Black Box MicroNTU G.703 Series User manual

CUSTOMER
SUPPORT
INFORMATION
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Mail order: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018
Web site: www.blackbox.com • E-mail: [email protected]
JUNE 1999
MT245A
MT246A
MicroNTU G.703 Card (120 ohm)
MicroNTU G.703 Card (75 ohm)
Power
Loopback
Network
Master
Clock
Normal
MicroNTU
G.703

1
MICRONTU G.703 CARD (120 OR 75 OHM)
FEDERAL COMMUNICATIONS COMMISSION
AND
INDUSTRY CANADA
RADIO FREQUENCY INTERFERENCE STATEMENTS
This equipment generates, uses, and can radiate radio frequency energy and if not
installed and used properly, that is, in strict accordance with the manufacturer’s
instructions, may cause interference to radio communication. It has been tested
and found to comply with the limits for a Class A computing device in accordance
with the specifications in Subpart J of Part 15 of FCC rules, which are designed to
provide reasonable protection against such interference when the equipment is
operated in a commercial environment. Operation of this equipment in a
residential area is likely to cause interference, in which case the user at his own
expense will be required to take whatever measures may be necessary to correct
the interference.
Changes or modifications not expressly approved by the party responsible for
compliance could void the user’s authority to operate the equipment.
This digital apparatus does not exceed the Class A limits for radio noise emission from
digital apparatus set out in the Radio Interference Regulation of Industry Canada.
Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limites
applicables aux appareils numériques de la classe A prescrites dans le Règlement sur le
brouillage radioélectrique publié par Industrie Canada.

2
MICRONTU G.703 CARD (120 OR 75 OHM)
NORMAS OFICIALES MEXICANAS (NOM)
ELECTRICAL SAFETY STATEMENT
INSTRUCCIONES DE SEGURIDAD
1. Todas las instrucciones de seguridad y operación deberán ser leídas antes de
que el aparato eléctrico sea operado.
2. Las instrucciones de seguridad y operación deberán ser guardadas para
referencia futura.
3. Todas las advertencias en el aparato eléctrico y en sus instrucciones de
operación deben ser respetadas.
4. Todas las instrucciones de operación y uso deben ser seguidas.
5. El aparato eléctrico no deberá ser usado cerca del agua—por ejemplo, cerca
de la tina de baño, lavabo, sótano mojado o cerca de una alberca, etc..
6. El aparato eléctrico debe ser usado únicamente con carritos o pedestales que
sean recomendados por el fabricante.
7. El aparato eléctrico debe ser montado a la pared o al techo sólo como sea
recomendado por el fabricante.
8. Servicio—El usuario no debe intentar dar servicio al equipo eléctrico más allá
a lo descrito en las instrucciones de operación. Todo otro servicio deberá ser
referido a personal de servicio calificado.
9. El aparato eléctrico debe ser situado de tal manera que su posición no
interfiera su uso. La colocación del aparato eléctrico sobre una cama, sofá,
alfombra o superficie similar puede bloquea la ventilación, no se debe colocar
en libreros o gabinetes que impidan el flujo de aire por los orificios de
ventilación.

3
MICRONTU G.703 CARD (120 OR 75 OHM)
10. El equipo eléctrico deber ser situado fuera del alcance de fuentes de calor
como radiadores, registros de calor, estufas u otros aparatos (incluyendo
amplificadores) que producen calor.
11. El aparato eléctrico deberá ser connectado a una fuente de poder sólo del
tipo descrito en el instructivo de operación, o como se indique en el aparato.
12. Precaución debe ser tomada de tal manera que la tierra fisica y la polarización
del equipo no sea eliminada.
13. Los cables de la fuente de poder deben ser guiados de tal manera que no
sean pisados ni pellizcados por objetos colocados sobre o contra ellos,
poniendo particular atención a los contactos y receptáculos donde salen del
aparato.
14. El equipo eléctrico debe ser limpiado únicamente de acuerdo a las
recomendaciones del fabricante.
15. En caso de existir, una antena externa deberá ser localizada lejos de las lineas
de energia.
16. El cable de corriente deberá ser desconectado del cuando el equipo no sea
usado por un largo periodo de tiempo.
17. Cuidado debe ser tomado de tal manera que objectos liquidos no sean
derramados sobre la cubierta u orificios de ventilación.
18. Servicio por personal calificado deberá ser provisto cuando:
A: El cable de poder o el contacto ha sido dañado; u
B: Objectos han caído o líquido ha sido derramado dentro del aparato; o
C: El aparato ha sido expuesto a la lluvia; o
D: El aparato parece no operar normalmente o muestra un cambio en su
desempeño; o
E: El aparato ha sido tirado o su cubierta ha sido dañada.

