ATT System 25 Reference Manual
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FUNCTIONAL DESCRIPTION DATA TERMINAL EQUIPMENT,RS-232C HOST C0MPUTER SINGLE-LINEVOICE TERMINAL Z3A1/2/4ADU (2500-SERIES 7101A OR 7102A) DATA TERMINAL EQUIPMENT,RS-232CTN726DATA LINE CPHOST COMPUTERZ3A5ADU MULTILINEVOICE TERMINAL (7300H-TYPE) ATL CORDEDAND CORDLESS TELEPHONES CO, FX, WATS______ PAGING EQUIPMENT DID TRUNKS TIE TRUNKS T1 CARRIER PART OF DIGITAL SWITCH TN726DATA LINE CP TN724 ANALOG LINE CP ORZTN78 TIP RING LINE CP ZTN79 ATL LINE CP ZTN76 GROUND STARTTRUNK CPOR ZTN77LOOP START TRUNK CP TN753 DID TRUNK CP TN7608 TIETRUNK CP TN767DS1 INTERFACE CP TIMEDIVISIONMULTIPLEX BUS LEGEND: ADU – ASYNCHRONOUS DATA UNIT CAS– CALL ACCOUNTING SYSTEM CO– CENTRAL OFFICE CP – CIRCUIT PACK DID– DIRECT INWARD DIALINGDTU– DIGITAL TAPE UNITFX – FOREIGN EXCHANGE MET– MULTIBUTTON ELECTRONIC TELEPHONE OPS – OFF-PREMISES STATION SAT– SYSTEM ADMINISTRATION TERMINALSMDR– STATION MESSAGE DETAIL RECORDINGWATS– WIDE AREA TELECOMMUNICATIONS SERVICE Figure 3-5. Equipment Connections Via Circuit Pack Ports (Sheet 1 of 3) 3-10November 1995
FUNCTIONAL DESCRIPTION SAT, DTU, SMDR, CAS (ON-PREMISES) (DIRECT CONNECTION) Z3A1ADU*Z3A4 ADU * * REQUIRED FOR CONNECTIONS >50 FEET OR NOT SHARING SAME AC OUTLET SAT, SMDR,CAS (ON-PREMISESSWITCHED CONNECTION) Z3A1/4ADU Z3A4ADU TN726 DATA LINE CP SAT, SMDR,CAS (OFF-PREMISES DIRECT CONNECTION) MODEM(212-TYPE)COMODEM(212-TYPE) SAT, SMDR,CASE (OFF-PREMISESSWITCHED CONNECTION)†OPSTN742 ANALOG LINE CP MODEM(212-TYPE)COOR CO † OFF-PREMISES STATION OR CO TRUNK Z3A4ADU PART OF DIGITAL SWITCH ZTN142 CPU/MEM CP(1) SAT (2) SMDR, CAS (3) DTU (4) RESERVED TN726 DATA LINE CP ZTN142 CPU/MEM CP TIMEDIVISIONZTN142MULTIPLEXCPU/MEM CP BUS ZTN76GROUND STARTTRUNK CP ORZTN77LOOP START TRUNK CP TN726DATA LINE CP ZTN142 CPU/MEM CP Figure 3-5. Equipment Connections Via Circuit Pack Ports (Sheet 2 of 3) November 19953-11
FUNCTIONAL DESCRIPTION SINGLE-LINE VOICE TERMINALS (42, 500, 2500-SERIES, 7101A, 7102A) —————————— RECORDED ANNOUNCEMENTS —————————— DICTATION EQUIPMENT —————————— EXTERNAL ALERTING DEVICES —————————— MUSIC-ON-HOLD MULTILINE TERMINALS (7300H-TYPE ——————————DIRECT TRUNK ATTENDANT CONSOLE OR SWITCHED LOOP ATTENDANT CONSOLE ——————————ATTENDANT DIRECT EXTENSION SELECTOR CONSOLE (MODEL 23A1) ——————————ATL CORDED AND CORDLESS TELEPHONES MET SETS DICTATION EQUIPMENT—————————— PAGING EQUIPMENT (PagePac) NETWORK EXTENSION UNIT Figure 3-5. Equipment Connections PART OF DIGITAL SWITCH ZTN78 TIP RING LINE CP OR TN742 ANALOG LINE CP ZTN79 ATL LINE CP TIME DIVISION MULTIPLEX BUS TN735 MET LINE CP TN763 AUXILIARY TRUNK CP ZTN84 STARLAN INTERFACE CP Via Circuit Pack Ports (Sheet 3 of 3) 3-12November 1995
FUNCTIONAL DESCRIPTION The SAKI also does the following functions: — — — — — — — Identifies the circuit pack to the Common Control (location and vintage) Controls status indicator Light-Emitting Diodes (LEDs) — red (failure), green (translated), and yellow (circuit busy) Initiates power-on startup procedures Checks the on-board microprocessor for sanity and causes reinitialization in case of problems Takes NPEs out of service under control of the on-board microprocessor Resets the protocol handler on the ATL Line Circuit Pack Takes the whole circuit pack out of service on command from the Common Control or when it determines that on-board interference is present in the control time slots. TDM BUS LEADS CIRCUIT PACK ADDRESS LEADS ON-BOARDSAKIMICRO-PROCESSOR PORT SPECIFIC CIRCUITRY Figure 3-6.Port Circuit Pack Common Circuitry 3-13
FUNCTIONAL DESCRIPTION l NPE (Network Processing Element) Each port circuit pack contains one or two NPEs. The Analog Line, ATL Line, Tip Ring, Data Line, Ground Start, Loop Start, and DID Trunk Circuit Packs contain two NPEs. The MET Line, Auxiliary Trunk, and Tie Trunk Circuit Packs contain one NPE. The NPEs do switching network functions for the port circuits. Under control of the on-board microprocessor, an NPE can connect a port circuit to any one of the TDM bus time slots. More specifically, it allows a port circuit to talk on one time slot and listen to the same time slot (NPE sidetone) and on up to four other time slots at the same time. In 2-wire circuits that provide their