Black Box ME930C-RJ11 User manual

CUSTOMER
SUPPORT
INFORMATION
Order toll-free in the U.S. 24 hours, 7 A.M. Monday to midnight Friday: 877-877-BBOX
FREE technical support, 24 hours a day, 7 days a week: Call 724-746-5500 or fax [phone]
Mail order: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018
Web site: www.blackbox.com • E-mail: [email protected]
FEBRUARY 1999
ME930C-RJ11
Sync MP Line Driver Card
Power
TD
RD
Cntrl
In
Cntrl
Out
Test

1
FCC/IC STATEMENTS AND DECLARATION OF CONFORMITY
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.
DECLARATION OF CONFORMITY
This equipment complies with the Electromagnetic Compatibility (EMC) directive
and the Low Volatge Directive (LVD) of the Euopean Union.

2
SYNC MP LINE DRIVER CARD
DISCLAIMER
Under no condition shall the manufacturer be liable for any damages incurred by
the use of this product. These damages include, but are not limited to, the
following: lost profits, lost savings, and incidental or consequential damages arising
from the use of or inability to use this product.
TRADEMARKS
Any trademarks mentioned in this manual are acknowledged to be the property of the
trademark owners.

3
TABLE OF CONTENTS
Contents
Chapter Page
1. Specifications ............................................................................................. 4
2. Introduction ............................................................................................... 6
2.1 Features ............................................................................................... 6
2.2 Overview .............................................................................................. 6
3. Configuration ............................................................................................. 7
3.1 The Orientation and Default Settings of the DIP Switch ................. 8
3.2 Detailed Switch Settings ..................................................................... 9
3.3 Configuring the Rear Half-Card ...................................................... 10
4. Installation ................................................................................................ 13
4.1 The MicroRACK Chassis ................................................................... 13
4.2 The MicroRACK’s Power Supply ..................................................... 14
4.3 Installing the Sync MP Line Driver Card ......................................... 14
4.4 Connecting Cables to the Card ........................................................ 15
4.4.1 Making the RS-232 Connection ............................................. 15
4.4.2 Making the Twisted-Pair Connection .................................... 16
4.4.2.A Point-to-Point Twisted-Pair Connections ................. 16
4.4.2.B Multipoint Twisted-pair Connections ...................... 17
5. Operation ................................................................................................. 18
5.1 LED Status Monitors ......................................................................... 18
5.2 Power-Up ........................................................................................... 19
5.3 Test Modes ........................................................................................ 19
5.3.1 Local Analog Loopback .......................................................... 19
5.3.2 Remote Analog Loopback ...................................................... 20
6. Troubleshooting ...................................................................................... 21
6.1 Calling Black Box .............................................................................. 21
6.2 Shipping and Packaging ................................................................... 21
Appendix A: Cable Recommendations ......................................................... 22
Appendix B: Block Diagram .......................................................................... 23

4
SYNC MP LINE DRIVER CARD
1. Specifications
Compliance — FCC Part 15 Subpart J Class A, IC Class/classe A
Interfaces — Local: EIA/TIA RS-232C/ITU-T V.24, V.28;
Line: Proprietary balanced 4-wire (see Line Type below)
Protocol — Synchronous
Clock Source — Internal or external (from DTE), user-selectable; with
special cabling, can also use recovered receive clock
Data Rate — 19.2, 14.4, 9.6, 7.2, 4.8, 2.4, or 1.2 kbps (user-selectable)
Flow Control — RTS/CTS (hardware—RTS/CTS delay can be 0, 8, or
53 ms, user-selectable); can also pass through
X-ON/X-OFF (software)
Carrier Control — Constantly on or controlled by RTS (user-selectable)
Operation — Point-to-point or multipoint
Line Type — 4-wire unconditioned twisted pair, 19 to 26 AWG, with
20 pF/ft. (65.6 pF/m) or better capacitance
Optical Isolation — 150 Vrms minimum
User Controls — Front-panel test pushbutton;
8-position DIP switch for various options mounted on
front half-card;
(3) Jumpers for grounding options mounted on rear
half-card
Diagnostics — Simultaneous local and remote analog loopback,
controlled with front-panel pushbutton
Indicators — (10) Front-mounted LEDs:
(1) Power;
(1) Test;
(2) TD:
(1) for positive-state activity (green),
(1) for negative-state activity (red);