4
MICRONTU G.703 CARD (120 OR 75 OHM)
Contents
1. Specifications.....................................................................................................5
2. Introduction ......................................................................................................6
3. Configuration....................................................................................................7
3.1 Front-Card Configuration..........................................................................7
3.2 Rear-Card Configuration ...........................................................................9
3.2.1 Configuring the 120-Ohm Rear Card .............................................9
3.2.2 Configuring the 75-Ohm Rear Card .............................................12
4. Installation.......................................................................................................14
4.1 The MicroRack and Power Supplies .......................................................14
4.2 Installing the MicroNTU G.703 Card in the MicroRack Chassis ..........16
4.3 Connection to the G.703 Network ..........................................................17
4.3.1 Twisted-Pair (120-Ohm) Connection (MT245A).........................18
4.3.2 Dual Coax BNC (75-Ohm) Connection (MT246A).....................18
4.4 Connection to the Terminal Device .......................................................18
4.4.1 EIA-530 (RS-422) Terminal Connection (MT245A)....................18
4.4.2 X.21 Terminal Connection (MT246A).........................................19
5. Operation ........................................................................................................20
5.1 Power-Up ..................................................................................................20
5.2 LED Status Monitors ................................................................................20
5.3 Loopback Test (LAL) ..............................................................................22
Appendix. Interface Standards ..........................................................................23

5
CHAPTER 1: Specifications
Network Interface G.703
Network Rate 2.048 Mbps
Network Connectors MT245A: One modular RJ-45 connector
(120-ohm); MT246A: Two BNC (75-ohm)
Terminal Interface MT245A: EIA-530 (RS-422) on DB25 female;
MT246A: CCITT X.21 on DB15 female
Internal Interface Connection to MicroRack 2, 4, 8, or 16
(RM202, RM204, RM208, or RM216) midplane
architecture chassis via (2) 50-pin male card
edge connectors
Terminal Rate 2.048 Mbps
Diagnostics Loopback Test
Indicators LEDs for power, network, master clock, and
loopback test
Clocking Internal, external (network receive loop)
Fuse 400 mA for 120V applications; 200 mA for 240V
applications
Receiver Sensitivity -10 dB (0 dB = 2.4V)
Operating Temperature 32° to 140°F (0° to 60°C)
Humidity 0 to 95%, noncondensing
Altitude Up to 15,000 feet (4570 m)
Power Supply Rackmount power supply is switchable between
120 and 240 VAC; chassis supplies 10 VAC to
the MT245A/MT246A, typical consumption is
1 watt
Size 3.1"H x 0.95"W x 5.4"D (7.9 x 2.4 x 13.7 cm)
1. Specifications

6
MICRONTU G.703 CARD (120 OR 75 OHM)
The MicroNTU G.703 Card receives unstructured, synchronous 2.048-Mbps
data from a G.703 network and sends it to a router, bridge, multiplexor, or
other device. The Card is available in two interface options: 120-ohm twisted
pair to the network and EIA-530 (RS-422) to the terminal (part number
MT245A), or 75-ohm dual coax to the network and X.21 to the terminal
(MT246A). The EIA-530 terminal interface can also be adapted to X.21
using an EIA RS-530 to CCITT X.21 adapter cable (call Black Box).
The MicroNTU G.703 Card is designed to mount in the MicroRack 2, 4, 8,
or 16 (RM202, RM204, RM208, RM216). These operate with a switchable
120/240-VAC power supply or optional 48-VDC power supply. (The power
supply is included with the MicroRack 16. MicroRacks 2, 4, and 8 do not
include the power supply. You must purchase PS460A, the 120/240-VAC unit,
or PS461A, the 48-VDC unit, separately.) The Cards are mounted in a mid-
plane architecture: Front “function” cards and rear “interface” cards can be
hot-swapped independently, providing great flexibility.
The MicroNTU G.703 Card supports internal or external network (receive
loop) clocking. Loopback test is Local Analog Loop (LAL) via front-panel
mounted switch, and front-panel LEDs monitor power, network, master clock,
and test loop.
2. Introduction

