RSD-20
High Speed Digital Sharing Device
Installation and Operation Manual
Notice
This manual contains information that is proprietary to RAD Data Communications. No part of this
publication may be reproduced in any form whatsoever without prior written approval by RAD
Data Communications.
No representation or warranties for fitness for any purpose other than what is specifically
mentioned in this manual is made either by RAD Data Communications or its agents.
For further information contact RAD Data Communications at the address below or contact your
local distributor.
RAD data communications RAD data communications RAD data communications
Headquarters
US East
US West
12 Hanechoshet Street
Tel Aviv 69710 Israel
Tel: 972-3-6458181
Fax: 972-3-6498250
900 Corporate Drive
Mahwah, NJ 07430 USA
Tel: (201) 529-1100
Fax: (201) 529-5777
3631 South Harbor
Boulevard
Suite 250
Santa Ana, CA 92704
Fax: (714) 850-1555
© 1999 RAD Data Communications
Publication No. 544-200-11/99
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Manufacturer’s Name:
RAD Data Communications Ltd.
Manufacturer’s Address:
12 Hanechoshet St.
Tel Aviv 69710
Israel
declares that the product:
Product Name:
RSD-10
Conforms to the following standard(s) or other normative document(s):
EMC:
EN 55022 (1994)
Limits and methods of measurement of radio disturbance
characteristics of information technology equipment.
EN 50082-1 (1992) Electromagnetic compatibility - Generic immunity
standards for residential, commercial and light industry.
Safety:
EN 60950 (1992/93) Safety of information technology equipment, including
electrical business equipment.
Supplementary Information:
The product herewith complies with the requirements of the EMC Directive 89/336/EEC and the
Low Voltage Directive 73/23/EEC. The product was tested in a typical configuration.
Tel Aviv, October 7th, 1996
Haim Karshen
VP Quality
European Contact: RAD Data Communications GmbH, Lyoner Strasse 14, 60528 Frankfurt am Main, Germany
TABLE OF CONTENTS
1
INTRODUCTION
1.1
1.2
1.3
1.4
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2
Ordering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3
2
INSTALLATION
2.1
2.2
2.3
2.4
2.5
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1
Site Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1
Physical Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1
Electrical Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1
System Synchronization and Clock Distribution . . . . . . . . . . . . . . . . . . . 2.5
3
OPERATION
3.1
3.2
3.3
3.4
3.5
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1
Controls and Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1
Operating Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2
Operational Field Strapping Changes . . . . . . . . . . . . . . . . . . . . . . . . 3.3
Fault Isolation Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3
4
THEORY OF OPERATION AND APPLICATIONS
4.1
4.2
4.3
4.4
4.5
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1
Contention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1
Sub-channel Disable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1
Control Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6
APPENDIX A X.21 INTERFACE SIGNAL DESCRIPTION
APPENDIX B X.35 INTERFACE SIGNAL DESCRITPION
FIGURES
Figure 2.1
Figure 2.2
Figure 2.3
Figure 2.4
Figure 2.5
Figure 2.6
Figure 3.1
Figure 4.1
Figure 4.2
Figure 4.3
Figure 4.4
Figure 4.5
Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2
SD-20/V.35 PC Board Layout . . . . . . . . . . . . . . . . . . . . . . . . 2.4
RSD-20/X.21 PC Board Layout . . . . . . . . . . . . . . . . . . . . . . . 2.4
Synchronization on Main Channel Modem’s Clock . . . . . . . . . . . . . 2.5
Synchronization on Internal Clock . . . . . . . . . . . . . . . . . . . . . . 2.6
Synchronization on Sub-channel 1 . . . . . . . . . . . . . . . . . . . . . 2.7
Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1
Main Channel DTE with Sub-channel DCE . . . . . . . . . . . . . . . . . 4.4
Main Channel DCE with Sub-channel DTE . . . . . . . . . . . . . . . . . 4.4
Main Channel DTE with Sub-channel DTE . . . . . . . . . . . . . . . . . 4.5
Main Channel DCE with Sub-channel DCE . . . . . . . . . . . . . . . . . 4.5
RSD-20 Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6
TABLES
Table 2.1
Table 3.1
Table 3.2
Table A.1
Table B.1
PC Board Switch and Strap Selection . . . . . . . . . . . . . . . . . . . . 2.3
Control Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2
Indicator Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2
X21 Interface Signal Description . . . . . . . . . . . . . . . . . . . . . . . A.1
V.35 Interface Signal Description . . . . . . . . . . . . . . . . . . . . . . B.1
1
INTRODUCTION
1.1 GENERAL
The RSD-20, High Speed Digital Sharing Device, enables up to four high speed modems,
terminals or controllers to share a master modem, a multiplexer or a computer port in a
multipoint environment. The RSD-20 is compatible with synchronous equipment at data rates of
48, 56, or 64 kbps, with V.35 or X.21 interface.