own sidetone, the NPE sidetone is not used. l Circuit Pack Address Leads Seven leads (BA0-BA6) are tied to corresponding logic levels to uniquely identify each CP slot in the system, including multiple cabinet system. The logic values on leads BA4 and BA5 are used to identify the cabinet (Cabinet 1, 2, or 3) and are tied via the cabinet address plugs to either +5 V dc or ground, as appropriate. Lead BA6 is tied to ground. Analog Line (TN742) The Analog Line CP (Figure 3-7) interfaces eight analog voice terminal lines and the TDM bus. The TN742 can be used instead of the ZTN78 Tip Ring CP. The TN742 supports up to five bridged single-line voice terminals, but only two can be off hook at one time. The ZTN78 CP does not support bridged terminals.In addition, the TN742 supports out-of-building, extended, and off-premises stations, the ZTN78 does not. The Analog Line has the following unique circuitry: l Ringing Application Circuit This circuit receives ringing voltage from the power supply. It monitors ringing voltage and current, generates signals to the on-board microprocessor indicating zero ringing voltage and current, and detects a terminal user lifting the receiver during ringing.This prevents the application of ringing to the port circuit when a terminal user lifts the receiver during the ringing phase.Maintenance circuitry is also included. The maintenance circuitry detects when a terminal is connected to the port circuitry and checks for faults in the ringing application circuitry. l Port I/O Circuit This circuit consists of bus expanders connecting the on-board microprocessor and the port circuits.It receives commands from the on-board microprocessor and distributes them to the individual port circuits.It also accesses the port circuit scan points and passes the information to the on-board microprocessor. 3-14
FUNCTIONAL DESCRIPTION Figure 3-7. Analog Line (TN742) Unique Circuitry l Port Circuits The eight port circuits are identical. Each port circuit consists of a coder/decoder (codec), hybrid circuit, electronic battery feed circuit, ring relay, and overvoltage surge protection circuit. The codec is a 4-wire circuit that converts the analog signal from a voice terminal to a PCM data signal. It converts an incoming PCM data signal from the NPEs to an analog signal. The hybrid circuit converts the 4-wire analog signal from the codec to a 2-wire analog signal that is connected to the analog line. Filtered power is provided for the codec and hybrid circuits. November 19953-15
FUNCTIONAL DESCRIPTION The electronic battery feed circuit provides talking battery to the voice terminal. It also produces a controlled dc battery feed for short and long loops, detects when a receiver is lifted, and provides the message waiting signal by periodically turning off the feed voltage. The ring relay provides the interface between the ringing application circuit and the port circuit. It causes ringing turn on and turn off. The overvoltage surge protection circuit provides lightning surge and power line cross- protection for the circuit pack. ATL Line (ZTN79) The ATL Line CP (Figure 3-8) interfaces eight ATL voice terminals corded and/or cordless (7300H series) lines and the TDM bus. It terminates three pairs of wires from each terminal: analog voice pair, digital control pair, and power pair. The ATL Line has the following unique circuitry: l Protocol Handler The 8-bit on-board microprocessor translates the control information in Control Channel Message Set (CCMS) message format to the control information message format used by the 7300H series voice terminals. The protocol handler sends the messages to the terminals via transceivers located in the port circuits. l Port Circuits Each port circuit is identical. A port circuit consists of an analog port, one-half of a transceiver, and an electronic power feed device. The analog port circuit consists of a codec, a hybrid circuit, an isolation transformer, and associated power filtering circuitry. The codec and hybrid circuit perform the same function as the codec and hybrid circuit in the Analog Line Circuit Pack (TN742). The output of the hybrid circuit is connected to the primary of the isolation transformer. The secondary of the transformer