Metrodata DC3 00 Series Manuale utente
DC3X00
www.metrodata.co.uk
Metrodata DC3X00 User Manual
Metrodata Ltd
Laxton House
Crabtree Office Village
Eversley Way
Egham
Surrey TW20 8RY
United Kingdom
tel: +44 (0) 1784 744700
fax:+44 (0) 1784 744701
website: www.metrodata.co.uk
1 INTRODUCTION 1
1. 1 About the DC3X00 1
1. 2 Safety 2
1. 3 Electromagnetic Compatibility 2
1. 4 EN50022 Declaration 2
1. 5 FCC Declaration 2
1. 6 Power supply 2
1. 7 FCC Declaration 2
1. 8 Technical Overview 3
1 . 8. 1 G.703 Signal Transmission 3
1 . 8. 2 G.704 Framing 3
1 . 8. 3 E1 Path Overhead 4
1. 9 DTE Nx64K Payload 4
2 DESCRIPTION OF PARTS 5
2. 1 Rear panel 5
2. 2 Status display - rear panel 5
2. 3 Power supply 6
2. 4 Unbalanced E1 Line port (BNC) 7
2. 5 Balanced RJ45 E1 Line (Network) Port 8
2 . 5. 1 Connecting to a terminal device 8
2 . 5. 2 Connecting to a network device 9
2 . 5. 3 RJ45 Connector layout 9
2 . 5. 4 Cable lengths and types 10
2. 6 Alarm Extension (RJ45) 10
2. 7 X.21 DTE Port 11
2. 8 V.35 DTE Port 12
3 INSTALLATION & SET-UP 13
3. 1 Setting-up the Bit-switches 13
3 . 1. 1 Select RJ45/BNC 14
3 . 1. 2 CRC4 and T/S 16 bypass 14
3 . 1. 3 Framing 14
3 . 1. 4 Timeslot 16 by-pass & bandwidth 14
3 . 1. 5 Setting Up Start T/S and Bandwidth 15
3 . 1. 6 Timing 15
3 . 1. 7 Line coding 16
3 . 1. 8 Test Loop 16
3. 2 Connecting up 17
4 ALARMS, TROUBLESHOOTING & TESTING 18
4. 1 Alarms 18
4. 2 Troubleshooting 19
4. 3 Test Loop 20
5 DC3X00 SPECIFICATIONS 21
5. 1 DC3X00 Product Specification 21
5. 2 DC3X00 Clocking Diagram 22
5. 3 Glossary 23
INTRODUCTION
1
1 INTRODUCTION
1. 1 About the DC3X00
The DC3X00 is used to interface between a fractional E1 (2.048Mbit/s) Nx64K service and
an X.21 or V.35 port which connects to a bridge or router. The model DC3000 has an X.21
interface, and the model DC3200 has a V.35 interface. Both models are described in this
manual. There is a choice of either BNC or RJ45 connectors for the E1 service on the rear
panel of the unit. DC3X00’s are used in pairs, one on either side of a WAN (Wide Area
Network) link.
LAN
LAN
Figure 1.1 DC3X00 installation
INTRODUCTION
2
1. 2 Safety
The DC3X00 should not be connected to cabling which would be required by BS6701 to be
equipped with over-voltage protection. The following ports are designated SELV (Safety
Extra Low Voltage) within the scope of EN41003:
X.21 port
V.35 port
Fractional E1 Line port (BNC or RJ45)
Alarm extension RJ45 port
These ports should only be connected to SELV ports on other equipment in accordance with
EN60950 clause 2.3.
1. 3 Electromagnetic Compatibility
In order to ensure EMC compliance all signal and data cables and connectors must use a
screened connector shell with a screened cable. The cable screen must be terminated to the
screened connector shell and not connected to any pins of the connector. Failure to use the
correct connector may compromise EMC compliance.