5
CHAPTER 1: Specifications
Indicators
(continued) — (10) Front-mounted LEDs (continued):
(2) RD:
(1) for positive-state activity (green),
(1) for negative-state activity (red);
(2) Cntrl In:
(1) for RTS from local device ON (green);
(1) for RTS from local device OFF (red);
(2) Cntrl Out:
(1) for carrier and Carrier Detect ON (green);
(1) for carrier and Carrier Detect OFF (red)
Connectors — (1) DB25 female for RS-232;
(1) Six-wire RJ-11 (RJ-12) for line;
(1) 50-pin card-edge on each half-card for mating
interconnection and chassis attachment
Surge Protection — Silicon Avalanche Diodes capable of dissipating
600 watts rms within 1 millisecond (initial reponse
time less than 1 picosecond)
Power — Input: 10-VAC from MicroRACK chassis (which has
a switchable 120-VAC or 240-VAC power supply);
Consumption: 700 mW typical
Temperature
Tolerance — 32 to 122˚F (0 to 50˚C)
Humidity
Tolerance — 0 to 95% noncondensing
Size — Not incl. protruding connectors, screws, and controls:
Front half-card:
3.1"H x 1"W x 4.8"D (7.8 x 2.5 x 12.2 cm);
Rear half-card:
3.3"H x 1"W x 2.6"D (8.4 x 2.5 x 6.7 cm);
Front and rear half-cards mated:
3.3"H x 1"W x 7.2"D (8.4 x 2.5 x 18.3 cm)
Weight — Net total, both half-cards: 4 oz. (114 g, 0.3 lb., 0.1 kg)

6
SYNC MP LINE DRIVER CARD
2. Introduction
2.1 Features
• Supports data rates from 1200 to 19,200 bps, user-selectable
• Optical isolation
• High-speed surge protection
• Supports distances up to 10 miles (16 km)
• Designed to be mounted in our MicroRACK system
• Full set of LED indicators
• Point-to-point or multipoint
• Loopback test modes
• Internal or external clocking
• Can perform hardware (RTS/CTS) flow control or pass through software
(X-ON/X-OFF) flow control
• Carrier can be constantly ON or controlled by RTS
2.2 Overview
The Sync MP Line Driver Card (our product code ME930C-RJ11) operates in full
duplex over four-wire cable (two unconditioned twisted pairs). The Card supports
data rates up to 19.2 Kbps and has a maximum range of 10 miles (at 1200 bps over
19-AWG wire). The Card also passes one control signal in each direction and
features both optical isolation and Silicon Avalanche Diode surge protection on
the data-line side. It can use its internal clock or the external clock from the
attached DTE.
The Sync MP Line Driver Card is designed to be mounted in our MicroRACK
system (product codes RM202 through RM216), a chassis that takes up 2U (3.5",
8.9 cm) of vertical space in a 19" rack. This chassis has a switchable 115/230-volt
power supply and hosts cards with a midplane architecture: One “function” half-
card slides into the front of the chassis and mates in the middle with a “connector”
half-card that slides into the rear of the chassis.
The Sync MP Line Driver Card has two built-in diagnostic tools: local and remote
loopback tests. Additionally, LEDs on the Card’s front panel allow you to visually
monitor communication.

7
CHAPTER 3: Configuration
3. Configuration
This chapter describes the location and orientation of the Sync MP Line Driver
Card’s configuration switch, provides detailed instructions for setting each switch
position, and describes jumper settings for the rear half-card.
As shown in Figure 3-1 below, the Card’s “function” front half has an eight-
position DIP switch labeled “SW1” that you can use to configure the Card for any
of a wide range of synchronous applications. This DIP switch is accessible when the
Card is slid out of the rack chassis. Once configured, the Card is designed to
operate transparently, without need for frequent reconfiguration: Just set it and
forget it!
Figure 3-1. The front half-card of the Sync MP Line Driver Card.
SW1
(position 1 on left)

