East Coast Datacom DMM-4DC User manual

TABLE OF CONTENTS
Page 124.5 TECHNICAL SPECIFICATIONS ............................... Page114.4 USER NOTES ............................................... .Page 104.3 CLOCKING / APPLICATION DIAGRAM ........................ Page 94.2 FACTORY DEFAULT CHART ................................. .Page 84.1 EIA INTERFACE CHART ..................................... .Page 84.0 - APPENDIX ...................................................... .Page 73.5 MODEM (DCE) AND TERMINAL (DTE) CONNECTION .......... .Page 73.4 DEFAULT CONFIGURATION SWITCH SETTINGS ............... .Page 63.3 POWER / GROUND CONNECTION ............................ .Page 63.2 VOLTAGE FUSES ........................................... .Page 63.1 INPUT VOLTAGE ........................................... .Page 6CHAPTER 3 - INSTALLATION ......................................... .Page 52.13 DCE / DTE SWITCHES ...................................... .Page 52.12 NORMAL OR FORCED CLEAR TO SEND (CTS) (PORTS 1-4) .... .Page 52.11 ENABLE CONTROL (PORTS 1 - 4) ............................ .Page 42.10 CASCADING OR CONCATENATION ......................... .Page 42.9 UNEXPLAINED STREAMING TERMINALS ..................... .Page 42.8 MANUAL DTE/DCE REMOVAL ............................... .Page 32.7 SYNC AND ASYNC SELECTION .............................. .Page 32.6 ANTI-STREAMING .......................................... .Page 32.5 SUBCHANNEL SERVICE MODES ............................. .Page 32.4 RS-232 ELECTRICAL INTERFACE ............................. .Page 22.3 CLOCKING, INTERNAL AND EXTERNAL ...................... .Page 22.2 REAR PANEL CONNECTORS ................................. .Page 22.1 FRONT PANEL INDICATORS AND SWITCHES ................. .Page 2CHAPTER 2 - BASIC OPERATION ..................................... .Page 21.2 THEORY OF OPERATION .................................... .Page 11.1 FUNCTIONAL DESCRIPTION ................................. .Page 1CHAPTER 1 - INTRODUCTION ........................................ .

OPERATIONS MANUAL
PART NUMBER: 162000
MODEL: DMM-4DC
DESCRIPTION: DIGITAL MIXING MODULE
-48VDC POWER SUPPLY
January 22, 2002
Manufactured By:
East Coast Datacom, Inc.
FOR TECHNICAL SUPPORT CALL:
East Coast Datacom, Inc.
245 Gus Hipp Blvd., STE 3
Rockledge, FL 32955
TEL: [phone] or [phone]
FAX: [phone]
Web Site: http://www.ecdata.com
PT # 162012-A

SAFETY WARNING
Always observe standard safety precautions during installation, operation and maintenance of
this product. To avoid the possibility of electrical shock, be sure to disconnect the DC power
source from the DMM-4DC unit before you remove the cover or perform any repairs.
PROPRIETARY NOTICE
The information contained herein is proprietary to East Coast Datacom, Inc. Any reproduction or
redistribution of this publication, in whole or in part, is expressly prohibited unless written
authorization is provided by East Coast Datacom, Inc.
WARRANTY NOTICE
WARRANTIES: East Coast Datacom, Inc. (hereafter referred to as E.C.D.) warrants that its
equipment is free from any defects in materials and workmanship. The warranty period shall be
three (3) years from the date of shipment. E.C.D.'s sole obligation under its warranty is limited
to the repair or replacement of defective equipment, provided it is returned to E.C.D.,
transportation prepaid, within a reasonable period. This warranty will not extend to equipment
subjected to accident, misuse, alterations or repair not made by E.C.D. or authorized by E.C.D. in
writing.
PUBLICATION NOTICE
This manual has been compiled and checked for accuracy. The information in this manual does
not constitute a warranty of performance. E.C.D. reserves the right to revise this publication and
make changes from time to time in the content thereof. E.C.D. assumes no liability for losses
incurred as a result of out-of-date or incorrect information contained in this manual.