1. 4 EN50022 Declaration
The DC3X00 is a Class A product. In a domestic environment it may cause radio interference
in which case the user may be required to take adequate measures.
1. 5 FCC Declaration
This equipment has been tested and found to comply with the limits for 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 radiocommunications. 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 its own expense.
1. 6 Power supply
The DC3X00 is powered by a mains power supply with an input voltage range 100-250 VAC/
50-60 Hz.
An alternative -48V DC power supply unit is available.
Further details are given in Section3.
Safety notes:
Excessive voltages are present inside the unit. There are no user serviceable parts inside
the unit, and the cover should not be removed by unqualified personnel. The unit must not
be exposed to damp or condensing conditions. The DC3X00 must be connected to safety
earth for correct operation.
1. 7 FCC Declaration
This equipment has been tested and found to comply with the limits for a Class A digital
device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide
INTRODUCTION
3
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 radiocommunications. 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 its own expense.
1. 8 Technical Overview
The DC3X00 is used on unframed E1/G.703, framed E1/G.704 (CRC4) or
E1/G.704 (no CRC4)digital services. Technical overviews of G.703 and G.704 are provided.
1 . 8. 1 G.703 Signal Transmission
The signal is transmitted on 75 ohm unbalanced coax or 120 ohm balanced twisted pair. The
signal has alternate mark inversion (AMI) characteristics in accordance with G.703. A mark
is transmitted as a 0.5 unit interval (UI) wide pulse of amplitude 2.37V on 75 ohm coax, or
3.0V on 120 ohm twisted pair. Alternate marks have opposing polarity so that '111' is
transmitted as a positive pulse, a negative one and then another positive one. The pulses
have a duration of 50% so that strings of '1s' can be identified as a series of pulses. This is
because clocking information is derived from the transmitted signal. In addition, strings of
zeros are replaced with high-density binary 3 (HDB3) code words to ensure pulse density
(and therefore clocking information) and an average DC potential of 0V.
The transmission rate is 2.048 Mbps. The worst case delay through the DC3X00 is 2
milliseconds, and the worst case round trip delay is 8 milliseconds.
1 . 8. 2 G.704 Framing
Groups of 248 bits are grouped into frames together with an 8-bit overhead at the start of the
frame called TIME SLOT 0 (TS0). The frame length is therefore 256 bits, and the frame
repetition rate is 8KHz. The 248 bits of payload are divided into 31 timeslots of 8 bits each
(TS1 - TS31). With the data in each timeslot regarded as an individual channel, 31 channels
may be multiplexed together into one E1 trunk. As well as dividing the trunk between payload
and overhead, groups of frames are associated into multi-frames. A synchronisation pattern
is spread across the multiframe. Frames are alternately FAS (Frame Alignment Signal) and
NFAS (Non Frame Alignment Signal) frames.
INTRODUCTION
4
1 . 8. 3 E1 Path Overhead
8 bits are used for path overhead and provide framing, alarm information, error detection and
management. The bits of TS0 are used alternatively by the FAS and NFAS frames as
follows:
Figure 1.2 E1 Path overhead
1. 9 DTE Nx64K Payload
The DC3X00 permits the 2.048Mbits/s E1 LINE port to operate with multiple channels of
Nx64Kbit/s where N may vary between 1 and 31. There are restrictions placed upon the
utilisation of bandwidth:
Timeslots used must form a contiguous block
The total number of timeslots allocated must be less than or equal to 31 (or 30 if Timeslot 16
is by-passed).
If Timeslot 16 by-pass is ENABLED by setting the bit-switch labelled BYP16 to ON,
Timeslot 16 is by-passed in allocating channels sequentially to timeslots; i.e. you could then
select Timeslots ….14,15,17,18…….