8
SYNC MP LINE DRIVER CARD
3.1 The Orientation and Default Settings of the DIP Switch
The eight-position DIP switch on the Sync MP Line Driver Card allows you to
specify the Card’s data rate, clocking method, RTS/CTS delay, and carrier-control
method. Figure 3-2 below shows the orientation of the DIP switch with respect to
the “ON” and “OFF” settings of its switch positions. Table 3-1 below summarizes
the factory-default settings of these switch positions.
Figure 3-2. DIP switch SW1.
Table 3-1. SW1’s factory-default settings.
Position Function Factory-Default
Setting
1 Data Rate OFF
2 " OFF (9600 bps)
3"ON
4(Reserved for (N/A)
future use)
5 Transmit Clock ON (Internal)
6 RTS/CTS Delay ON (8 ms)
7 " OFF
8 Carrier Control OFF (Constant)
12345678
ON ON
OFF

9
CHAPTER 3: Configuration
3.2 Detailed Switch Settings
This section provides detailed information about the function of each DIP-switch
position and lists all of their possible settings. Use this section as a configuration
guide for applications where the Sync MP Line Driver Card’s default settings would
not provide correct results.
1. Data Rate (Positions 1 through 3)
Switch positions 1 through 3 are set in combination to allow the Card to be used at
data rates from 1200 bps up to 19,200 bps.
Pos. 1 Pos. 2 Pos. 3 Data Rate in bps
ON ON ON 1200
OFF ON ON 2400
ON OFF ON 4800
ON ON OFF 7200
OFF OFF ON 9600 (default)
OFF ON OFF 14,400
ON OFF OFF 19,200 settings are identical
OFF OFF OFF 19,200
2. Position 4 is reserved for future use. Do not change its setting.
3. Transmit Clock (Position 5)
Switch position 5 is used to specify the Card’s clocking method. The Card will
provide an internal clock on DB25 Pin 15 if position 5 is set to OFF (the default),
or receive an external clock from the attached DTE on DB25 Pin 24 if position 5
is set to ON.
Although the Card can’t be directly set to use recovered receive clock from the
remote Card, it always outputs that signal on DB25 Pin 17. So you can “trick” the
local Card into using receive clock by setting it for external clock (position 5 ON)
and attaching a special cable to its DB25 connector. This cable must not only pass
Pin 17 on the Card to Pin 17 on the DTE (which must be set for receive clock) but
must also loop Pin 17 on the Card back to Pin 24 (the external clock lead) on the
Card. If you want such a cable, please call Black Box for technical support.

10
SYNC MP LINE DRIVER CARD
4. RTS/CTS Delay (Positions 6 and 7)
Switch positions 6 and 7 are used together to specify RTS/CTS delay. After request
to send (RTS) is raised by the host terminal, the Card raises CTS after a slight delay
in order to give the remote terminal time to receive an incoming signal. Depend-
ing on the type of environment, select either no delay or an 8- or 53-ms delay.
Pos. 6 Pos. 7 Delay in milliseconds
ON ON Zero (no delay)
ON OFF Eight (default)
OFF OFF Fifty-three
5. Carrier Enable (Position 8)
Switch position 8 is used to specify how the carrier signal is raised. In most point-to-
point, full-duplex applications, the carrier signal can remain constantly “high,” so
you can leave this set to “constant carrier” (position 8 OFF, the default). But in
multipoint environments, although each slave can be left set to “constant carrier,”
you must set the host to “controlled by RTS” (position 8 ON).
3.3 Configuring the Rear Half-Card
The rear “connector” half-card of the Sync MP Line Driver Card has one RS-232
interface (a DB25 female connector) and one balanced 4-wire interface (a six-
wire
RJ-11, sometimes called RJ-12, female connector). Figure 3-3 below shows these
interfaces.
Figure 3-3. The Card’s RS-232 and 4-wire interfaces.

11
CHAPTER 3: Configuration
Prior to installation, you will need to examine this half-card and be sure its
jumpers are configured properly for your application. Figure 3-4 below shows
where the jumpers are. These jumpers determine various grounding characteristics
for the RS-232 and twisted-pair lines.
Figure 3-4. The jumper locations.
Figure 3-5 below shows how the jumpers can be placed: either connecting
pegs 1 and 2 or connecting pegs 2 and 3.
Figure 3-5. Possible jumper placements.
123 123
JB2
(peg 1 on left)
JB4
(peg 1 on left)
JB3
(peg 1 on left)

