equipment and programming considerations for back up...

Page 4: ...of Data Transfer 12 DAA CBS Used DAA CDT Used 15 Modem Tests 16 Overheating 16 Tests by Operator 16 Problem Determination 17 Procedure I Point to Point 18 Procedure II Multipoint All or more than one...

Page 5: ...44 Dimensions 44 Service Clearances 44 Weight 45 Heat Dissipation 45 External Power Supplies 45 Environmental Requirements 45 Connector and Cable Locations 45 Data Terminal Equipment Connector Basic...

Page 6: ...line point to point 12 Canada 57 9 Equalization in non switched line centralized 35 Telephone handset connection for Alternate Voice multipoint 13 feature 58 10 Equalization in switched network 14 36...

Page 7: ...Part 1 General Information D Part 2 Operator s Information Part 3 Technical Description Part 4 Appendixes D vii...

Page 8: ...Note All the controls shown cannot be present at the same time on a given 3874 as some of the features are mutually exclusive Frontispiece IBM 3874 Modem 18818 viii...

Page 9: ...rt 1 General Information I This part of the manual introduces the IBM 3874 Modem its highlights and its possible configurations a more technical description is given in Part 3 Part 1 General Informati...

Page 10: ...example when station A see Figure 1 sends data to station B modem A modulates the data and sends the modulated signal over the telephone line Modem B receives the modulated signal from the telephone l...

Page 11: ...switched line to a switched network if non switched line operation becomes impractical and to operate at 4800 bps on the Manufactured by American Telephone and Telegraph Company switched network in U...

Page 12: ...ature Decision Point to Point Multipoint Tributary Multipoint Control Switched Network with DAA Type CBS and Auto Answer Figure 2 Required and optio al features 1162SB 4 3874 User s Guide CBS Automati...

Page 13: ...ow the operator or DTE if this switch is set to EXTERNAL to select the switched network 2 DTE interface is modified 3 Additional telephone line interfaces are provided for connection to the DAA CBS or...

Page 14: ......

Page 15: ...Pa rt 2 0 pera to r s Inform ati on This part of the manual is intended for operators using the IBM 3874 Modem OPERATE TEST SWITCH The eight position operate test rotary switch is set to OPERATE for...

Page 16: ...LUME OFF EON 0 b02 0 00 04 O o LAMP TEST o PAUSE o M E A L l f SEP 0 90 05 OoO ENTER 8 7 6 Funct on Sw tch VOLUME Switch Manual Dialing Switches When this switch is set to OPERATE the ACO is controlle...

Page 17: ...the setting of the operate test switch Speed Mode Select Switch Must be set the same as other modems on the same line 4800 NON SW setting is for 4800 bps dedicated channel 2400 NON SW setti g is for...

Page 18: ...data transfer When the talk data switch is initially set to TALK an incoming call will sound the ringer of the telephone set associated with the DAA and the call must be answered manually Subsequentl...

Page 19: ...set Yes The involved station initiates an equalization procedure For local station in T1 A T1 Band T2 For local and remote station in OPERATE or T3 Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes If previousl...

Page 20: ...atically whenever The operate testswitch is set to OPERATE The speed mode select switch is set to4800 NON SW 2400 NON SW or EXTERNAL Power is switched on Note For switched rietwork applications see th...

Page 21: ...s successful Data set ready remains off Retry at least twice If Data set ready rises Ready for data communicat ion Use reset switch to retry equalization Equal indicator turns off 9s of equalization...

Page 22: ...I_ J 9s of equalization 1Bs of equalization No Yes after 18s Yes after 18 s Local and remote equalization successful L ocal equalization successful Data set ready remains off No Data set ready rises Y...

Page 23: ...t a Multipoint Tributary Station 1 Press the reset switch Equalization of the tributary station provided that it has been previously equalized by the control station and that the control station is ac...

Page 24: ...witch back to OPERATE b Wait for at least 10 seconds c Switch back to OPERATE on your 3874 Multipoint a Tributary station s switch back to OPERATE b Control station switches back to OPERATE with no de...

Page 25: ...tion Voice Exclusion Key CAUTION CBS Data When going to data mode handset cradled ensure that the handset is placed correctly horizontal on the cradle Never depress the cradle button with the finger W...

