Comdial Dxp Plus Instructions Manual

							7.7 Radio Frequency Interference
The electronic key system contains incidental radio frequency generating circuitry and, if not installed and used
properly, may cause interference to radio and television reception. This equipment has been tested and found to
comply with the limits for a Class A computing device pursuant to Subpart J of Part 15 of FCC Rules. These
limits are designed to provide reasonable protection against such interference when operated in a commercial
environment. Operation of this equipment in a residential area may cause interference to radio and television
reception; in which case the user is encouraged to take whatever measures may be required to correct the
interference.  If this equipment does cause interference to radio or television reception, which can be determined
by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the
following measures: Reorient the television or radio’s receiving antenna, and/or relocate the DXP, the individual
telephone stations, and the radio or TV with respect to each other. If necessary, the user should consult the
manufacturer or an experienced radio/television technician for additional suggestions.  The user may find the
following booklet prepared by the Federal Communications Commission helpful: “How to Identify and Resolve
Radio-TV Interference Problems.”  This booklet is available from the Government Printing Office, Washington
D.C. 20402. Stock No. 004-000-00345-4.
This equipment has been tested and found to comply with the limits of a Class A digital device, pursuant to Part
15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference
when the equipment is operated  in a commercial environment. This equipment generates, uses, and can radiate
radio  frequency energy and, if not installed and used in accordance with the instruction manual, may cause
harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause
harmful interference in which case the user will be required to correct the interference at his own expense.
This digital apparatus does not exceed the (Class A) limits for radio noise emissions from digital apparatus set out
in the Radio Interference Regulations of the Canadian Department of Communications.
Le pre’sent appareil nume’rique n’emet pes de bruits radioe’lectriques de’passant les limites applicables aux
appareils nume’riques (de la class A) prescrites dans le Re’glement sur le brouillage radioe’lectrique e’dicte’ par
le ministe’re des Communications du Canada.
CAUTION
Changes or modifications to this unit not expressly approved by the party responsible for compliance
could void the user’s authority to operate the equipment.
Installing The DXPT1 Line Board IMI89–193
Installing The DXPT1 Line Board – 31 
						

							7.0 Knowing The Specifications
DXP Capacity10 T1 boards
ModesSuperframe, extended superframe
FramingD4
Channels Allocated8, 16, or 24
Industry StandardsANSI T1.403-1989
AT&T PUB 62411
Maximum Output2.4V to 3.6V base to peak, short circuit
protection to 120 mA, rms
Line Rate1.544 Mbps
Line Code
Type Bipolar AMI
Zero Suppression B7 or B8ZS selectable
Receive Sensitivity-26 dB or -36 dB selectable
Impedance100 Ohms
DXP Loss Insertion
Transmit -6 dB (selectable to 0 and -3 dB per channel)
Receive 0 dB
T1 ConnectorRJ48C, miniature 8-position, shielded
(per ANSI T1-403, 1989)
T1 CableUp to 6,000 feet between DXPs, 22 AWG,
twisted-pair, no external components
CSU FunctionBuilt-in; CPE or CARRIER selectable (ESF)
Transmit Attenuation
Manual 0, -7.5, -15, or -22.5 dB selectable
Automatic Default
Input Jitter Tolerance138 UI @ 1 Hz; 0.4 UI @ 10 KHz—100 KHz
(0 dB line); corner frequency = 6 Hz (attenuates
20 dB per decade above corner)
Surge Protection1 AMP fuse and transient protection for metallic
>6 volts P-P; Longitudinal (tip—ring and chassis
ground) protection 1500 volts minimum.