12
SYNC MP LINE DRIVER CARD
Table 3-2 below summarizes the factory-default settings of the jumpers. Following
this overview is a detailed description of each strap’s function.
Table 3-2. The factory-default settings of jumpers JB2, JB3, and JB4.
Jumper Function Factory-Default Setting
JB2 Line Shield and Jumper on positions 2 & 3
Frame Ground (grounds isolated)
JB3 DTE Shield (Pin 1) and Jumper on positions 2 & 3
Frame Ground (grounds isolated)
JB4 Frame Ground and Jumper on positions 2 & 3
Signal Ground (grounds isolated)
JB2: Line Shield and Frame Ground
This jumper affects the grounding on the 4-wire line interface. With pegs 1 and 2
connected, this jumper links RJ-11 Pins 1 and 6 to the Card’s frame ground. If
you’re using shielded twisted-pair cable, these pins can be used as connection
points for the twisted-pair cable’s shield (but the shield should be connected to
one of the two Cards only—never to both!). With pegs 2 and 3 connected (the
default setting), Pins 1 and 6 remain connected to each other, but are “lifted”
(isolated) from the Card’s frame ground.
Pegs 1 & 2 connected = Line shield tied to frame ground
Pegs 2 & 3 connected = Line shield isolated from frame ground (default)
JB3: DTE Shield (DB25 Pin 1) and Frame Ground
This jumper affects the grounding on the RS-232 interface to the DTE. With pegs 1
and 2 connected, this jumper links DB25 Pin 1 (the RS-232 “Shield” or “Protective
Ground” lead) to the Card’s frame ground. (If you are using shielded RS-232 cable
with the shield connected to Pin 1, it should be connected at one end of the cable
only—never at both ends!) With pegs 2 and 3 connected (the default setting), Pin 1
is “lifted” (isolated) from the Card’s frame ground.
Pegs 1 & 2 connected = DTE shield (DB25 Pin 1) tied to frame ground
Pegs 2 & 3 connected = DTE shield isolated from frame ground (default)
JB4: Signal Ground and Frame Ground
This jumper also affects the grounding on the RS-232 interface—signal ground in
this case. With pegs 1 and 2 connected, this jumper links DB25 Pin 7 (the RS-232
“Signal Ground” lead) to the Card’s frame ground. With pegs 2 and 3 connected
(the default setting), Pin 7 is “lifted” (isolated) from the Card’s frame ground.
Pegs 1 & 2 connected = Signal ground (DB25 Pin 7) tied to frame ground
Pegs 2 & 3 connected = Signal ground isolated from frame ground (default)

13
CHAPTER 4: Installation
4. Installation
This chapter describes the functions of the MicroRACK system, tells how to install
the front and rear half-cards of the Sync MP Line Driver Card in its chassis, and
provides diagrams for wiring the interface connections correctly.
4.1 The MicroRACK Chassis
The 16-Port MicroRACK chassis (our product code RM216), shown in Figure 4-1
below, has slots for sixteen short-range modem cards, as well as its own power
supply. Measuring only 3.5" (8.9 cm) high, the MicroRACK is designed to occupy
only 2U of vertical space in a 19" rack. Sturdy front handles allow the MicroRACK
to be extracted and transported conveniently.
If you short-range communication needs are more modest, we also offer 2-port
(RM202), 4-port (RM204), and 8-port (RM208) versions of the MicroRACK chassis.
Figure 4-1. The MicroRACK chassis.

14
SYNC MP LINE DRIVER CARD
4.2 The MicroRACK’s Power Supply
The power supply preinstalled in the MicroRACK uses the same mid-plane
architecture as the modem cards. The front half-card of the power supply slides in
from the front, and the rear half-card slides in from the rear. They plug into one
another in the middle of the rack. The front half-card is then secured with spring-
loaded thumbscrews and the rear half-card with conventional metal screws.
The power supply’s on/off switch is located on its front panel. When the power
supply is plugged in and switched on, a red LED on the supply’s front panel will
glow. Since the MicroRACK is a “hot-swappable” rack, it is not necessary for you
to install the Sync MP Line Driver Card (or any other compatible cards) before
switching on the power supply, and you can switch off the power supply at any
time without harming the installed cards.
If you should ever need to replace the power supply’s fuse or switch the
power supply from 115 to 230 VAC, please refer to the MicroRACK’s manual.
4.3 Installing the Sync MP Line Driver Card
As described earlier, the Sync MP Line Driver Card is made up of a front
“function” half-card and a rear “connector” half-card. The two half-cards meet
inside the rack chassis and plug into each other with mating 50-pin card-edge
connectors. Use the following steps as a guideline for installing each Sync MP Line
Driver Card in the MicroRACK chassis. (Note that the MicroRACK supports “hot-
swapping,” so you don’t have to turn it off before installing or removing cards.)
1. Slide the rear “connector” half-card into the back of the chassis along the
chassis’ metal rails.
2. Secure the rear half-card using the included metal screws.
3. Slide the “function” half-card into the front of the chassis. It should meet
the rear half-card when it’s almost all the way inside the chassis.
4. Push the front half-card gently into the card-edge receptacle of the rear
half-card. It should click into place.
5. Secure the front half-card using its spring-loaded thumbscrews.