1.2 FUNCTIONAL DESCRIPTION
The main channel transmits information to all sub-channels in parallel. Sub-channels contend to
transmit to the main channel by activating RTS/DCD (V.35), CONT/IND (X.21), or by data
transition (strap-selectable). If the control signal or sub-channel data is active, the transmit data
and control signals of the sub-channels are connected to the main channel. When the control
signal drops or data transmission stops, the control circuitry is switched to monitor other
sub-channels. A sub-channel is disconnected immediately after it drops the control signal or
transmits 16 idle bits.
A sub-channel can be automatically disabled if it stays active for longer than a preset time,
blocking all other sub-channels (streaming). The automatic disable resets itself as soon as the
sub-channel control signal drops, or transmits 16 idle bits. An indicator on the front panel will
light for each sub-channel which is disabled by automatic circuitry. Manual disabling of a
sub-channel is also possible via a front panel push button.
Three clock modes are supported:
1) Internal
2) External from the main channel
3) External from sub-channel 1
A built-in buffer overcomes phase differences between the clocks of modems connected to the
sub-channels and the RSD main channel transmit clock.
An additional buffer option is available for V.35 interface only. This buffer is required when the
equipment connected to more than one sub-channel must provide a clock and is unable to
accept an external clock. Examples are D.D.S. in the U.S., any digital service in other countries,
or modems that cannot be set to an external clock. This buffer compensates for phase
differences between the clocks of the modems connected to the sub-channel and the clock of
the RSD-20.
Installation and configuration of the RSD-20 is simple. Minimal strapping adjustments allow for
easy installation and operation. A DCE/DTE switch for the main channel and each sub-channel
eliminates the need for crossover cables. Only straight-through cables are used to connect the
modems or terminals to the RSD-20.
The RSD-20 is a desk-top unit, with special hardware available for mounting it onto a 19" rack.
1.1
RSD-20 OPERATOR'S MANUAL
INTRODUCTION
1.3 SPECIFICATIONS
Number of Sub-channels
Four
Channel Configuration
Lowest priority: Sub-channel 1
Highest priority: Sub-channel 4
Sub-channel Selection
Strap-selectable to:
Control signal RTS/DCD (V.35) or CONT/IND (X.21) ON
Data transitions
Sub-channel Deselection
RTS/DCD (V.35) or CONT/IND (X.21) OFF (in control contention)
16 bits of idle data (in data contention)
Sub-channel Disabling
Manual:
Via front panel switches
Automatic: If sub-channel stays connected for more than a pre-set time period
(32.4, 4, 0.5 sec for 64 or 48 kbps; 36.8, 4.7 or 0.6 for 56 kbps)
Transmit Clock Source
– Internal
– External derived from main channel
– External derived from sub-channel 1
Data Rates
Synchronous:
Internal Clock:
– Selectable 48, 64 kbps for 64 kbps option
– 56 kbps
External Clock:
– Derived from main channel (modem in internal mode)
– Derived from sub-channel 1 (up to 128 kbps)
Input and Output Interface
V.35 or X.21
Connectors
– Five 34-pin V.35, female,
– Five DB-15 X.21, female
Controls
Four manual sub-channel DISABLE switches, one per sub-channel;
Push-button switches
1.2
INTRODUCTION
RSD-20 OPERATOR'S MANUAL
Indicators
DATA:
Display data broadcast from main channel to sub-channels
ACTIVITY: 4 LEDs indicate which sub-channel has gained access to main channel
DISABLE: 4 LEDs indicate if sub-channel has been disabled automatically
ON:
RSD power is on
Power
115/230 VAC switchable;
10%; 47-63 Hz; 10 W
Physical
Height: 44 mm / 1.7 in (1U)
Width: 431 mm / 17.0 in
Depth: 208 mm / 8.2 in
Weight: 2 kg / 4.4 lb
Environment
o
o
Temperature:
Humidity:
0-50 C/32-122 F
Up to 90%, non-condensing
1.4 ORDERING
RSD-20/+/*/#
Digital Sharing Device
+ Specify:
64 for 64/48 kbps (selectable)
56 for 56 kbps
* Specify interface:
V.35 for V.35 interface
X.21 for X.21 interface
1.3
2
INSTALLATION
Access inside the equipment is only permitted to authorized service personnel.
