DCB SRX Multidrop User manual

8500026
SRX Multidrop
TABLE OF CONTENTS
SECTION 1 - DESCRIPTION.......................................................................2
SECTION 2 - SPECIFICATIONS .................................................................4
SECTION 3 - INSTALLATION.....................................................................6
SECTION 4 - FRONT PANEL CONTROLS AND INDICATORS................9
SECTION 5 - NETWORK MANAGEMENT PORT....................................13
SECTION 6 - INTERFACE SIGNALS AND CABLING..............................23
SECTION 7 - TROUBLESHOOTING.........................................................29
SECTION 8 - WARRANTY.........................................................................32
APPENDIX - MULTIDROP MAP WORKSHEET......................................33
Data Comm for Business, Inc.
PO Box 6329
Champaign, IL 61826-6329 August 8, 2002
[phone] Firmware Version: 16.51 / 32.51
www.dcbnet.com

2
1.DESCRIPTION
General
The DCB multidrop multiplexer configuration uses an SRX platform at
the host location (called HOST) and an SPL platform for remote units
(called DROPs). The objective of this multidrop configuration is to
provide reasonable performance at the remote sites in those applications
where a dedicated line from the host is not cost justified. Using high
speed digital multidrop service, many distributed site applications can
benefit from this configuration.
Performance
The SRX provides excellent performance for asynchronous interactive
terminals when using multidrop digital lines, especially at a composite
speed of 128 Kbps. The SRX multidrop is engineered to provide a
quarter second or less echo time in typical configurations. This short
echo time gives each terminal the appearance of direct connection to its
computer port.
Single Host Configuration
The SRX multidrop host multiplexer can have up to 32 ports in
increments of 8 ports. Network configuration is set from the front panel
LCD display or via the Network Management port. Network
configuration (mapping) is determined solely by the host multiplexer.
Each host port is mapped internally to a drop port and the host
multiplexer handles all translation between host and drop port
numbers.
Multiple Host Configuration
The SRX multidrop firmware also allows the host site to expand to more
than a single SRX host. Multiple SRX hosts share the line using an
MSU-4 modem sharing unit. A maximum of 64 ports is recommended
to maintain satisfactory performance.
Configuration Planning
The network configuration must be mapped before the system will
operate. If no host port is assigned to a particular drop, that drop is not
polled for input. Host ports must be mapped to drop ports before those
drop ports become active. For this reason, some amount of planning is
necessary before implementing a multidrop network.

3
The network and port configurations are stored in battery backed RAM
to survive power failures. To reset all ports to the factory defaults and
clear all local IDs and port mappings, press and hold the OK! switch
while pressing RESET.
OPTION
MODEM READY
LINE ERROR
ACTIVITY
POWER
NEXT
INCR
-->
OK!
SRX 8/16 MULTIPLEXER
DCB
SRX Host Multiplexer, 8 and 16 Channels

4
2. SPECIFICATIONS
2.1 Product
2.1.1 Data Ports
Port Speeds
Asynchronous only
300, 1200, 2400, 4800, 9600, 19,200 or 38,400 bps
Data Format
10 bits/character, 1 start, 1 stop, 8 data (including parity)
Interface
RS-232D, implemented in RJ-45, 8 position connectors
2.1.2 Composite Port
Speed
Synchronous to 128 Kbps
Asynchronous at 1200, 2400, 4800, 9600, 19,200 or 38,400 bps
Interface
RS-232D, implemented in RJ-45, 8 position connector
2.2 Environmental
Operation: 0 to 65° C, 10 to 85% relative humidity
Storage: -40 to 85° C, 10 to 85% relative humidity
2.3 Physical / Electrical
10¼" W x 9¾" D x 2½" H - 8 and 16 channel units
10¼" W x 9¾" D x 4¼" H - 24 and 32 channel units
120 VAC external power supply
30 watts, .25 amps

5
2.4 Network Management Port Commands
Show Configuration
Show ID
Show Map
Show Drop Map
Show Network Configuration
Show Status
Change Configuration
Change ID
Change Map
Change Network Configuration
Change Restart Timer
Activity Counts
Drop Activity
Zero Activity Counts
Flow Control
Test Tools
Capture Port
Copy Command
Show RS232
Test Message
Remote Test Loop
Monitor Port TX
Monitor Port RX
NM Parity
Drop History
Drop Restart
Kill Drop
Suspend Drop
Poll ALL Drops
Port Reset
Reset Mux
Type
Repeat Last Command
Disconnect NMP

6
3. INSTALLATION
3.1 Unpacking
The following is included with each SRX Multiplexer:
•Multiplexer and external power supply
OPTION
MODEM READY
LINE ERROR
ACTIVITY
POWER
NEXT
INCR OK!
SRX 8/16 MULTIPLEXER
DCB
•Cables for connecting a modem or DSU/CSU and a Network
Management terminal.
•Manual
SPL 2 TO 14 CHANNEL
STATISTICAL
MULTIPLEXER
DCB PRODUCT MANUAL
DCB
•Information regarding warranty, maintenance contracts and repair
If a multiple host system was ordered, additional equipment is supplied.
•Modem Sharing Unit (one for each combination of Host multiplexers
up to a recommended total of 64 ports)
•Male to female RS-232 cable (one per MSU)
CHANNEL 1 CHANNEL 2 CHANNEL 3 CHANNEL 4COMMON MSU 4D