Elastic StoreTwo frames, no frame loss when slipping
ComplianceFCC Part 68/Doc
FCC Part 15
UL-1489/CSA (safety):Yellow Alarm Type
Superframe Mode Bit 2 zero in all channels or Japanese 12th
frame method, selectable
Extended Superframe Mode Alternating bytes = all zeros and all ones;
(prohibiting ANSI FDL messaging during
yellow alarms is selectable)
Signaling
Signaling Protocols Loop Start (subscriber end)
Ground Start (subscriber end)
E& M
Direct Inward Dial (DID)
Dialing DTMF or Dial Pulse
Protocol Type (DID, E&M) Wink, Delay-Dial, and Immediate Start
(dial pulse only for immediate start)
DID Type Restriction Limited to four of five types when mixing
tone/dial pulse/wink/delay dial/immediate
start)
Clocking
Synchronization Slave mode from DXOPT-SYN card on
Auxiliary board
Min. RX Freq. Capture 1.544 MHz±200 Hz, T1 board;
16.384 MHz±2048 Hz, Sync card
TX Master Mode Freq. 1.544 MHz±75 Hz
Loopback Modes
Superframe Mode Local or remote loopback, manual
Network loopback inband command;
set 00001 5sec, reset 001 5 sec.
Extended Superframe Mode Local, remote, payload loopback (manual)
FDL ANSI network remote loopback
FDL ANSI network payload loopback
LED Alarms/ErrorsStatus
Red Alarm
Yellow Alarm
Blue Alarm
Loss of receive synchronization
Loss of signal
Bipolar error(s)
CRC errors (ESF)
Slip errors
Phase Lock error
Facilities Interface Code (FIC) 04DU9–1SN
IMI89–193 Installing The DXPT1 Line Board
32 – Installing The DXPT1 Line Board 
						

							8.0 Defining The T1 Terms
Bipolar
A bipolar signal is composed of alternating pulses that both represent a digital logic 1. The positive pulse is a (+)
and the negative pulse is a (-). Zero volts represents a space, or digital logic 0.
Bipolar Violation (or error)
A bipolar error is a digital logic 1 (or mark) that has the same polarity as its predecessor.
NOTE: Every time the system regenerates the signal stream, it corrects any bipolar errors; therefore, it prevents
end-to-end error checking from using bipolar errors.
B8ZS (Binary Eight Zero Substitution)
This is a technique to send an all-zero channel without violating the ones-density requirement (a single one in
each channel and no more than 15 zeros in a row). Voice transmission will not allow an all zero channel. The
system accomplishes B8ZS suppression by inserting a special bipolar error that is interpreted, not as an error, but
an all zero channel. The B8ZS feature replaces the all-zero channel two different ways. The feature replaces the
all-zero channel with the sequence 000 + - 0 - + if the preceding pulse was a +, and the feature replaces the
all-zero channel with the sequence 000 - + 0 + - if the preceding pulse was -. The + represents a positive pulse,
the - represents a negative pulse, and 0 represents no pulse. Set the B8ZS feature with switches SW1–5 and
SW1–6.
CAS (Channel Associated Signalling)
The Channel Associated Signalling is the only inbound signalling method currently supported by the DXPT1
board.
COFA (Change of Frame Alignment)
When switch SW2-6 is off, the green LED on the DXPT1 indicates whether the network source or the network
span caused the last frame synchronization. (This indication disregards the first re-sync at cold start or a system
reset —cold start and reset causes the network source to re-sync.) A COFA occurs if the network source does a
re-sync. The COFA is a diagnostic tool that identifies the source of the loss of frame synchronization.
CPE/Carrier Equipment
The DXPT1 is normally classified as Customer Premise Equipment (CPE). If you use SW2–2 to configure the
DXPT1 board to use the internal CSU while in the ESF mode, the network may require that the system be
classified as Carrier Equipment (CE). The information packet that the DXPT1 board sends to the network
contains a facility data link (FDL) maintenance message that has a bit in it that provides this identification.
CRC (Cyclic Redundancy Check)
A method of checking errors from the transmission source to the destination. For T1 operation, CRC caculates a
checksum depending on the data in a frame. The system uses CRC in ESF mode exclusively. (You must enable
CRC with DIP switch SW2-4).
Delay Dial E&M, DID Protocol Type
Once seized by a calling system, the system being called makes A=1 and B=1 until it is ready to receive digits.