CHAPTER 1 - INTRODUCTION
1.1 FUNCTIONAL DESCRIPTION
The RS-232 Digital Mixing Module (DMM-4DC) is a network expansion device for modem sharing or
port sharing applications in polled or contention environments. The DMM-4DC allows up to four
devices to share a modem / DSU or computer port. Any combination of terminals and modems may be
used in a network environment. Each port of the DMM-4DC may be selected as a DCE or DTE interface.
Once installed, system and network efficiency are increased through higher host processor utilization
coupled with the significant decrease in idle time between host / terminal traffic sessions.
Ideal for either synchronous or asynchronous network environments, the DMM-4DC is protocol
transparent at data rates up to 128Kbps. The DMM-4DC may be configured to provide clocking for the
entire network. To prevent data transmission errors caused by clock differentials throughout a
synchronous network, a 8 bit ring buffer is provided. In applications where the master port and the
selected port provide their own clocks, data is clocked into the buffer at the receive clock rate of the
active port and clocked out using the master port transmit clock.
In applications where the Clear To Send(CTS) control signal is not provided by the master port, an
option for forced CTS is available via 3-position stick headers. Additionally, several user defined
RTS/CTS delay settings are available.
The DMM-4DC also provides optional Anti-Streaming circuitry. Once enabled, Anti-Streaming will
automatically remove a defective terminal or modem from service if the Data / Control criteria is present
for the user predefined selection period.
Housed in a sturdy aluminum enclosure and equipped with an internal -48 VDC power supply, the
DMM-4DC will provide in excess of 400,000 hours of reliable service.
DMM-4DC
OPERATIONS MANUAL
Page 1
MASTER
REAR VIEW OF DMM-4DC
GND
FRONT VIEW OF DMM-4DC
PWR
EAST COAST
D A T A C O M, I N C .DMM-4DC
48V
NEG 48V RET
- +
48V
RET
48V
NEG
PORT 1
PORT 2PORT 3
PORT 4
RD
SD 123412 3 4
ACTIVE STREAM
1234
SUB-CHANNEL STATUS
ENABLE
DISABLE

Located on the rear panel of the product are the RS-232 user data ports and the -48VDC input
connector.
2.3 CLOCKING, INTERNAL AND EXTERNAL
Three modes of clocking are available to the DMM-4DC user.
1) Clocking may be set as Internal Timing utilizing the internal Baud Rate Generator.(JP5,
connect 1 and 2)
2) Clocking may be set as External Timing utilizing a DCE device attached to the Master Port
.(JP5, connect 2 and 3)
3) Clocking may be set as Telco Timing from an attached DCE via Port 1 .(JP5, connect 2 and 4)
Internal Timing mode will facilitate user defined operational speeds from 450bps to 76.8Kbps.
Networks such as 56/64k DDS (Digital Circuits) should be timed via Port 1.
A Green LED illuminates when DC Power has been applied. Two adjacent Green LEDs
illuminate in union with individual Green subchannel port activity LEDs and identify Transmit
and Receive data transmissions. Yellow LEDs provide the user with a visual indication of a
streaming DTE (ref. 2.6) Positive latching switches are provided for each DTE port for isolating
or removing a streaming terminal. Each DTE port has its own switch and operates
independently. To disable a subchannel, simply push the switch. A channel is disabled when the
switch is in the outer most position.
2.2 REAR PANEL CONNECTORS
CHAPTER 2 - BASIC OPERATION
2.1 FRONT PANEL INDICATORS AND SWITCHES
1.2 THEORY OF OPERATION
The DMM-4DC allows up to four DCEs or DTEs to share one DCE or DTE communications
link. In a broadcast, polled or contention environment, the typical DMM-4DC operation is as
follows:
Data arriving at the DMM-4DC's master port is continually broadcast to all subchannel ports.
When one of attached DCE or DTE devices answers a poll from the host site, that device will
raise RTS (Request To Send for terminals) or DCD (Data Carrier Detect for modems). When
RTS or DCD is raised, the DMM-4DC will lock on to that port and allow that device to
communicate to the Host Site. The DMM-4DC will remain locked onto that port until RTS or
DCD is dropped. After RTS or DCD has dropped, the DMM-4DC will automatically begin
scanning the ports until another port raises RTS or DCD.
DMM-4DC
OPERATIONS MANUAL
Page 2