15
CHAPTER 4: Installation
4.4 Connecting Cables to the Card
As mentioned earlier, the rear “connector” half-card of the Sync MP Line Driver
Card has one RS-232 port (a DB25 female connector) for local connections and
one 4-wire twisted-pair port (a six-wire RJ-11 female) for connections between line
drivers.
4.4.1 M AKING THE RS-232 C ONNECTION
NOTE
If you want the Card to use receive clock, the RS-232 cable must be
specially pinned; see Section 3.2.
The RS-232 port is pinned out as DCE (Data Communications Equipment)
according to the EIA/TIA RS-232C and ITU-T V.24 interface standards, as shown
in Figure 4-2 below. It can be connected to other RS-232 equipment in these ways:
• To DTEs (Data Terminal Equipment) with DB25 RS-232 connectors, such as
those on sync terminals or the second COM port on many PCs: Use straight-
through-pinned shielded cable such as our product code EDN25C.
• To DTEs with DB9 male RS-232 connectors, such as the first COM port on
many PCs: Use shielded AT modem cable such as our product code EVMBMC.
• To other DCEs with DB25 female connectors, such as modems or muxes:
Use shielded synchronous RS-232 tail-circuit cable such as our product code
EYN255C.
Figure 4-2. The Card’s RS-232 pinout.
(FG) FRAME GROUND
(TD) TRANSMIT DATA
(RD) RECEIVE DATA
(RTS) REQUEST TO SEND
(CTS) CLEAR TO SEND
(DSR) DATA SET READY
(SG) SIGNAL GROUND
(DCD) DATA CARRIER DETECT
FROM CARD
FROM CARD
TO CARD
TO CARD
TO CARD
FROM CARD
TO CARD
FROM CARD
FROM CARD
FROM CARD
TRANSMIT CLOCK
RECEIVE CLOCK
DATA TERM. READY (DTR)
EXTERNAL CLOCK
15
17
20
24
1
2
3
4
5
6
7
8
DIRECTION STANDARD RS-232C/V.24 “DCE” SETTING DIRECTION

16
SYNC MP LINE DRIVER CARD
4.4.2 M AKING THE
T WISTED -P AIR C ONNECTION
The Sync MP Line Driver Card operates full duplex over two twisted pairs. In all
applications, the twisted-pair wire must be 26 AWG or thicker, unconditioned, dry
metallic wire. (See Appendix A for a table of wire grades, distances, and data rates.)
CAUTION!
The Card can only communicate in a closed data circuit with another
Sync MP Line Driver Card. Trying to connect two of these Cards across
a dialup analog circuit, such as those used by telephones and standard
analog modems, will not work and might damage both the Cards and the
phone line.
4.4.2.A Point-to-Point Twisted Pair Connections
The 4-wire port is prewired for a standard telco wiring environment. Establishing a
4-wire twisted-pair circuit between two or more Sync MP Line Driver Cards requires
a shielded or unshielded crossover cable, as shown in Table 4-1 and Figure 4-3
below. (You
can build such cables from bulk CAT5 cable such as our product code
EVNSL70A.)
Note that (a) although positive and negative are shown here, the
Card is not actually sensitive to polarity; (b) you can connect the cable shield to
Pin 1 or 6 at one end (do not connect the shield at both ends!); and (c) the color
codes listed are standard for this type of wiring, but the colors of your wires might
be different.
Table 4-1. Pinouts for RJ-11 to RJ-11 Cabling
Local RJ-11 Remote RJ-11
Signal Wire Pin................Pin Wire Signal
Abbrev. Color No.................No. Color Abbrev.
GND Blue 1 6 White GND
RCV– Yellow 2....................4 Red XMT+
XMT+ Green 3....................5 Black RCV–
XMT– Red 4....................2 Yellow RCV–
RCV+ Black 5....................3 Green XMT+
GND White 6 1 Blue GND
Figure 4-3. The Card’s RJ-11 socket.
1 BLUE
2 YELLOW
3 GREEN
4 RED
5 BLACK
6 WHITE