2.1 GENERAL
This chapter provides information on performing the mechanical and electrical installation of the
RSD-20. After installation has been completed, refer to Chapter 3 for operating information and
system checkout to assure normal operation.
2.2 SITE PREPARATION
The RSD-20 must be installed within 1.5 m (5 feet) of a grounded AC outlet, and within 15 m
(50 feet) of the associated data terminals or modems.
Allow at least 90 cm (36 in) of frontal clearance for operating and maintenance accessibility.
Ensure that there is a minimum of 10 cm (4 in) clearance at the end of the unit for power and
interface cables.
2.3 PHYSICAL INSTALLATION
The RSD-20 is designed for placement on a table-top, or for mounting onto a 19" rack. It is
equipped with special brackets already assembled for mounting. These brackets can be easily
removed as follows:
1. Disconnect the power cord.
2. Unfasten the rear panel screw and slide back the top cover.
3. Unfasten the two screws from the bracket and remove the single bolt.
2.4 ELECTRICAL INSTALLATION
2.4.1 AC Power
AC power is supplied to the RSD-20 through a 1.5 m (5 ft) cord terminated by a grounded
3-prong plug. The AC cord is fused at the rear panel of the unit. A 0.4A slow-blow fuse is
required.
2.1
INSTALLATION
RSD-20 OPERATOR'S MANUAL
2.4.2 Rear Panel
Six connectors are located on the rear panel of the RSD-20, consisting of five channel
connectors (four for the sub-channels and one for the main channel) and one 3-pin power
connector, which also includes the fuse holder. The five channel connectors are 34-pin
connectors for the V.35 interface or 15-pin, D-type for the X.21 interface. The ON/OFF power
switch and the 110/220 VAC selection switch are located also on the rear panel (see Figure 2.1).
2.4.3 Internal Switches and Strap Selection
The internal switches and straps on the RSD-20 should be configured to meet system
requirements. In order to change the settings, the following steps should be followed:
a) Disconnect the AC power cable.
b) Remove the RSD-20 top cover, loosen the two screws on the rear panel and slide back the top
cover.
c) Identify the straps according to Table 2.1 and Figures 2.3 and 2.4.
POWER
MAIN CHANNEL
SUB CHAN.
4
SUB CHAN.
3
SUB CHAN.
2
SUB CHAN.
1
~230V
~115V
F-0.400A S.B.
Figure 2.1
Rear Panel
d) Install the straps/switches in the required position.
e) Reinstall the top cover.
CAUTION Disconnect the instrument from the input line power before removing
covers.
2.2
RSD-20 OPERATOR'S MANUAL
INSTALLATION
2.3
INSTALLATION
RSD-20 OPERATOR'S MANUAL
2.4
RSD-20 OPERATOR'S MANUAL
INSTALLATION
2.5 SYSTEM SYNCHRONIZATION AND CLOCK DISTRIBUTION
2.5.1 RSD-20/V.35
Four alternatives are available for synchronization of the system:
a)Main channel modem timing signals.
b) RSD-20 internal clock.
c) Sub-channel 1 modem timing signals.
d) Any sub-channel modem timing signals. For this the optional buffer is required.
2.5.1.1 Synchronization on Main Channel Modem Clock
a) Main channel modem – strapped to internal clock.
b) DCEs attached to sub-channels are strapped to external clock.
c) RSD-20 bit rate setting is ignored (bit rate is determined by main channel modem clock).