When it is ready to receive digits, it makes A=0 and B=0. The system uses a delay dial protocol when wink
protocol timing is not compatible to the network.
Dial Pulse – T1
Dial pulse is a method of sending address digits (numbers) using A and B bits logic bits instead of sending DTMF
tones. Some carriers may not support dial-pulse signalling. While the method is slower when compared with
tones, it requires no DTMF receivers.
Installing The DXPT1 Line Board IMI89–193
Installing The DXPT1 Line Board – 33 
						

							Direct Inward Dial (DID) T1 Trunk
DID is a protocol for inbound calls where the network sends the extension number during the beginning of the
call. The system supports the 0 through 7 inbound digits. The network does not translate the digits to a valid
extension—the system’s DID translation tables perform this action.
DS-0 (Digital Signal-Level Zero)
Digital Signal-Level Zero is a single 64Kbit channel inside a T1 span.
E & M T1 Trunk
E&M is a signalling protocol that supports both inbound and outbound digits. Inbound digits from the network are
already translated to a 3–digit or 4–digit valid extension. E & M is symmetrical from both ends and ignores the
subscriber/office classification of other trunks. Use this signalling protocol for interconnecting two DXP Plus
systems.
Extended Superframe Mode (ESF)
Extended Superframe Mode consists of 24 frames. The frame bit uses only 6 frames leaving 18 bits for other
purposes. These spare 18 bits provide 6 bits for CRC information and 12 bits for a facility data link. The facility
data link is for maintenance information (as defined by the ANSI T1.403 specification). Like the superframe
mode, the 64–Kbit user channels have 24 frames available for use.
Ground Start T1 Trunks
Ground start is a call signalling protocol that monitors only outbound digits and supports disconnect supervision.
Ground start protocol supports only the subscriber end of the communications link
FDL (Facility Data Link)
The Facility Data Link is a 4–Kbit communication link from the network to the DXPT1 board only when the
board is operating in the ESF mode. The system sends preemptive messages (for example, yellow alarm and
loopback), if needed, and sends error packets to the network once a second. The packets contain alarm history in
accordance with the ANSI T1.403 specification.
Fractional T1
Fractional T1 is a T1 span where the user uses less than 24 channels. The DXPT1 board allocates eight or 16
channels to a fractional T1 but does not reallocate unused channels in the eight, 16, or 24 mode to other resources.
A fractional T1 in ESF mode will nullify the CRC and other error checking capability since the network shares
channels.
Immediate Start Protocol State
Once a calling system seizes a called system, the calling system sends address digits to the called system without
requiring an acknowledgement. Inbound immediate start protocol does not support tone dial. Dial-pulse is
adequate however. Immediate start protocol is applicable to DID and E&M tie lines.
Inband Signalling
A signalling method where the system sends overhead signalling along with channel traffic.
ISDN (Integrated Services Digital Network) Primary Rate (also called PRI)
Currently not offered by the DXPT1 board.
Loopback Local
An operation method that loops the DXPT1 board’s transmit output and receive input paths. The loopback
terminates all traffic and halts call processing. While in this idle condition, the system continues to transmit the T1
transmit stream to the network but it will not answer incoming calls. If the remote T1 equipment is the clock
source (primary or secondary) for the DXOPT-SYN card, the remote equipment terminates the reference signal
because the network receive circuit is open in local loopback. You initiate local loopback by setting the
appropriate SW1 switches. The main purpose of local loopback is to verify the DXPT1 board’s ability to
synchronize properly. Loopback local operation is applicable to superframe adn extended superframe modes.
IMI89–193 Installing The DXPT1 Line Board
34 – Installing The DXPT1 Line Board 
						

							Loopback Payload
The loopback payload feature is an ESF-only method of loopback which loops the network receive input path to
the remote T1 equipment’s transmit output path. This loopback method does not loop the first bit of each frame to
allow the DXPT1 board’s facility data link to continue to transmit maintenance information. You can use switches
SW2–7 and SW2–8 to manually initiate the payload loopback or you can allow the network to send an FDL
message to initiate or restore the payload loopback. The DXPT1 board goes out-of-service during the loopback
time.