2.4 RS-232 ELECTRICAL INTERFACE
The DMM-4DC user data ports are EIA RS-232 compliant, utilizing female DB-25 connectors.
Refer to the interface chart in the Appendix for detailed interface information. The maximum
data rate is 128kbps. The unit incorporates surge protection on each RS-232 data port.
2.5 SUBCHANNEL SERVICE MODES
The DMM-4DC incorporates circuitry that enables the user to scan each sub-channel port.
2.5.1 SUBCHANNEL SCANNING
Subchannel Scanning will allow equal access to the communications link for all connected DCE
or DTE devices. The subchannels are scanned in sequence (1 - 2 - 3 - 4) and the attached
subchannel DCE that raises DCD or DTE that raises RTS will have access to the
communications link. After dropping RTS the DMM-4DC will continue scanning in sequential
order.
2.5.2 SUBCHANNEL RTS TO CTS DELAY
RTS to CTS delays of 0, 5, 10 and 20ms are user selectable.
2.6 ANTI-STREAMING
2.6.1 AUTOMATIC DTE REMOVAL
The DMM-4DC incorporates circuitry that will (when enabled) automatically remove a
streaming DCE or DTE from service. A streaming terminal is defined as a terminal that has RTS
high longer than the user predefined anti-stream timer has been set. Upon installation, the user
can set or actually fine tune the timer to your network requirements. Each channel has a Green
and a Yellow LED to indicate subchannel activity. Green indicates an active subchannel and
Yellow indicates a streaming subchannel. Once a terminal has gone into the streaming condition
(RTS continually high) the DTE will automatically be removed from service until the DTE fault
has been corrected by the user. All other DTE's will continue to be serviced.
2.7 SYNC AND ASYNC SELECTION
The DMM-4DC incorporates circuitry that allows the user to select Synchronous or
Asynchronous operation.
DMM-4DC OPERATIONS MANUAL
Page 3

2.10 CASCADING OR CONCATENATION
The DMM-4DC supports cascading by utilizing DB-25 Male-to-Male straight through shielded
cables. Subchannel Port 1 should be used as the concatenation port.
2.8 MANUAL DTE/DCE REMOVAL
The DMM-4DC incorporates circuitry that will (when enabled) manually remove a streaming
terminal from service. A streaming terminal is defined as a terminal that has RTS continually
high. With Anti-streaming disabled, the associated streaming DTE will NOT illuminate a
Yellow LED on the front of the MSD. If the automatic anti-streaming circuitry is disabled and a
streaming condition occurs, the other DTE devices will be blocked from accessing the
communications link. To correct this condition, simply push the associated push-button switch
for the subchannel that is streaming. All other DTE's will now continue to be serviced by the
DMM-4DC. However, you still need to fix the offending DTE or DCE device that has RTS or
DCD continually raised.
2.9 UNEXPLAINED STREAMING TERMINALS
Many different types of terminals have been manufactured over the years. A typical problem is
unexplained lockup or lockout problems. The most common cause is when, four terminals are
running just fine and when one of the terminals is powered down, the remaining terminals are
locked out of service. This may be explained by a missing or incorrect Termination Resistor that
has been overlooked by your terminal manufacturer. This is the main reason that Anti-Streaming
circuitry has been designed into the DMM-4DC and we encourage the user to take advantage of
this feature. An additional feature is a 4.7k Pull Down resistor tied to the RTS or DCD control
leads.
DMM-4DC OPERATIONS MANUAL
Page 4
D
M
M
D
M
M
MODEM
CONNECT TO MASTER PORT
CONNECT TO PORT 1
DB-25 CABLE
CASCADING DIAGRAM
OR F.E.P.