RSD-20
EXT. CLK
DCE
SUB DTE
EXT. CK
TX. CLK
DCE
INT. CK
MAIN
DTE
TX. CLK
SUB DCE
DTE
Figure 2.4
Synchronization on Main Channel Modem’s Clock
2.5
INSTALLATION
RSD-20 OPERATOR'S MANUAL
2.5.1.2 Synchronization on RSD-20 Internal Clock
a) RSD-20 baud rate should be strapped to the required speed.
b) DCEs attached to sub-channels should be strapped to external clock.
c) DCE attached to main channel should be strapped to external clock.
EXT. CLK
RSD-20
EXT. CLK
DCE
DCE
EXT. CK
SUB DTE
EXT. CK
TX. CLK
MAIN
DTE
TX. CLK
SUB DCE
DTE
TX. CLK
DTE
EXT. CK
MAIN
DTE
Figure 2.5
Synchronization on Internal Clock
2.6
RSD-20 OPERATOR'S MANUAL
INSTALLATION
2.5.1.3 Synchronization on Sub-channel 1
a) RSD-20 baud rate should be strapped to CLK-1.
b) DCE attached to main channel should be strapped to external clock.
c) DCEs attached to sub-channel 1 should be strapped to internal clock.
NOTE
Synchronization on sub-channel 1 is not recommended when the modem
connected to sub-channel 1 operates in switched carrier mode, as it
causes fluctuations in clock frequency and phase.
EXT. CLK
RSD-20
RCV. CLK
DCE
EXT. CK
DCE
RCV. CK
DCE
INT. CK
MAIN
DTE
SUB-1 DTE
SUB DCE
SUB DTE
TX. CLK
TX. CLK
DTE
TX. CLK
MAIN
DTE
DTE
EXT. CLK
DCE
EXT. CK
Figure 2.6
Synchronization on Sub-channel 1
2.7
INSTALLATION
RSD-20 OPERATOR'S MANUAL
2.5.1.4 External Clock for more than one Sub-channel
This option enables connection of more than one sub-channel to the line from the P.T.T. service.
Generally, the P.T.T. modems supply clock to every line – i.e. the P.T.T. has to provide the
clock. Since the modems are all from the same service, the clocks are synchronized. The
external buffer will compensate for phase differences between the clocks received from the
sub-channels. However, the external buffer option will not compensate for the clock differences,
if different clock sources are used.
2.5.2 RSD-20/X.21
The X.21 standard states that DCEs and DTEs will only have one clock signal (signal timing).
The direction of this clock is always from the DCE to DTE. This signal timing is used for the
transmit clock and receive clock.
According to this standard, four alternatives are available for the synchronization of the system
when working with the RSD-20/X.21:
a) Main channel is DTE (attached to a modem).
b)Main and all sub-channels are DCE (attached to DTEs).
c) Main channel is DCE (attached to a DTE and all sub-channels are DTE (attached to modems).
d) Main channel is DCE and sub-channels are mixed (DTEs and DCEs).
2.5.2.1 Main channel is DTE
(attached to a modem)
In this mode the RSD operates according to the signal timing of clock of the main channel
modem. DTEs attached to the RSD-20 sub-channels are synchronized to the mains clock.
DCEs attached to sub-channels are synchronized on their own signal timing. A special buffer,
integrated in the RSD-20/X.21, compensates for the phase difference between the modems of
the sub-channels and the main channel modem.
2.5.2.2 Main and all sub-channels are DCE
(attached to DTEs)
In this mode the RSD provides the clock to all ports attached to the main and sub-channels. The
RSD’s baud rate should be strapped to the appropriate system baud rate.
2.5.2.3 Main channel is DCE (attached to a DTE) and all sub-channels are DTE
(attached to modems)
In this mode the RSD’s baud rate is strapped to CLK-1. The DTE attached to the main channel
is synchronized to the RSD’s clock, the modems attached to sub-channels 2, 3, 4 should be
strapped to external clock, except for the modem attached to sub-channel 1 which should be
strapped to internal clock.
NOTE
It is also possible to work with the RSD’s internal clock in this mode, but
CLK-1 is preferred.