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3.2 Location
Place the multiplexer in a clear area where you can reach the front
panel for setup and the rear panel to connect the cables. The
multiplexer has an external power supply that requires a properly
grounded 120 VAC outlet. The total power cord length is about 12 feet.
3.3 Setup
Setup of the SRX Host Multiplexer can be done using the front panel
controls and LCD display or by using a terminal connected to the
Network Management port. Front panel operation is covered in Section
4, the Network Management port is discussed in Section 5.
3.4 Connections
3.4.1 Single Host
Connection to the host modem or DSU/CSU is made using the supplied
“Modem to Composite” cable. The host modem or DSU/CSU should be
set for constant carrier operation (RTS forced ON). For information
regarding host computer port connections, see Section 6.
D CB DSU/CSU 56
INSDCD RTSCTS TxD RxD SELF
TESTDIGITAL LOOP
LOCAL
LOOP
REMOTE
TEST SELECT
OPTION
MODEM READY
LINE ERROR
ACTIVITY
POWER
NEXT
INCR OK!
SRX 8/16 MULTIPLEXER
DCB
To Telco
Modem/DSU
SRX
Host
See Section 6 Modem to Composite Cable

8
3.4.2 Multiple Host
The multiple host configuration allows more than one host multiplexer
to be connected to the multidrop line. This requires a Modem Sharing
Unit. The SRX Host multiplexers are connected to the MSU ports
using the “Modem to Composite” cable. The MSU is connected to the
Modem or DSU/CSU using the male to female RS-232 cable. The
modem or DSU/CSU should be set for constant carrier operation (RTS
forced ON). For information regarding host computer port connections,
see Section 6.
DCB DSU/CSU 56
INSDCDRTSCTSTxDRxD SELF
TEST
DIGITAL
LOOP
LOCAL
LOOP
REMOTE
TEST SELECT
OPTION
MODEM READY
LINE ERROR
ACTIVITY
POWER
NEXT
INCR OK!
SRX 8/16 MULTIPLEXER
DC B
OPTION
MODEMREADY
LINEERROR
ACTIVITY
POWER
NEXT
INCR
OK!
SRX 8/16 MULTIPLEXER
D
C
B
BPV
CARRIER LOSS
FRAME ERROR
SYNC LOSS
POWER
NEXT
INCROK!
T-DRIVER
D
C
B
RESET
Host SRX
SRX
Modem/DSU
See Section 6
Modem to Composite Cable
Ribbon Cable
Modem
Sharing Unit
3.5 Installation Summary
1. Set the host modem or DSU/CSU for constant carrier operation.
(RTS forced ON)
2. Connect the host modem or DSU/CSU to the phone line. If this
is a multiple host installation, connect the Modem Sharing Unit
composite port to the modem or DSU/CSU.
3. Configure the host SRX multiplexer(s).
a. Map at least one port to each drop to be installed.
b. Configure the SRX ports for correct speed, parity and flow
control.
c. Connect the SRX to modem or DSU/CSU using the Modem to
Composite cable supplied. If this is a multiple host
installation, connect the SRXs to the Modem Sharing Unit.
d. Connect a properly configured CPU port to each mapped SRX
port. See Section 6 for host port cabling information.
4. Go to each remote site and follow the steps in Section 3.5 of the
SPL Multidrop manual.

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4. FRONT PANEL CONTROLS AND INDICATORS
4.1 Controls
4.1.1 Keys
The NEXT key is used to cycle between top level displays.
The ARROW key (→) moves the cursor to the next parameter field.
The INCR key is used to cycle through the various options available.
The OK! key is pressed to accept the selected value or to enable or
disable the selected test.
OPTION
MODEM READY
LINE ERROR
ACTIVITY
POWER
NEXT
INCR
-->
OK!
SRX 8/16 MULTIPLEXER
DCB
Front Panel Layout
4.1.2 Display Tree
Use the NEXT key to go between these displays.
Home
MAP Host Port
ConFiGure (single port)
ConFiGure All (ports)
TEST Msg
NETwork (activity)
DRoP(activity)
FLOW (port)

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Home Display
The HOME display is the SRX default display. It shows the product
name and the number of ports. Pressing the Arrow key will display
firmware version information. Press Arrow again to return to the home
display.
MAP Host Port
The MAP Host Port screen shows the mapping between the local port
numbers and remote port numbers. As each local port is selected, the
corresponding remote drop and port numbers are listed on the lower
line. If the port is not mapped, dashes (--) will be displayed.
Instructions for changing settings are contained in Section 4.1.3.
Configure Port Parameters
The CFG screen selects the port configuration parameters for either
local or remote ports one port at a time. Both local and remote
configurations are referenced to the local (host) port number.
Configurable parameters include port loopback (LP/OFF), flow control
and speed.
Configure All Port Parameters
The CFG All screen selects the port configuration parameters for all
local or remote ports. Configurable parameters include port loopback,
flow control and speed. The default parameters are; loop off, flow control
Xon/Xoff, Space parity and 9600 bps.
Test Message
The TEST Msg screen transmits a Quick Brown Fox (QBF) message to
any local or remote port. All port numbers refer to local (host) ports.
Once the desired port is selected, the OK! key starts the test. A 15
minute timer begins on the far right side of the display. The test
continues until any front panel key is pressed or for 15 minutes,
whichever happens first.
Network Activity
The NETwork activity display shows the number of data blocks sent
and received for all drops. The INCR key toggles this display between
the block count and the error count.