2.12 NORMAL OR FORCED CLEAR TO SEND (CTS) (PORTS 1 - 4)
The DMM-4DC has internal jumpers(JP1-JP4) for Normal or Forced Clear To Send (CTS).This
option will allow attached sub-channel devices that do not receive CTS control signals from the
attached DMM-4DC Master Port to have CTS selectively Forced High to the attached
sub-channel device. To Force CTS, move the jumper so that both headers are connected on
positions 2 and 3.
2.13 DCE / DTE SWITCHES
Located internally are five sets of two (2) DCE/DTE slide switches located in front of each
RS-232 port. Silkscreened on the Printed Wiring Board are DCE and DTE. Slide BOTH
switches to the same position to configure each of the RS-232 ports as a DTE or a DCE interface.
When set to DCE, the RS-232 port MUST connect to a DTE device.
When set to a DTE, the RS-232 port MUST connect to a DCE device.
2.11 ENABLE CONTROL (PORTS 1 - 4)
The DMM-4DC has internal jumpers(JP6-JP9) for Enable Control.This option will allow
attached sub-channel devices that do not respond to RTS or DCD control signals. This option
will monitor Transmit Data (TXD). When data is present, the DMM-4DC will lock onto the
attached subchannel device. To Enable Control, move the jumper so that both headers are
connected on positions 1 and 2.
DMM-4DC OPERATIONS MANUAL
Page 5
DCE
DTE
ENABLE CONTROL(1,2)
JP6
(PORT 1)
1
2
3
DISABLE CONTROL(2,3)
JP1
(PORT 1)
NORMAL CTS(1,2)
FORCED CTS(2,3)
1
2
3

Power Connection
Figure 3-1
CHAPTER 3 - INSTALLATION
3.1 INPUT VOLTAGE
The DMM-4DC is designed to accept DC voltages of 36 to 72 vdc, with 48 vdc as the nominal
input voltage. Located on the back of the DMM-4DC is a 2-position terminal block. The block is
removable and accepts a small slotted screwdriver to fasten the users DC voltage wires. The wire
strip length should be 7mm or .24 inches.
3.2 VOLTAGE FUSES
The DMM-4DC is designed with internal safety fuses for your protection. Located inside the
product are two 315ma slow blow 5 x 20mm fuses. If the power LED is not illuminated,
disconnect the input DC power source, remove the top cover and inspect the fuses. Spare fuses
may be obtained by calling East Coast Datacom Replacement fuse Part # 714003 or by calling:
Little Fuse at [phone], Part # 218.315
Shurter, Inc. at [phone], Part # 034.3112
Panel Components [phone], Part # 81412321
3.3 POWER/GROUND CONNECTION
Before connecting the DMM-4DC to a DC power source the top cover MUST be installed with
the supplied #8-32 screws.
1) Connect the ground lead to the #6 stud located on the rear of the DMM-4DC marked GND
(ground)
2) Connect the -48V wire to the termial block labeled 48V NEG.
3) Connect the 48V RTN (return or +) wire to the termial block labeled 48V RTN.
DMM-4DC
OPERATIONS MANUAL
Page 6
CAUTION: Disconnect Power Before Servicing
ATTENTION: Couper Le Courant Avant l' Entretien
VORSICHT: Befor Deckung Abnehmen Mach Strom Zu
MASTER
GND
48V
NEG 48V RET
- +
GND
48V
NEG 48V
RET
DMM-4DC - REAR VIEW

3.4 DEFAULT CONFIGURATION SWITCH SETTINGS
The DMM-4DC is configured prior to shipping with the Internal Switches set as follows:
1) Master Port - DCE
2) Sub-channel Ports - DTE
3) Timing - Internal
4) CTS, Ports 1 through 4 - Normal
5) Enable Control, Ports 1 through 4 - Disabled
6) CTS Delay - 0ms
7) Anti-Streaming - Disabled
8) Clock Select - 9600
9) Async/Sync Selection - Sync
If your system application requires one or more of the default settings to be changed, it will be
necessary to remove the top cover of the DMM-4DC. Remove the DC Power source or
Disconnect the DC Power before servicing the unit. Removal of the top cover is accomplished
by using a small Philips screwdriver and removing the outside screws. After setting the switches,
replace the top cover before applying DC power.
3.5 MODEM (DCE) AND TERMINAL (DTE) CONNECTION
Before applying DC Power to the unit, the DCE and DTE cabling should be connected. Straight
through Male-to-Male DB-25 shielded cables should be utilized.
DMM-4DC OPERATIONS MANUAL
Page 7