7
CHAPTER 3: Configuration
The MicroNTU G.703 Card (MT245A) uses seven jumpers (or four for
MT246A), which allow the unit to be configured for a wide range of
applications. Designed around a mid-plane architecture, the MicroNTU
G.703 Card incorporates both front and rear cards. Configuration of both
may be necessary. The jumpers are accessible when the cards are slid out of
the rack chassis. Once configured, the MicroNTU G.703 Card is designed to
operate transparently, without need for frequent re-configuration: Just set it
and forget it.
3.1 Front-Card Configuration
The MicroNTU G.703 Card front card has two jumpers (LK6 and LK7), which
are mounted on the PC board (see Figure 3-1). These jumpers set clocking
and data inversion.
Figure 3-1. Jumper locations.
3. Configuration
LK7
LK6

8
MICRONTU G.703 CARD (120 OR 75 OHM)
LK6: Tx Clock Source
Jumper LK6 is a three-post jumper. Figure 3-2 shows the three possible
orientations of this jumper.
Figure 3-2. Possible strap positions for jumper LK6.
The setting for jumper LK6 determines whether the MicroNTU G.703 Card
will provide an internal clock, or will be receiving a clock from an external
device.
LK6 Setting
Position 1 and 2 Internal/Master Clock (Default) [Master]
Position 2 and 3 Network Clock - Slave - Network
NC Not a valid setting
3 2 1
Front of Card
3 2 1 3 2 1

9
CHAPTER 3: Configuration
LK7: Data Inversion
The setting for jumper LK7 determines whether data will be inverted or not
inverted.
LK7 Setting
Strap Installed Data Inverted
Strap Omitted Data Not Inverted (Default)
3.2 Rear-Card Configuration
The MicroNTU G.703 Card has two rear interface card options: for the
MT245A, 120-ohm (modular) network and EIA-530 (DB25) terminal, or,
for the MT246A, 75-ohm (dual BNC) network and X.21 (DB15) terminal.
Each is configured differently.
3.2.1 C ONFIGURING THE 120-O HM R EAR C ARD
The 120-ohm rear card has five configuration jumpers (LK1 through LK5).
Figure 3-3 shows the locations of the jumpers on the 120-ohm rear card.
Figure 3-3. 120-ohm rear card jumper locations.
LK5
LK4
LK1
LK2
LK3

10
MICRONTU G.703 CARD (120 OR 75 OHM)
Table 3-1 shows the factory-default jumper settings for the 120-ohm rear card.
Following Table 3-1 is a description of each jumper’s function and possible
settings. When configuring the jumpers, take care not to lose the individual
straps.
Table 3-1. Summary of default jumper settings
for 120-ohm rear card
120-Ohm Rear Card Jumpers
Jumper Function Factory Default
LK1 TX Pin 4 to GND Strap Off*
LK2 RX Shield (Pin 3) to GND Strap Off
LK3 RX Pin 2 to GND Strap Off*
LK4 Clock Synchronization Strap Off
LK5 (DTE) SGND to FGND Strap On
*Mandatory setting. All others are up to user’s discretion.
LK1: (Transmit Pair) Pin 4-to-Ground Connection
This setting determines whether or not pin 4 of the transmit pair is sent to
earth ground. This connection should not be made in most cases.
LK1 Setting
Strap On Pin 4-to-GND Connection Made
Strap Off Pin 4-to-GND Connection Broken
LK2: (Receive Shield) Pin 3-to-Ground Connection
This setting determines whether or not the RX shield (pin 3) is connected to
earth ground. This connection may help EMC performance in some cases.
LK2 Setting
Strap On Pin 3-to-GND Connection Made
Strap Off Pin 3-to-GND Connection Broken