Bit No Function
FAS Frame
1CRC bit
2 to 8 Frame alignment signal (FAS) 0011011
NFAS Frame
1International bit : contains CRC multi-
frame alignment signal and remote block
error (REBE) information
2NFAS bit
3Remote alarm indication (RAI)
4 to 8 National bits
DESCRIPTION OF PARTS
5
2 DESCRIPTION OF PARTS
2. 1 Rear panel
All connections into and out of the DC3X00 are made through the rear panel. The rear panels
are shown in schematic form below.
ALARM
EXT
ALARM
EXT
Pin1
-48V
Pin3
0V
L
_
_
Figure 2.1 DC3000 rear panel (100-250 VAC supply)
Figure 2.2 DC3200 rear panel (-48VDC supply)
2. 2 Status display - rear panel
There is a status LED on the right hand side of the rear panel which indicates the status of
the unit as shown in the figure below.
Figure 2.3 Rear panel status LED
Status LED Meaning
Off No mains power present
Red steady LOS
Red/Off flashing LOS and DTE Alarm
Red/Green flashing LOF or AIS Alarm
Red/Green/Off flashing AIS and DTE Alarm
Green/Red/Off flashing LOF and DTE Alarm
Green/Off flashing DTE Alarm
Green steady DC3X00 is operating normally
DESCRIPTION OF PARTS
6
Notes:
If the LED flashes red/green, disconnect the DTE (X.21 or V.35) signal to the DC3X00 in
order to distinguish between LOF and AIS alarms. The loss of the DTE signal will then cause
either the red/green/off or the green/red/off sequence to occur, depending upon the
condition which has occurred.
2. 3 Power supply
The DSU is powered by a mains supply with an input voltage of 100-250VAC, 50-60Hz,
35-15 mA. The input power consumption is approximately 3.5 watts. The DC3X00 is
provided ex-factory with a 250mA internal fuse. Mains power is connected via the IEC inlet
on the rear of the unit.
An alternative -48VDC powered unit is available. The input voltage and current ranges are
minus 36 to minus 72 volts DC, 100-50mA. A Buccaneer type socket is fitted to the rear
panel, and a plug is provided with the unit for the customer’s own wiring. The connections
are labelled on the rear panel of the DC3X00.
On some units, an additional Ground stud may be located on the rear panel to permit a
separate Ground connection to be made.
Figure 2.4 -48VDC connections
Note: The DSU must be connected to mains safety earth for correct operation.
Pin no Connection
1-48VDC
2 Ground
30VDC
DESCRIPTION OF PARTS
7
2. 4 Unbalanced E1 Line port (BNC)
The network is connected to the BNC connectors at the rear of the unit as shown below :
Figure 2.5 BNC connection
Cable lengths should be restricted to those defined below:
Figure 2.6 Cable lengths
Note: The total maximum attenuation of each of the cables attached to the network port must
not exceed 6dB when measured at 1024 MHz. The frequency/attenuation characteristic of
the cables attached to the network port shall follow a root frequency law.
Pin Function
Tip Signal
Ring Shield
Cable Max Length (metres)
UR202 720
RG59U 600
BT2002 650
BT2003 680
DESCRIPTION OF PARTS
8
2. 5 Balanced RJ45 E1 Line (Network) Port
The layout of the female RJ45 network port mounted on the rear panel is shown below:
Figure 2.7 RJ45 network port layout
2 . 5. 1 Connecting to a terminal device
A connecting cable from the network port to a terminal port such as a router or a PABX is
straight through. Connections are defined in the table below.
Figure 2.8 Connection from DSU to terminal device
Pin Function
1Tx tip
2Tx ring
3Tx shield
4Rx tip
5Rx ring
6Rx shield
7Not connected
8 Not connected
DSU
port pin
DSU port
function
Terminal port
pin
Terminal port
function
1Tx tip 1Rx tip
2Tx ring 2Rx ring
3Tx shield 3Rx shield
4Rx tip 4Tx tip
5Rx ring 5Tx ring
6Rx shield 6Tx shield
7Not connected Not connected Not connected
8 Not connected Not connected Not connected
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