2.8
RSD-20 OPERATOR'S MANUAL
INSTALLATION
2.5.2.4 Main channel is DCE and sub-channels are mixed
(DTE and DCE)
In this mode one of the modems attached to the sub-channels (configured as DTE) should be
attached to sub-channel 1, and the RSD baud rate should be strapped to CLK-1.
The DTEs attached to the main and sub-channels are synchronized to the RSD’s clock; the
modems attached to the sub-channels are synchronized to their own clock; and the internal
buffer compensates for the phase difference between the signal timing of the modem attached to
sub-channel 1 to the rest of the modems.
NOTE
1.
2.
Working with RSD’s internal clock is also possible but CLK-1 is
preferred.
On DTE (sub-channels 1 to 4 and Main channel), the RSD-20 supplies
clock on pins 7 and 14 for DCE external clock (The DCE must support
external clock as in the ASM-20/8-X.21).
WARNING Before plugging in this unit, the protective ground (earth) terminals must
be connected to the protective conductor of the (mains) power cord. The
mains plug should only be inserted in a socket outlet provided with a
protective ground (earth) contact. The protective action must not be
negated by use of an extension cord (power cable) without a protective
conductor (grounding).
Ensure that only fuses with the required rated current, and specified type
(slow blow, 0.4A) are used for replacement. The use of repaired fuses,
and the short-circuiting of fuse holders is strictly forbidden.
Whenever it is likely that the protection offered by fuses has been
impaired, the instrument must be made inoperative and secured against
unintended operation.
With the unit power turned on, operating personnel are not exposed to
voltages in excess of 30 volts on any I/O pin, provided that the equipment
to which the RSD-20 is connected is safe.
2.9
3
OPERATION
3.1 GENERAL
This chapter details the RSD-20 controls and indicators, their functions, and operating
procedures.
The installation procedures given in Chapter 2 must be completed and checked before operation
of the RSD-20 is attempted.
NOTE
For an explanation of all the possible system installations of the RSD-20,
refer to Chapter 4.
3.2 CONTROLS AND INDICATORS
SUB-CHANNEL DISABLE
RSD-20
RAD
AUTOMATIC
ACTIVITY
1
2
3
4
POWER DATA
1
2
3
4
1
2
3
4
Figure 3.1
Front Panel
Four controls and ten indicators are located on the RSD-20 front panel; two controls are located
on the rear panel. Their functions are described in Tables 3.1 and 3.2.
3.1
RSD-20 OPERATOR'S MANUAL
OPERATION
Table 3.1
Control Functions
Control
Location
Function
Turns AC power ON or OFF
Power switch (with lamp) ON/OFF
110/220 VAC Selector
Rear Panel
Rear Panel
Selects main power source: 115 or 230 VAC
Four manual DISABLE push-button switches Front Panel
Manually deactivates sub-channels
connected to defective terminals or modems.
A depressed push button disables the
sub-channel
Table 3.2
Indicator Functions
Indicator
Functions
Power
Green LED is ON when power is present and the DC power
supply is O.K.
Main
Yellow LED flickers according to main channel XMT data
Four yellow LEDs flicker according to sub-channels XMT data
Sub-channels Activity 1-4
Automatic Disable 1-4
Four red LEDs light when the corresponding sub-channel has
been automatically disabled (due to time-out)
3.3 OPERATING PROCEDURE
3.3.1 Power Turn On
1) Make sure the power switch is turned to OFF.Set the 110/220 selector located on the rear
panel to the main voltage used in your country. The white arrow should point to the correct
main voltage.
2) Apply AC power by connecting the AC cord to the AC connector on the rear panel of the
RSD-20 and then plug it into the AC source.
3) Turn the power switch located on the rear panel to ON. The power switch should light up,
indicating that the main power is fed to the RSD-20 while the power LED (on the front panel)
should light indicating that the internal power supply is O.K.
3.3.2 Operation
The RSD-20 operates unattended, unless it is required to manually disable one or more
sub-channels.
3.3.3 Power Turn Off
To turn off the AC power to the RSD-20, simply switch off the power switch.
3.2
OPERATION
RSD-20 OPERATOR'S MANUAL
3.4 OPERATIONAL FIELD STRAPPING CHANGES
Access inside the equipment is only permitted to authorized service personnel.