Page 26: ...espectively Both possibilities are considered in the following table II CBS_ CBS Operator Action Indicator On Audible Signal 1 Make the DTE ready Ready 2 Set the talk data switch to TALK 3 Remove the...

Page 27: ...both ends IJ CDT CDT Operator Action 1 Make the DTE ready 2 On the 3874 set the talk data switch to TALK 3 Raise the handset and dial the desired station 4 5 Voice communication to arrange transmit r...

Page 28: ...ta communication is complete the operator disables the terminal or sets the 3874 to TALK Auto Answering CBS only To have incoming calls answered automatically set the 3874 and prepare the DAA CBS as f...

Page 29: ...ering with CBS but with CDT at the other end Im cnT CBS Operator Action 1 Talk data switch was previously set to TALK 2 Lift the telephone handset 3 Pull the exclusion key on the telephone set 4 Voice...

Page 30: ...with CBS at the other end mCBS CDT Operator Action 1 2 Set the talk data switch to TALK 3 Lift the telephone handset 4 Voice communication with the calling operator to arrange transmit receive Note I...

Page 31: ...ss ENTER until present next digit indicator goes off 9 Release ENTER and wait for ringback tone 10 Dialing complete 11 12 Answer tone ends 13 14 15 Ready for data communication COMPLETION OF DATA TRAN...

Page 32: ...modem and one of the tributary modems never between tributaries Tests A B and E may be carried out for public switched network operation Test B however requires program ming support in the attached D...

Page 33: ...2 a fault is indicated by the operate indicator on the receiving 3874 going out momentarily after the equalization period 9s for tests A C and D 18s for test E A flash rate of from one to two flashes...

Page 34: ...eed with Procedure I e If problem is in switched network back up only proceed with Procedure IV Figure 13 Selection of problem determination procedure 11653A 26 3874 User s Guide checking or testing p...

Page 35: ...al and Go to 5 equal indicators on Go to 3 Call modem A CE Call modem 8 CE Operate signal and 1 Continue traffic at 2400 bps 1 Contact PTT to check the equal indicators on 2 Contact PTT to check the l...

Page 36: ...ontact PTT to check the line between control and line between control and furthest tributary station I I control station on furthest tributary station 2 Go to 5 T3 Operate signal andj 3 Go to 5 equal...

Page 37: ...tributary on Yes Switch settings correspond Go to 2 Restart and continue traffic When control station is Free no more traffic with other tributaries Go to 4 1 Check program and restart 2 If problem re...

Page 38: ...800 SW T1A RESET 5 cEB 4800 SW T1A RESET 30 3874 User s Guide Expected Result Yes No Same at Switch settings correspond Switch settings do not both stations Go to 2 correspond correct the settings and...

Page 39: ...o 10 1 Con tact common carrier T 1 and equal to check the line T indicators at 2 Go to 8 R R station A permanently on 4800 SW 4800 SW T4 T3 RESET 9 Restart Operation 10 T2 RESET 11 T2 RESET If DTE can...

Page 40: ...rough indicator on 1 7 Dial tone at r 1 calling station 8 Dial tone at css telephone set 1 9 Present next digit indicator on 10 Dial the number of a nearby telephone that can Nearby telephone be heard...

Page 41: ...ocedure Ill 17 Set local talk data switch to DATA and cradle handset 18 Ringback tone at station A Busy tone at station A Ringback tone stops at station A Answer tone at station A Answer tone ends at...

Page 42: ......

Page 43: ...Description This part of the manual is intended for system and installation planning engineers who require a more detailed description of the IBM 3874 Modem than that given in Part 1 Part 3 Technical...

Page 44: ...e transmitted simultaneously in both directions Transmitters and receivers are permanently on IBM 3874 Modem Each receiver is held continuously synchronized by the remote transmitter Data transmission...

Page 45: ...Figure 15 Switched Network I BM 3874 Modem I BM 3874 Modem CBS T I I I I T n m e t t Receiver __J L__ Receiver Local Switched Network Remote 0 DTE Switched Network Back Up I BM 3874 Modem Transmitter...

Page 46: ...Ready Calling Indicator Received Data Received Line Signal Detector Receiver Signal Element Timing Switched Network Operation j Legend l Automatic Equalizer Figure 16 Block diagram of 3874 11661A 38 3...