11
CHAPTER 3: Configuration
LK3: (Receive Pair) Pin 2-to-Ground Connection
This setting determines whether or not pin 2 of the receive pair is sent to
earth ground. This connection should not be made in most cases.
LK3 Setting
Strap On Pin 2-to-GND Connection Made
Strap Off Pin 2-to-GND Connection Broken
LK4: Clock Synchronization (EIA-530 versus X.21)
This setting determines whether clocks are common or separate. Separate
(non-synchronized) clocks are used for the EIA-530 terminal interface.
Common (synchronized) clocks are used for the X.21 terminal interface. If
clocks are synchronized, a DB25-to-DB15 adapter cable should be used
between the MicroNTU G.703 Card and the X.21 terminal device (see the
Appendix for pinning).
LK4 Setting
Strap On Clocks Synchronized (X.21)
Strap Off Clocks Not Synchronized (EIA-530)
LK5: DTE Signal Ground-to-Frame Ground (with Resistor)
This setting determines whether or not the DTE signal ground (DB25 pin 7)
is connected to frame ground (pin 1) by way of a 100-ohm resistor. This
connection is recommended in the EIA-530 specification as a current limiter
for ground-fault events.
LK5 Setting
Strap On SGND-to-FGND Connection Made
(via 100-ohm resistor)
Strap Off SGND-to-FGND Connection Broken

12
MICRONTU G.703 CARD (120 OR 75 OHM)
3.2.2 C ONFIGURING THE 75-O HM R EAR C ARD
The 75-ohm rear card has two configuration jumpers (LK1 and LK2).
Figure 3-4 shows the locations of the jumpers on the 75-ohm rear card.
Figure 3-4. 75-ohm rear card jumper locations.
LK2
LK1

13
CHAPTER 3: Configuration
Table 3-2 shows the factory-default jumper settings for the 75-ohm rear card.
Following the table is a description of each jumper’s function and possible
settings. When configuring the jumpers, take care not to lose the individual
straps.
Table 3-2. Summary of default jumper settings
for 75-ohm rear card
75-Ohm Rear Card Jumpers
Jumper Function Factory Default
LK1 RX Shield to GND Strap Off
LK2 (DTE) SGND to FGND Strap On
LKI: Receive Shield-to-Ground Connection
This setting determines whether or not the RX shield is connected to earth
ground. This connection may help EMC performance in some cases.
LK1 Setting
Strap On RX Shield-to-GND Connection Made
Strap Off RX Shield-to-GND Connection Broken
NOTE
TX shield is always tied directly to GND (no resistor).
LK2: DTE Signal Ground-to-Frame Ground (with Resistor)
This setting determines whether or not the DTE signal ground (DB15 pin 8)
is connected to frame ground (pin 1) by way of a 100-ohm resistor. This
connection is recommended as a current limiter for ground-fault events.
LK2 Setting
Strap On SGND-to-FGND Connection Made
Strap Off SGND-to-FGND Connection Broken

14
MICRONTU G.703 CARD (120 OR 75 OHM)
This chapter describes the functions of the MicroRack 2, 4, 8, and 16 chassis,
tells how to install front and rear MicroNTU G.703 Cards in the chassis, and
provides diagrams for wiring the interface connections correctly.
4.1 The MicroRack and Power Supplies
The MicroRack comes with two, four, eight, or sixteen card slots. The
MicroRack 16 includes its own power supply. If you will be using the
MicroRack 2, 4, or 8, you must order a power supply (see the next page for
more information on PS460A and PS461A). Measuring only 3.5 inches high,
the MicroRack is designed to occupy only 2U in a 19-inch rack. Sturdy front
handles allow the MicroRack 16 to be extracted and transported conveniently.
Figure 4-1. The MicroRack 16.
ON
OFF
Power
MicroRack System
AC Power Supply
4. Installation

15
CHAPTER 4: Installation
The power supply (PS460A or PS461A) used in the MicroRack uses the same
mid-plane architecture as the modem cards. The front card of the power
supply slides in from the front, and the rear card slides in from the rear.
They plug into one another in the middle of the rack. The front card is then
secured by thumbscrews and the rear card by conventional metal screws.
Switching the Power Supply On and Off
The power supply on/off switch is located on the front panel. When plugged
in and switched on, a red front-panel LED will glow.
Since the MicroRack is a “hot-swappable” rack, it is not necessary for any cards
to be installed before switching on the power supply. The power supply may
be switched off at any time without harming the installed cards.
Replacing the Power-Supply Fuse
The rack-chassis power supply uses a 400-mA fuse for 120-VAC circuits, and a
200-mA fuse for 240-VAC circuits. The fuse compartment is located just below
the AC socket on the rear card. To replace the fuse, follow these steps:
1) Turn the power switch off and remove the power cord.
2) Using a small screwdriver, pop the compartment open (it will slide open
like a drawer). Depending upon the exact part used, the drawer may slide
completely out of the fuse holder or it may stop partway out.
3) Note that there are two fuses in the drawer. The front fuse is the spare,
and the rear fuse is the “active” fuse.
4) If the active fuse appears to be blown, remove it from the clips and
replace it with the spare from the front compartment. Note the size and
rating of the blown fuse before discarding it.
5) Buy a replacement fuse at an electronics store. (Note: For continued
protection against the risk of fire, replace only with the same type and
rating of fuse.)