is connected to the analog voice pair. The transceiver interfaces the voice terminal pair to the protocol handler. The electronic power feed device provides -48 volts dc on the power pair to the voice terminal. The device is polled by the on-board microprocessor, periodically and on demand, to test for an overcurrent or no-current condition. Each Electronic Power Feed (EPF) circuit supports two ports. If one of the associated lines becomes overloaded, the associated pair of lines will also be out of service. One EPF supports Ports 0 and 1, one Ports 2 and 3, one Ports 4 and 5, and one Ports 6 and 7. The on/off state of the device is controlled by the on-board microprocessor. 3-16November 1995
FUNCTIONAL DESCRIPTION TOMULTILINEVOICETERMINALSAND ATL CORDED AND CORDLESS TELEPHONES Figure 3-8.ATL Line (ZTN79) Unique Circuitry 3-17
FUNCTIONAL DESCRIPTION Auxiliary Trunk (TN763) The Auxiliary Trunk Circuit Pack (Figure 3-9) interfaces four ports provided for customer- provided equipment (CPE) and the TDM bus.It is connected to the CPE by up to three pairs of wires. The transmission pair (T and R) carry voice signals and touch-tone control signals. The T and R also provide a loop start seizure indication to the CPE. The seizure pair (SZ and SZ1) provide seizure indication to the CPE. The signal pair (S and S1) provide answer supervision and/or make-busy information from the CPE. Depending on the application, either the transmission pair only or all three pairs are connected to the CPE. The Auxiliary Trunk has the following unique circuitry: l Ground Detector Circuit This circuit determines if an answer-supervision or make-busy signal from the CPE is present. The inputs of the ground detector come from the port circuits as an analog current to the -48 volt dc supply. Its output is a port control point to the port I/O circuit. l Port I/O Circuit This circuit consists of bus expanders for communication between the on-board microprocessor and the port circuits.It receives commands from the on-board microprocessor and distributes them to the individual port circuits. It also accesses the port circuit scan points and passes the information to the on-board microprocessor. l Port Circuits The four port circuits are identical.Each port circuit consists of a codec, hybrid circuit, line transformer, relay driver, battery polarity sensor, and surge protection circuit. The codec is a 4-wire circuit that converts the analog signal from the CPE to a PCM data signal.It converts an incoming PCM data signal from the NPE to an analog signal. The hybrid circuit converts the 4-wire analog signal from the codec to a 2- wire analog signal that is connected to the CPE by a line transformer. The relay driver buffers and inverts the relay drive signals from the port I/O circuit so that a logic high input operates the appropriate relay. The relays control circuitry that provide the proper interfaces for CPE. The surge protection circuit provides lightning surge protection for the circuit pack. The circuit pack supports both touch-tone and dial pulse signaling. Longitudinal surges are isolated from the hybrid and codec by the line transformer. 3-18
FUNCTIONAL DESCRIPTION ON-BOARD MICROPROCESSOR TOAUXILIARY EQUIPMENT Figure 3-9.Auxiliary Trunk (TN763) Unique Circuitry Data Line (TN726) The Data Line Circuit Pack (Figure 3-10) interfaces eight Asynchronous Data Units (ADUs) data devices and the TDM bus. The ADUs are typically, in turn, connected to RS-232 type devices. The Data Line has the following unique circuitry: l Bit Clock The bit clock circuitry is used to provide the Octal Asynchronous Terminal Mode Two EIA Asynchronous LSIs (OATMEALs) with a clock frequency that is a multiple of each baud rate. In addition, the clock rate is divided down to 160 kHz. The 160 kHz is then compared to the 160 kHz system data clock and is phase-locked to it. The phase-locked circuit is required for low speed operation. l Bus Isolation This portion of the circuit pack is used to isolate the microprocessor bus. Isolation is required because the realized bus load exceeds the maximum limit specified for this device, due to the large number of devices controlled by the NPE. The OATMEALs are isolated from the common bus structure. 3-19