Comdial Dxp Plus Instructions Manual

							3.3 Wiring The Batteries
The charger has a pair of negative wires and a pair of positive wires(designated by red sleeving near one end of
the wires). This two-wire arrangement divides the current carrying load between the two wires of each pair. The
cabinet’s assembly package includes two individual black wires that you use to wire the circuit breaker to the
batteries. Again, two wires divide the current carrying load between both wires.
The negative wires from the charger are terminated with smaller size terminals than the those that terminate the
charger’s positive wires. Connect the smaller (negative) terminals to the circuit breaker and the larger (positive)
terminals to the positive battery post. The individual wires that you use to connect the circuit breaker to the
battery post are also terminated with a large terminal on one end and a small terminal on the other. Connect the
smaller terminals to the circuit breaker and the larger terminals to the negative battery post.
Wire the batteries as shown in the schematic. Use the supplied hardware to connect the wires to the batteries per
method shown in the detailed drawing.
Once you have wired the batteries, attach the front cover to the cabinet with the supplied hardware.
Two Black Wires With Red Sleeving
(Positive Lead)
Two Black Wires
(Negative Lead)
Two Black Wires
(Negative Lead)
Strap (Four Places)
Batteries ChargerCircuit BreakerPLUS005
- -
-
-
--+ +
+
+
++
Connecting The Wire Harness
IMI89–197 Installing The Switchable Battery Back Up Assembly
12 – Installing The Battery Back Up Assembly 
						

							#10-32 Machine Screw
Wire Terminal
Battery Terminal
Wire Terminal
#10 Flat Washer
#10 Lockwasher
#10 Hex Nut
bb480i
Attaching The Wiring Hardware
BB480e
Installing The Front Cover
Installing The Switchable Battery Back Up Assembly IMI89–197
Installing The Battery Back Up Assembly – 13 
						

							4.0 Connecting The Battery Back-Up Assembly To The System
1. Connect the AC power and turn on the power supply switch in both DXPPlusmain and expansion cabinets.
CAUTION
Always connect the AC power, and turn on the power supplies before you connect the battery back-up
cables. Using a different connection sequence could cause equipment damage.
2. Connect a battery back-up cable between the charger cabinet and the power supplies in the DXPPlusmain
and expansion cabinets.
3. The battery back-up assembly includes a charger that maintains the batteries at full charge. Once you have
installed the cabinet assembly, connect its AC power cord tothe same AC outlet surge protector that
powers the DXPPlusmain common equipment cabinet.
Connecting The Battery Assembly To The System
PLUS004
Circuit Breaker
Power Line
Surge Protector
Dedicated
AC Outlet
IMI89–197 Installing The Switchable Battery Back Up Assembly
14 – Installing The Battery Back Up Assembly 
						

							5.0 Verifying The Battery Voltage
Every three months, use an accurate voltmeter to measure the no-load voltage of the battery back-up assembly.
The measured voltage range should be within 27–34.5 volts when the batteries are at full charge.
If the no-load voltage is lower than 27 volts, measure the charging voltage supplied by the common equipment
cabinet. The measured charging voltage must be 35 volts maximum.
If the charging voltage is low or if the voltage of freshly-charged batteries is no greater than 30 volts, contact your
technical service representative.
Green Status Lights
On = Batteries fully charges (>32 V)
On = AC power on
= +34.5 GND
= +34.5 GND
= -34.5 Volts
= -34.5 Volts
Fuse 5 AMP slow blow type
On = Batteries low (>27 V) On = Batteries under charged (>30 V){
{
PLUS002
Measured Voltage
(charger on and batteries fully charged)
Verifying The Battery Voltages
Installing The Switchable Battery Back Up Assembly IMI89–197
Installing The Battery Back Up Assembly – 15 
						

							6.0 Special Cautionary Battery Information
·Do not dispose of batteries in a fire as the cells may explode. Check with the local codes for possible disposal
instructions.
·Do not open or mutilate the batteries. Released electrolyte is corrosive and may cause damage to the eyes or
skin. It may be toxic if swallowed.
·Exercise care in handling batteries in order not to short the battery with conducting materials such as rings,
bracelets, and keys. The battery may over-heat and cause burns.
·Charge the batteries provided with or identified for use with the DXPPlusdigital communications system only
in accordance with the instructions and limitations specified in this publication.
·Observe proper polarity orientation when installing the batteries.
·Do not mix old and new batteries in the assembly.
·Do not mix batteries of different sizes or from different manufacturers in this product.
NOTICE
This symbol, when encountered on the equipment cabinet or on other
installed hardware, means: CAUTION—refer to the instruction manual.
Accredited by the Dutch Council
for Certification for certification
and registration activities.
Comdials Quality Management System Is
Certified To The ISO 9001 Standard.
Charlottesville, Virginia 22901-2829
R
World Wide Web:  http://www.comdial.com/
IMI89–197 Installing The Switchable Battery Back Up Assembly 
						

							Troubleshooting The DXPT1 Digital Carrier Transmission Option
On The DXP Plus Digital Communications System
What This Document Contains
1. Defining The T1 Terms   2
1.1 Introducing The DXPT1 6
1.2 Describing The Channel Service Unit (CSU) 6
1.3 Considering Pre-Installation Details 7
2. Troubleshooting The Physical Layer   8
2.1 Selecting Functions With DIP Switches SW1-1 Through SW1-8 8
2.2 Selecting Functions With DIP Switches SW2-1 Through SW2-8 8
2.3 Selecting Functions With DIP Switches LIU-1 Through LIU-4 9
2.4 Setting Up The DXOPT-SYN (Sync) Card 9
3. Troubleshooting The Protocol Layer  10
3.1 Defining The Signalling Bits For The E & M Protocol 10
3.2 Defining The Signalling Bits For The Direct Inward Dial (DID) Protocol   11
3.3 Defining The Signalling Bits For The Ground Start Protocol   11
3.4 Defining The Signalling Bits For The Loop Start Protocol 12
4. Using The Diagnostic Function 13
4.1 Understanding The Diagnostic Switches And Indicators 13
4.2 Requesting Cold Start Information 14
4.3 Requesting Information On Received Signal Strength   15
4.4 Requesting Information On Switch Settings 16
4.5 Requesting AB Signalling 17
4.6 Requesting Information On Trunk Assignments   18
4.7 Requesting Information About Channel State   19
4.8 Using The Hexadecimal Codes For Remote Diagnostics 20
5. Selecting The T1 PAD Settings 21
5.1 Setting T1 Transmit Level   21
5.2 Setting T1 Receive Level   21
6. Solving T1 Problems 21
A. APPENDIX A (Superframe and Extended Superframe Formats)  22
Referring To Other Documents
Installing The DXPT1 Digital Carrier Transmission Option, IMI89–193
Carrier-To-Customer Installation DS1 Metallic Interface, ANSI T1.403–1989
Private Branch Exchange (PBX) Switching Equipment for Voiceband Applications, 4.10 “Digital
Signaling and Supervision”, EIA/TIA–464A
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.IMI89–207.01
7/95 
						

							1 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.
IMI89–207 Troubleshooting The DXPT1 Installation
2 – Troubleshooting The DXPT1 Installation 
						

							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.
Troubleshooting The DXPT1 Installation IMI89–207
Throubleshooting The DXPT1 Installation – 3 
						

							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).
IMI89–207 Troubleshooting The DXPT1 Installation
4 – Troubleshooting The DXPT1 Installation 
						

							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.
Troubleshooting The DXPT1 Installation IMI89–207
Throubleshooting The DXPT1 Installation – 5