If it becomes necessary to reconfigure the RSD-20 for a different type of operation, the internal
straps must be changed to correspond to the new operating mode. For guidance in repositioning
the straps, refer to the information given in Chapter 2 of this manual. It is recommended that the
straps be changed by an experienced technician.
CAUTION Do not open the top cover for strap changes before removing the AC
power from the unit.
3.5 FAULT ISOLATION PROCEDURE
WARNING These service instructions should be used by qualified personnel only.
Access inside the equipment is only permitted to authorized service personnel.
3.5.1 Power Supply
If AC power has been applied to the RSD-20 but the green power LED does not light up, check
installation according to the following procedure:
a) Verify that the 110/220 selector is set correctly.
b) Verify that the power switch light is on.
c) Unplug the AC cord and then pull out the fuse (located above 3-pin power connector). Check
the fuse and replace if necessary (0.4A S.B.).
d) Remove the top cover of the unit and check that the 5-pin power connector (connecting the
secondary wires of the transformer to the main card) is connected properly.
3.5.2 RSD Malfunction
If the Power LED is ON but the RSD-20 is not functioning in the system, proceed as follows:
a) Unplug the AC cord and remove the top cover.
b) Verify that all the DCE/DTE switches are set according to the data system requirements.*
c) Verify that the strap settings are correct.
d) Check the three large LSI chips (RJ-006) and if necessary reposition in the socket.
* In the V.35 option, check that main and sub-channel’s three switches are set to the same
position.
3.3
RSD-20 OPERATOR'S MANUAL
THEORY OF OPERATION AND APPLICATIONS
4
THEORY OF OPERATION AND APPLICATIONS
4.1 INTRODUCTION
This chapter contains a simplified functional description of the RSD-20, and covers the flow of
data, controls and clocks in all RSD-20 operating modes.
4.2 CONTENTION
RTS/DCD contention in V.35 interface is interchangeable with CONTROL/INDICATION
contention for X.21 interface. Sub-channel access to the main channel for data transmission is
controlled by RTS/DCD (Request to Send/Data Carrier Detect) or (CONTROL/INDICATION in
X.21 version) or data contention. When selected, the data and timing signals of the active
sub-channels pass through the contention circuit and the SELECT/DESELECT circuit of the
sub-channels to the elastic buffer, where data is clocked in and out of the main channel.
When a continuous mark is detected, and if strapped to data contention, the
SELECT/DESELECT circuit breaks the data path of the active sub-channel. It then selects
another sub-channel and resets the buffer. Otherwise the sub-channel will remain connected
until RTS/DCD or (CONTROL/INDICATION) go down.
4.3 SUB-CHANNEL DISABLE
Manual or automatic disable of streaming sub-channels is possible. If the sub-channel is DTE
(connected to a modem) the RSD-20 drops RTS, and if the sub-channel is DCE (connected to
port) the RSD-20 drops DCD and CTS and X.21 drops CONT. In addition, the RSD-20 will stop
transmitting data to the sub-channel, and will ignore any data received from it.
4.3.1 Manual Disable
Manual disable is activated by four push-button switches, one for each sub-channel, which are
located on the front panel. Disabling the sub-channel is achieved by depressing the appropriate
switch. The sub-channel will remain inactive until the switch is released by depressing it again.
4.3.2 Automatic Disable
A streaming sub-channel is disabled automatically if it has stayed active for longer than a preset
period of time, thereby blocking all other sub-channels. Automatic disabling of a sub-channel
resets itself each time RTS/DCD or data (in data contention mode) drops. Selection of one of
three different time delays or non-active mode as indicated on the PCB.
4.4
4.4 CONTROL SIGNALS
Sub-channel control signals are combined to provide a composite signal to the main channel.
Control signals from the main channel are passed to all sub-channels in parallel.
The following are details of control signals:
4.4.1 Main Channel Control Signals
4.4.1.1 RSD-20/V.35
RTS (DCD)
In RTS/DCD (CONTROL/INDICATION) contention mode – Follows RTS (DCD) of the selected
sub-channel.
In Data Contention mode – “ON” if RTS (DCD) of one of the sub-channels is “ON”.