4.0 - APPENDIX
4.1 EIA INTERFACE CHART
EIA RS-232-D INTERFACE CHART (DB-25 CONNECTOR)
XExternal TimingDA11324
XTerminal ReadyCD108.220
XReceive TimingDD11517
XSend TimingDB11415
- Voltage(-9v)10
+ Voltage(+9v)9
XReceive Line DetectorCF109
------Signal GroundAB1027
XDCE ReadyCC1076
XClear To SendCB1065
XRequest To SendCA1054
XReceive DataBB1043
XSend DataBA1032
------Shield------1
To DCETo DTESignal DescriptionCircuit
Name
CCITT
Circuit No.
Pin No.
DMM-4DC OPERATIONS MANUAL
Page 8

4.2 FACTORY DEFAULT CHART
DMM-4DC OPERATIONS MANUAL
Page 9
MASTER PORT
DCE DTE
PWR
TXD
RXD
ON
1 2 3 4 5 6 7 8
SW9 SW10
FULL BAUD RATE SELECT
SW11 76800 38400 19200 9600 4800 2400 1200 600
5 ON OFF ON OFF ON OFF ON OFF
6 ON ON OFF OFF ON ON OFF OFF
7 ON ON ON ON OFF OFF OFF OFF
ASYNC / SYNC SELECTION
SW11 ASYNC SYNC
9 ON OFF
NOT USED
SW11 RESERVED FOR FUTURE USE
10
RTS/ CTS DELAY SW11 0 MS 5 MS 10 MS 20 MS
1 ON ON OFF OFF
ANTI-STREAM
2 ON OFF ON OFF
SW11 DISABLE 5 SEC. 10 SEC. 60 SEC.
3 ON ON OFF OFF
4 ON OFF ON OFF
INT. TIMING(1,2)
48V RTN(+)
PORT 1
DCE DTE
SW1 SW2
PORT 2
DCE DTE
SW3 SW4
PORT 3
DCE DTE
SW5 SW6
PORT 4
DCE DTE
SW7 SW8
910
8 OFF OFF OFF OFF OFF OFF OFF OFF
3/4 BAUD RATE SELECT
SW11 57600 28800 14400 7200 3600 1800 900 450
5 ON OFF ON OFF ON OFF ON OFF
6 ON ON OFF OFF ON ON OFF OFF
7 ON ON ON ON OFF OFF OFF OFF
8 ON ON ON ON ON ON ON ON
ACTIVE
INDICATORS STREAM
INDICATORS
SUB-CHANNEL
ENABLE / DISABLE
SWITCHES
EXT. TIMING(2,3) JP1 (PORT 1)
JP5 NORMAL CTS
FORCED CTS
ENABLE CONTROL(1,2)
JP2(PORT 2)
NORMAL CTS FORCED CTS
JP3 (PORT 3)
NORMAL CTS FORCED CTS
JP4(PORT 4)
NORMAL CTS FORCED CTS
S11
** BOLD TEXT DENOTES FACTORY DEFAULT
DMM-4DC FACTORY DEFAULT / SWITCH GUIDE
PORT 1 TELCO TIMING(2,4)
JP9 (PORT 4)
JP6 (PORT 1) JP7 (PORT 2) JP8 (PORT 3) 1
2 3
1 2 3
1 2 3
1 2 3
1 2 3
1 2 3
1 2 3
1 2 3
1 2 34
DISABLE CONTROL(2,3)
ENABLE CONTROL(1,2)
DISABLE CONTROL(2,3) ENABLE CONTROL(1,2)
DISABLE CONTROL(2,3)
ENABLE CONTROL(1,2)
DISABLE CONTROL(2,3)
48V NEG(-) 315 ma FUSE
315 ma FUSE
F1
F2
48V NEG(-)
48V RTN(+)
J6