16
MICRONTU G.703 CARD (120 OR 75 OHM)
Switching the Power Supply Between 120 and 240 Volts
Although the MicroRack is shipped from the factory with a customer-specified
power-supply configuration, you may change the configuration yourself. Here
are the steps to switch the configuration of the power supply between 120 and
240 VAC:
1) Remove the front power-supply card and locate the two-position switch
near the back of the card. Slide the switch to the desired voltage. (Note:
The actual values on the switch may be “110/220” or “115/230.”)
2) Verify that the existing fuse is the correct value (400 mA for the 120-volt,
200 mA for the 240-volt).
3) Connect the power-supply cord.
4.2 Installing the MicroNTU G.703 Card in the MicroRack Chassis
The MicroNTU G.703 Card is made up of a front card and a rear card. The
two cards meet inside the MicroRack chassis and plug into each other by way
of mating 50-pin card edge connectors. Use the following steps as a guideline
for installing each MicroNTU G.703 Card in the chassis.
1) Slide the rear card into the back of the chassis along the metal rails
provided.
2) Secure the rear card using the metal screws provided.
3) Slide the card into the front of the chassis. It should meet the rear card
when it’s almost all the way into the chassis.
4) Push the front card gently into the card-edge receptacle of the rear card.
It should click into place.
5) Secure the front card using the thumbscrews.
NOTE
Since the MicroRack chassis allows hot-swapping of cards, it is not
necessary to power down the rack when you install or remove a
MicroNTU G.703 Card.

17
CHAPTER 4: Installation
4.3 Connection to the G.703 Network
The MicroNTU G.703 Card supports 2.048-Mbps communication over an
unstructured G.703 network. Both 120- and 75-ohm interface cards are
available (see Figure 4-2).
Figure 4-2. Rear interface card options.
MT245A MT246A
Dual BNC (75-Ohm)
RJ-45 (120-Ohm)
DB15FDB25F

18
MICRONTU G.703 CARD (120 OR 75 OHM)
4.3.1 T WISTED -P AIR (120-O HM ) C ONNECTION (MT245A)
The 120-ohm version of the MicroNTU G.703 Card is equipped with a single
RJ-45 jack for connection to a 120-ohm twisted-pair G.703 network interface.
The pinout of this jack is as follows:
RJ-45 Pins Signal
1 and 2 Receive pair (from network)
3 Shield reference point
4 and 5 Transmit pair (to network)
6 Shield reference point
7 Not used
8 Not used
4.3.2 D UAL C OAX BNC (75-O HM ) C ONNECTION (MT246A)
The 75-ohm version of the MicroNTU G.703 Card is equipped with dual
female BNCs (TX and RX) for connection to a 75-ohm dual coax G.703
network interface. The outer conductor of the coax cables is isolated from
system earth ground.
4.4 Connection to the Terminal Device
The MicroNTU G.703 Card is wired as a DCE, and—when configured
properly—supports communication with a variety of terminal (DTE) devices.
4.4.1 EIA-530 (RS-422) T ERMINAL C ONNECTION (MT245A)
The 120-ohm rear card for the MicroNTU G.703 Card is equipped with a
female DB25 connector. This connector is wired according to the EIA-530
standard (see the wiring diagram in the Appendix). To connect to an RS-530
terminal (DTE), use a standard DB25 cable.
NOTE
The 120-ohm rear card must be set for non-synchronized clocking (see
Section 3.2.1) in order to support the EIA-530 interface.

19
CHAPTER 4: Installation
4.4.2 X.21 T ERMINAL C ONNECTION (MT246A)
The 75-ohm rear card for the MicroNTU G.703 Card is equipped with a
female DB15 connector, wired according to the CCITT X.21 standard (see
the Appendix). To connect to an X.21 terminal (DTE), use a standard DB15
cable.
NOTE
The 120-ohm rear card can also be used with X.21 terminal devices. To
do this, the Card must be set for synchronized clocking (see Section
3.2.1), and a DB25-to-DB15 adapter cable must be used. See the
Appendix if you are going to construct your own cable.