CTS
“ON” only when the CTS signals of all active sub-channels are “ON”. A sub-channel is active if it
is connected to a modem and the DSR signal is “ON” (Enables connection of dial-up modems to
the RSD-10).
DSR (DTR)
“ON” if DTR (DSR) of one of the sub-channels is “ON”.
4.4.1.2 RSD-20/X.21
CONTROL/INDICATION
Is dependent upon contention mode and “C/I to MAIN” jumper
If the “C/I to MAIN” jumper is selected for the “sub-channel” state, and the contention mode is
data, then the C/I to MAIN is “ON” if the C/I of one of the sub-channels is “ON”.
If “C/I to MAIN” jumper is in the “ON” state, then the C/I to MAIN is always “ON”, regardless of
the contention mode.
4.4.2 Sub-channel Control Signals
4.4.2.1 RSD-20/V.35
RTS (DCD)
Follows the main channel RTS (DCD) (Unless the sub-channel is disabled).
CTS
In RTS contention mode – Selected channel follows CTS signal of main channel.
In Data Contention mode – sub-channel receives CTS from main channel immediately after it
raises RTS. (Unless the sub-channel is disabled).
DSR (DTR)
Follows the main channel DSR (DTR)
4.1
RSD-20 OPERATOR'S MANUAL
4.4.2.2 RSD-20/X.21
CONTROL/INDICATION
THEORY OF OPERATION AND APPLICATIONS
If the “C/I to Sub-channel” jumper is in the “MAIN CHANNEL” state, the C/I to sub-channel
follows the main C/I (unless the sub-channel is disabled, then the C/I is OFF). If the “C/I to
sub-channel is in the ”ON" state, all of the sub-channels’ C/O are “ON” irrespective of the main
channel C/I.
4.2
THEORY OF OPERATION AND APPLICATIONS
RSD-20 OPERATOR'S MANUAL
4.3
RSD-20 OPERATOR'S MANUAL
THEORY OF OPERATION AND APPLICATIONS
Figure 4.1
Main Channel DTE with Sub-channel DCE
Figure 4.2
Main Channel DCE with Sub-channel DTE
4.4
THEORY OF OPERATION AND APPLICATIONS
RSD-20 OPERATOR'S MANUAL
Figure 4.3
Main channel DTE with Sub-channel DTE
Figure 4.4
Main channel DCE with Sub-channel DCE
4.5
RSD-20 OPERATOR'S MANUAL
THEORY OF OPERATION AND APPLICATIONS
4.5 APPLICATIONS
The RSD-20 operates in one of six modes: modem sharing, port sharing, remote port sharing,
local port sharing, mix modem sharing and mix port sharing. System configurations incorporating
the RSD-20 in each operating mode are described in Figure 4.1.
The following should be taken into consideration when configuring an RSD-20 system:
The rate of the sub-channel and main channel modems and/or ports must be equal to the data
rate strapped within the RSD-20.
Figure 4.5
RSD-20 Operating Modes
4.6
APPENDIX A
Table A.1
X21 Interface Signal Description
X.21
SIGNAL NAME
SHIELD
PIN
1
G
T
GROUND
8
TRANSMIT
2
9
R
C
I
RECEIVE
4
11
CONTROL
3
10
INDICATION
SIGNAL TIMING
EXTERNAL CLOCK
5
12
S
-
6
13
7
14
APPENDIX B
Table B.1
V.35 Interface Signal Description
V.35
Signal Function
34-pin Stand-Alone
Pin
Circuit
Protective Ground
Signal Ground
A
Frame
101
B
Signal GND 102
Transmitted Data
S
P
TD(B)
TD(A)
103
103
Received Data
R
T
RD(A)
RD(B)
104
104
Request to Send
Clear to Send
C
D
E
H
F
RTS
CTS
DSR
DTR
DCD
105
106
107
108
109
Data Set Ready
Data Terminal Ready
Carrier Detect
External Transmit Clock
U
W
SCTE(A)
SCTE(B)
113
113
Transmit Clock
Receive Clock
Y
a
SCT(A)
SCT(B)
114
114
X
V
SCR(B)
SCR(A)
115
115
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