4.3 CLOCKING / APPLICATION DIAGRAM
DMM-4DC OPERATIONS MANUAL
Page 10
4 RTS
5 CTS
3 RX DATA
17 RX CLOCK
15 TX CLOCK
2 TX DATA
6 DSR
CONTROL
AND
BUFFER
INTERNAL
TIMING
8 DCD
9 + TEST
10 - TEST
20 DTR
24 X TX CLOCK
+12
+12
+12
+12
+12
-12
DCD 8
RX DATA 3
RX CLOCK 17
TX CLOCK 15
X TX CLOCK 24
TX DATA 2
RTS 4
DTR 20
CTS 5
DSR 6
TERMINAL HOST
CONNECTED TO
DMM-4, MASTER PORT DMM-4
MODEM
CONNECTED TO
DMM-4, PORT 1
MODEM 2
MODEM 3
MODEM 4
SET TO: EXTERNAL TRANSMIT CLOCK
(TERMINAL TIMING)
MODEM
(SLAVE)
SET TO: RECEIVE CLOCK
(SLAVE CLOCK)
DMM-4 CLOCKING AND SIGNAL ROUTING DIAGRAM
CSU/DSU
TERMINAL
TERMINAL
DIGITAL MIXING
MODULE, DMM-4
TERMINAL
TERMINAL
DIGITAL
MIXING
MODULE
DMM-4
HOST
CPU
EAST
COAST
DATACOM
DME, SYNC
LINE DRIVER DME, SYNC
LINE DRIVER
TERMINAL
DME, SYNC
LINE DRIVER DME, SYNC
LINE DRIVER
TERMINAL
PRIVATE 4-WIRE
PRIVATE 4-WIRE
DMM-4DC APPLICATION DIAGRAM
EAST COAST DATACOM, INC.
TEL: [phone] OR [phone]
WWW.ECDATA.COM
CSU/DSU
CSU/DSU
CSU/DSU
CSU/DSU
CSU/DSU
CSU/DSU
CSU/DSU
TERMINAL
DMM-4DC

4.4 USER NOTES:
DMM-4DC OPERATIONS MANUAL
Page 11

4.5 TECHNICAL SPECIFICATIONS
Application
Multiple Sync/Async DCE/DTE devices operating
in a polled or contention environment, to share one
DCE/DTE port
Capacity
Main Input: One RS-232 Port
Subchannel Ports: One to Four RS-232
Sync/Async devices
Interface
EIA RS-232-D, CCITT V.24 using DB-25 female
connectors, selectable as DCE or DTE interface
Data Rates
Internal Select: 450bps to 76.8Kbps
External: Up to 128Kbps
Data Format
Data transparent at all data rates
Timing Options
Internal
External: via Input Master Port
External: Telco Timing via Port 1
Anti-Streaming
Automatic: Selectable timeout intervals
Disable: Selectable via dip switch
Terminal Service Modes
Sequential scanning for RTS or DCD control
signal, option for switch on RXD Data(JP6-JP9)
Clear To Send
Allows normal RTS/CTS handshaking or has
option for Forced CTS on Ports 1-4 (JP1-JP4)
RTS To CTS Delay
Selectable RTS to CTS delays of 0, 5, 10 and 20ms
Front Panel
Indicators: Power, Transmit Data, Receive Data,
Channel Active, Channel Stream
Switches: Enable/Disable of each Sub-channel
Power Source
DC Voltage, Input Range of 36 to 72vdc
Current Draw at 48vdc: 75ma @ 3.6watts
Safety Approvals
C-UL 60950, CE Safety EN60950 and CE EMC
EN300-386-2
Environmental
Operating Temperature:
32º to 122º F (0ºto 50º C)
Relative Humidity:
5 to 95% Non-Condensing
Altitude:
0 to 10,000 feet
Dimensions
DMM-4DC
Height: 1.75 inches (4.44 cm)
Width: 17.00 inches (43.18 cm)
Length: 9.00 inches (22.86 cm)
Weight
4.5 pounds (2.1Kg)
Warranty
Three Years, Return To Factory
ORDERING INFORMATION
Part Number: 162000
Model: DMM-4DC
Description: RS-232 Digital Mixing Module
INCLUDED WITH EACH UNIT:
1) Operations Manual
2) Rackmount Kit
OPTIONAL ACCESSORIES
315ma Fuse, Qty (2) Part # 714004
DMM-4DC OPERATIONS MANUAL
Page 12