Loopback Remote
The loopback remote feature loops the network receive input path to the remote T1 equipment’s transmit output
path.  The remote loopback feature terminates all traffic and halt any call processing. You can use the SW2
switches to manually initiate remote loopback or you can allow the network to remotely initiate the condition. In
superframe mode with SW2–1 set to on, the network can send a special in-band pattern
(00010001000100010001.... min 5 seconds) to cause the DXPT1 board to automatically enter the remote
loopback mode. The network can disable the loopback by sending a different in-band pattern
(001001001001001001001.... min 5 seconds). In ESF mode, the DXPT1 board’s facility data link, or maintenance
channel, can enable and disable remote loopback automatically or you can set SW2–7 on and SW2–8 off to
manually enable remote loopback or set both switches off to manually disable the feature. Loopback remote
operation is applicable to superframd and extended superframe modes.
LIU Line Interface Unit
The line interface unit is the interface between the T1 copper wires and the DXPT1 board’s framing circuitry.
The LIU is responsible for separating the 1.544MHZ receive clock from the incoming stream and converting
bipolar Alternate Mark Inversion (AMI) to 5–volt digital logic. The LIU also supports the automatic line build-out
that regulates the transmit level according to the receive strength (LIU-2 switch).
Loop Start T1 Trunk
Loop Start T1 Trunk is a network protocol that monitors outbound digits to the DXPT1 board. This protocol does
not support disconnect supervision. Loop start protocol supports the subscriber end of the communications path
but does not support the office (network) end.
Primary Clock Reference
The straps on the DXAUX board designate the primary clock reference. Primary clock reference is the first choice
reference clock used to synchronize the DXP Plus to the incoming span. If the system looses synchronization, it
uses its secondary clock reference. If the secondary clock reference is not available, the DXOPT-SYN card’s
variable clock oscillator (VCO) switches to the fixed oscillator on the DXSRV (services) board. When it does
this, slips occur.
Repeater
A repeater is a amplifying device that central office technicians place at approximately one mile intervals along a
T1 circuit to boost the T1 signal. The T1 specifications allow a maximum of 50 repeaters along a communications
path.
Slip
This term describes the condition that exists when the transmit 1.544 MHz clock is different from the receive
1.544 MHz clock. When the system collects or looses a frame of information due to the span frequencies being
different, the system generates a slip error. Slip does not affect voice transmissions and may not affect modem
traffic; however slip does effect digital data traffic. The DXPT1 board does not currently support digital data
traffic. Also, at times a central office takes a T1 span out of service if too many slips occur—one or two a day is
permissible (the carrier supplier will furnish you with an an exact number if you request that information from
them).
Installing The DXPT1 Line Board IMI89–193
Installing The DXPT1 Line Board – 35 
						

							Smart-Jack (Network Interface Box)
A smart jack is a demarcation box provided by the central office. A smart jack provides isolation and increased
signal drive (up to one mile) and can respond to loopback commands for diagnostic purposes. The central office
usually provides an 8–pin modular jack for T1 equipment connection. Pin 1 of the modular jack goes to pin 1 of
the DXPT1 modular jack, and so on. Only pins 1 and 2 (DXPT1 receive), 4 and 5 (DXPT1 transmit) require
connecting.
Superframe Mode (SF)
The standard T1 mode consists of 12 frames per superframe cycle. The first frame bit remains constant and
rotates through a 12-bit pattern.  By identifying the frame pattern, the system can select the sixth and twelfth
frame for the AB bit signalling inband method. T1 parameters allow for 24 64–Kbit user channels.
Suppression
Suppression is a means to prevent more than 15 zeros in a row and not less than 1 pulse (mark) per channel. The
DXPT1 board supports two suppression methods. These are the B7 method and the B8ZS method (selected by
SW1–5 and SW1–6). The B7 method inserts a logic 1 in the seventh bit position of a channel if all bits are zeros.