Page 47: ...Memory to Store the equalization parameters for each tributary Tributary Modems 6 max T T R Figure 17 Automatic equalizer locations 11662AJ Then the equalization process starts for 9s in both directio...

Page 48: ...NCHRONIZATION Before data can be sent from one 3874 to another the receiver of the receiving modem has to be synchronized with the transmitter of the transmitting modem Once this synchronization is ac...

Page 49: ...Calling Indicator Ring Indicator Test t Protective Ground Signal Ground Legend DTE controls these lines ____ 3874 controls these lines Common lines t Test is not a CCITT standard __ When there is a di...

Page 50: ...e If a re equalization is initiated while request to send is on ready for sending Remains on at a control modem during the equalization Drops at a tributary modem during the equalization Remains on or...

Page 51: ...nal element timing Figure 23 The modem cannot use clocking signals generated by the DTE Sampling Times i On 11 11 11 r1 Receiver Signal Element Timing _J J L J L J t__ Off ItI I I I I I I Rece ved Dat...

Page 52: ...ta 2 Continues transmission until the data received just before data terminal ready going off has been transmitted 3 Causes the DAA CBS to go on hook and to disconnect the modem from the line 4 Drops...

Page 53: ...digit can be accepted Data Line Occupied Direction From ACO The ACO sends data line occupied in reply to call request if the line is occupied as indicated by Ring indicator on DAA CBS associated hands...

Page 54: ...t 2 signals are exchanged as follows 1 The DAA detects the ringing signal and sends RI to the 3874 2 If the DTE is ready the 3874 signals off hook OH to the DAA 3 As soon as the DAA is ready CCT on th...

Page 55: ...which is sent only to the DTE that issued request to send The 3874 ignores any signals on the transmitted data lines coming from DTEs that have not raised request to send With switched network operat...

Page 56: ...ns and at least three modems From the operational standpoint the configuration is the same as an equivalent configuration where each tributary station has its own modem Figure 26b does not represent a...

Page 57: ...11671I t 1 r 1 3874 F r 3874 F 3874 3874 F r 3874 DTE DTE DTE DTE DTE DTE DTE DTE DTE DTE Tributary Stations 1 2 3 Tributary Stations 1 2 3 4 5 6 7 To eliminate the synchronization delay when changin...

Page 58: ...dBm to 17 dBm in 1 dBm steps Mandatory in multi point control Optional in point to point can be used with fan out feature Control Station Prevents the control Reduces the equaliza station from pollin...

Page 59: ...earances Given in Figure 28 28 22 55 9 6 15 3 Figure 28 Service clearances 17914A Weight Maximum with All Features I lb 65 kg 29 5 Heat Dissipation BTU hour 600 max kcal hour 150 max External Power Su...

Page 60: ...ving and terminating circuits must meet CCITT recommendation V24 and or EIA standard RS 232 c Connector Identification DTE 3874 r I Telephone DAA I Line L ____ I J3 J4 J5 Pin Locations 13 12 11 10 9 8...

Page 61: ...Ground 13 Distant Station Connected 14 Digit Signal 1 15 Digit Signal 2 16 Digit Signal 4 17 Digit Signal 8 22 Data Line Occupied Figure 31 Data terminal equipment 3874 ACO interface 11676 DAA CBS CO...

Page 62: ...ound Green Yellow Countries Using 60 Hz Phase Neutral 3874 Length 6 ft 1 83m Line Cable Non Switched U S A or Canada 3874 11 ft 3 35 Cable entry is at rear of plug Length 10 ft 3 05m 15 ft 4 57m 20 ft...

Page 63: ...4 Length 10 ft 3 05m 15 ft 4 57m 20 ft 6 1Om 25 ft 7 62m Connection to DAA CBS 3874 J2 25 pin Plug Fixed to socket by knurled screws to permit quick release Length 10 ft 3 05m 15 ft 4 57m 20 ft 6 1Om...

Page 64: ...eive pair to BK and Y Japan Connection to a voice band private non switched Dl line is to be made via a four pin IBM provided socket to a PDlA 56 3874 User s Guide protective device The customer insta...

Page 65: ...lity CCITT recommendation M102 Consult your IBM representative to obtain information on specific procedures and facilities available in your country Permitted transmit power level and signal to noise...