17
CHAPTER 4: Installation
4.4.2.B Multipoint Twisted-Pair Connections
The Sync MP Line Driver Card supports multipoint applications using a star
topology. You just have to be sure that carrier control, determined by the setting
of position 8 of DIP switch SW1, is set correctly for each of your Cards (see
Section 3.2). Maximum distance between the units will vary based on the number
of drops, data rate, wire gauge, etc. Refer to Appendix A for general guidelines; for
help determining the distance you can run in your particular application, call
Black Box Technical Support.
Figure 4-4 below shows how to properly wire the Cards’ two-pair cabling for a
multipoint star topology. Note that no ground connection is needed.
Host First Slave Second Slave
XMT RCV RCV
XMT RCV RCV
RCV XMT XMT
RCV XMT XMT
Figure 4-4. Multipoint star wiring.

18
SYNC MP LINE DRIVER CARD
5. Operation
Once you have configured each Sync MP Line Driver Card and connected the
cables to them, you are ready to operate them. This chapter describes the Card’s
LED status monitors, the power-up procedure, and the use of the Card’s built-in
loopback test modes.
5.1 LED Status Monitors
The Sync MP Line Driver Card has ten front-panel status LEDs that indicate the
condition of the Card-toCard and Card-to-local-device links. Figure 5-1 below shows
the relative front-panel positions of the LEDs, and below that are descriptions of
each LED’s function.
Figure 5-1. The Card’s LEDs and controls.
• The green “PWR” LED glows when power is being applied to the Card
through its midplane chassis connection.
• The green “TD” and “RD” indicators blink to show positive-state data activity.
The red “TD” and “RD” indicators blink to show negative-state data activity.
Solid red indicates a connection in an idle state.
• The green “Cntrl In” and “Cntrl Out” indicators glow solid to show that the in-
band control signal is ON, while the red “Control In” and “Control Out”
indicators glow solid to show that the control signal is OFF. Here’s how this
works (assuming that both DTEs are set for hardware flow control):
If the local DTE needs the remote DTE to start sending data, it should raise
RTS (the signal that comes into the Card on DB25 Pin 4). This causes the local
Card to put its transmit leads in a low-impedance (positive/negative) state and
Power
TD
RD
Cntrl
In
Cntrl
Out
Test

19
CHAPTER 5: Operation
simultaneously light its green Cntrl In LED. The remote Card senses the low
impedance on the transmit lines, raises CD (the signal that goes out to the
remote DTE on the Card’s DB25 Pin 8), and lights its green Cntrl Out LED.
When the remote DTE senses that CD is ON, it will begin transmitting.
When the local DTE wants the remote DTE to stop sending data, it should
drop RTS. This causes the local Card to put its transmit leads in a high-
impedance (zero) state and simultaneously light its red Cntrl In LED. The
remote Card senses the high impedance on the transmit lines, drops CD to the
remote DTE, and lights its red Cntrl Out LED. When the remote DTE senses
that CD is OFF, it will interpret this as loss of carrier and cease transmitting
until CD comes back ON again.
• The green “TEST” LED will glow when the loopback test modes are activated.
5.2 Power-Up
There is no power switch on the Sync MP Line Driver Card: Power is automatically
applied to the Card when its card-edge connector makes contact with the
MicroRACK chassis’ midplane socket (as long as the chassis’ power supply is
turned on). Note once again that the Card is “hot-swappable”—it will not be
damaged by plugging it in or removing it while the MicroRACK is powered up.
When the local and remote Cards are both powered up and are passing data
normally, the LEDs should look like this:
• PWR = green
• TD & RD = flashing red and green
• Control In & Control Out = green
• TEST = off
5.3 Test Modes
The Sync MP Line Driver Card performs two diagnostic loops: local analog
loopback and remote analog loopback. These test modes are activated
simultaneously by pressing the “Test” button on the Card’s front panel so that it
latches in the “in” position. Contrast normal operation as shown in Figure 5-2 on
the next page with the loopback testing described below and shown in Figure 5-3
on the next page.