The B8ZS method inserts a bipolar violation that will be identified and stripped at the receiving end (selected by
switches SW1–5, and SW1–6). Voice coding should not allow an all zero channel.
Unlock Alarm
On a normally operating DXPT1 board, the unlock alarm LED is always off. If this LED is on, it indicates that
the phase lock loop creating the transmit 1.544 MHz frequency is defective. For this indicator to be meaningful,
the DXOPT-SYN card must be synchronized (no red LEDs on). If the DXOPT-SYN card is not synchronized,
you must correct that situation.
Wink E&M, DID Protocol State
This effect is a quick response by a called system (A=1, B=1) to a calling system that seized the line. The
response indicates that the called system is ready to receive address digits.
Yellow Alarm
The yellow alarm indicates that the network has lost its incoming frame synchronization. The DXPT1 board
signalling is inactive for approximately three to four seconds during this alarm time, and the system halts all call
processing. If the system clears the received yellow alarm within the time limit, the DXPT1 board’s inactive state
terminates and call processing continues.
The system sends a yellow alarm to the network if it loses incoming frame synchronization or if the DXPT1 loses
communications to the CPU board. Received and transmitted yellow alarms can not exist at the same time. If such
a situation occurs, the system inhibits the transmitted alarm.
ZBTSI (Zero Byte Time Slot Interchange)
Zero Byte Time Slot Interchange is a complex technique to insure that the T1 transmission meets the pulse density
requirement. This ZBTSI technique is unpopular in the telephone industy, and the DXPT1 board does not support
the feature.
Charlottesville, Virginia 22901-2829
R
World Wide Web:  http://www.comdial.com/
Accredited by the Dutch Council
for Certification for certification
and registration activities.
Comdials Quality Management System Is
Certified To The ISO 9001 Standard.
IMI89–193 Installing The DXPT1 Line Board 
						

							Installing The Serial Data Modem
In The DXP Plus Digital Communications System
1.1 Understanding The Modem
The serial data modem allows remote servicing and programming of the DXPPlusdigital communications
system. The DXMDM is a general-purpose, Hayes*-compatible, serial data modem that receives its operating
power and configuration programming from the DXP Plus. The modem’s operating parameters appear in the
following chart.
* Hayes is a registered trademark of Hayes Microcomputer Products
BPS Out BPS In Data Bits Stop Bits Parity Flow Control
2400 2400 8 1 None None
R
SERIAL
Status
PWR
Line
PLUS013
Power
Cord
Serial Port
Cord
Detailing The Serial Data Modem
This manual has been developed by Comdial Corporation (the “Company”) and is intended for the use of its customers and service personnel. The information in this manual is subject to change
without notice. While every effort has been made to eliminate errors, the Company disclaims liability for any difficulties arising from the interpretation of the information contained herein.
The information contained herein does not purport to cover all details or variations in equipment or to provide for every possible contingency to be met in connection with installation, operation, or
maintenance. Should further information be desired, or should particular problems arise which are not covered sufficiently for the purchaser’s purposes, contact Comdial, Inside Sales Department,
Charlottesville, Virginia 22906.
Printed in U.S.A.IMI89-185.01
7/95 
						

							1.2 Installing The DXMDM Modem
The following procedure explains how to install the serial data modem. Figure 1 illustrates the relative position of
the modem and the location of its connections. The modem fits on the left side of the equipment shelf.
1. Locate DIP switch SW7 on the services board, and set it to its OFF position.
2. Insert the modem as illustrated in Figure 1.
3. Attach the modem to the equipment shelf with a single screw through the mounting-screw hole on the
modem’s front plate.
4. Connect the PWR cable from the modem to the jack labeled Modem Power on the CPU board. The modem’s
STAT light should come on.
NOTE: The serial data modem comes from the factory with the PWR and serial port cables already installed.
They are purposefully difficult to remove; however, you can disconnect the cables for replacement if
necessary. To do so, reach into the opening and press the tab down to release the connector while you pull
the cable out from the jack.