Page 66: ...gs the correct plug being provided with the alternate voice feature The connections to the plug are shown in Figure 35 Ring I I __ Ring Sleeve Tip or Receiver Transmitter In some countries for example...

Page 67: ...Part 4 Appendixes Part 4 Appendixes 59...

Page 68: ...t 3 Switched Network feature and 1 See under Variations 3 Switched Network Back Up Available Not available in Part 1 for descriptions features 2 See Switched Network Setting Up the Line 17 in Part 2 f...

Page 69: ...available with all access methods see under Equipment Selection at CPU End for details of documentation available Planning a system that will accommodate switched network back up operation involves th...

Page 70: ...j 1 Switched Network c Two Modems Two Multiplexers One 3874 equipped with Point to Point or Multipoint Control feature One 3874 equipped with Switched Network feature Multiplexer 1 _ l Alternative Mul...

Page 71: ...uplex see Figure 15 The DTE must be permanently wired for half duplex control of the request to send interface line Where appropriate duplex throughput is maintained by strapping the 3874 for continuo...

Page 72: ...CAM Customer s Application 115 125 ICAs 270X 370X EP 270X 370X EP b BSC Operation with Half Duplex Data or SDLC Operation with Duplex Data CPU Operating System OS VS TCAM VTAM CPU 370X NCP 370X Operat...

Page 73: ...704 05 NCP Mode VTAM NCP Figure 41 Access methods communication controllers 20406 Equipment Selection at CPU End Planning the back up of links in a system environment requires a careful evaluation of...

Page 74: ...terminal that is normally on a multipoint non switched line requires use of multipoint procedure programming support 66 3874 User s Guide at the multiplexer with a polling or addressing list of one te...

Page 75: ...answering and disconnecting by controlling the data terminal ready interface line SNBU with DAA CDT 270X 370X EP Yes 1 115 125 ICA s Multiplexer 370X NCP BSC terminals except 2770 2780 3270 Yes 2770 2...

Page 76: ...e Manual call at CPU manual answer at terminal or remote 370X e Manual call at CPU auto answer at terminal or remote 370X e Auto disconnect at CPU manual disconnect at terminal e Manual or auto call a...

Page 77: ...erican National Standard Definition FCC Federal Communications Commissions Hz hertz cycle per second ICA kcal ms PTT s SNBU sync Integrated Communication Adapter kilocalorie millisecond Post Telegraph...

Page 78: ...equipment and a 70 3874 User s Guide modem see Figure 1 Strap Strapping Selectable wmng to provide optional variations in the performance of equipment Switched Line Switched Network A communication l...

Page 79: ...ous carrier 37 42 50 control characters 45 control circuit 38 control station problem determination 26 controls for operator 7 country differences 60 coupler cut through 46 customer responsibilities 5...

Page 80: ...3874 User s Guide indicator coupler cut through 8 data channel ready 8 data line occupied 8 equalization 9 off hook 8 operate 9 present next digit 8 ready 9 signal 9 interface K data access arrangemen...

Page 81: ...nterface 44 R ready for sending 42 received data 42 received line signal detector 43 receiver 38 receiver signal element timing 43 reception of data 38 remote wrap test non switched line 24 25 request...

Page 82: ...end to end non switched line 24 25 switched network 24 25 modem internal wrap 24 25 modem DTE wrap 24 25 remote wrap non switched line 24 25 74 3874 User s Guide test interface signal 44 test pattern...

Page 83: ...the IBM Branch Office serving your locality Possible topics for comment are Clarity Accuracy Completeness Organization Index Figures Examples Legibility What is your occupation ______________________...

Page 84: ...ions become the property of IBM Fold Fold 1 Fold Business Reply Mail No postage stamp necessary if mailed in the U S A Postage will be paid by International Business Machines Corporation Department 81...

Page 85: ...the subject publication Pages to be inserted and or removed are 29 through 32 Changes to the text or to an illustration are indicated by a vertical line to the left of the change Summary of Amendment...

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Page 88: ...es Ce rpc ratlon Dat11 P ocessfng l ivlsJon 1133 Westch ster Averif 1 V hit Plains New York 10eo4 U S only IBM world Trade Corporatie n a21 United N ations rs1aza New York New York 10 011 lnternatlo n...

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