5. Connect the serial port cable from the modem to the jack labeled Modem Com (serial data port) on the CPU
board. This is the default port for the modem. When you use this connection, you will not need to take any
programming action. Alternately, you can connect the modem to one of the serial data ports provided by the
communications card installed on the auxiliary board (if one is installed on your system). If you use a a serial
data port other than the default port, you must assign it for modem operation using the database programming
procedure.
6. Connect a telephone line into the modem’s line jack.
7. Set DIP switch SW7 to its ON position to ensure continuous modem operation. This step is necessary because
the serial data modem depends upon the DXP Plus for both its power and configuration. With switch SW7 set
ON, the system automatically matches the baud rate and serial data parameters of the modem regardless of
which port you choose for modem connection.
CAUTION
If you disconnect the modem PWR cord from the DXP Plus, you must reset the modem after you reconnect
the PWR cord. Set switch SW7 to OFF, wait five seconds, and then return it to ON to reset the modem.
(You can also reset the modem from the programming station. To do so, enter the system-manager
programming mode and then dial18#).
IMI89–185 Installing The Serial Data Modem
2 – Installing The Serial Data Modem 
						

							SERIALStatus
PWR
Line
Power
Cord
Serial Port
Cord
PLUS014
Telephne Line Cord
Figure 1. Installing The Modem In The Main Cabinet
Equipment Shelf Serial Port Cord
Power CordTelephone Line Jack
Modem
Power Jack
Default
Modem
Communications
Jack
DIP
Switches
CPU Board
PLUS015
Figure 2. Viewing Modem Position And Connection Locations
Installing The Serial Data Modem IMI89–185
Installing The Serial Data Modem – 3 
						

							Installing A Dual Tone Multiple Frequency (DTMF)
Receiver Card In The DXP Plus Digital Communications
System
1.0 Introducing The DTMF Receiver Card
The DXPPlusdigital communications system supports the use of on-premise industry-standard telephones.
To support the DTMF dialing of industry standard telephones, the DXP Plus services board provides on-board
DTMF receiver circuitry. This circuitry supports dialing of one industry-standard telephone at a time. This
provision is adequate, if your site requires only a few industry-standard telephones; however. if you intend to
support a population of industry-standard telephones that will generate a large volume of outgoing call traffic, you
must install one or more DTMF receiver cards to provide additional DTMF receivers for the telephones. Each
DXOPT–TON card allows four industry-standard telephones to dial simultaneously. The number of cards that you
need to install in the system depends upon how active the industry-standard telephones will be at the site. See
Section 1.1 for details.
If you do need to add receiver cards, you have three choices as to where to install them.
1. The best and recommended choice is to add one receiver card to top position on the main cabinet’s services
board.
NOTE: You can add two additional receiver cards to the lower two positions on the services board; however, you
must take specific programming action to enable their use (the name of this program option is: Services
DTMF Highway). If you add these two cards and take this program option, you can only add one card to
the lower expansion cabinet’s interface board (discussed in step 2 below).
2. The second best choice is to add up to three receiver cards to each expansion cabinet’s interface board if one
or both is available. Remember, add only one card to the lower expansion cabinet’s interface board if you
have added or will add two additional receiver cards to the lower two positions on the services board and take
programming action to enable their use
3. The third choice is to add an auxiliary board to the system and install up to four DTMF receiver cards on it.
This is the least desirable choice because it requires you to occupy a board slot that you could otherwise use
for line or station boards.
R
This manual has been developed by Comdial Corporation (the “Company”) and is intended for the use of its customers and service personnel. The information in this manual is subject to change
without notice. While every effort has been made to eliminate errors, the Company disclaims liability for any difficulties arising from the interpretation of the information contained herein.
The information contained herein does not purport to cover all details or variations in equipment or to provide for every possible contingency to be met in connection with installation, operation, or
maintenance. Should further information be desired, or should particular problems arise which are not covered sufficiently for the purchaser’s purposes, contact Comdial, Inside Sales Department,
Charlottesville, Virginia 22906.
Printed in U.S.A.IMI89-186.01
7/95