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FCC NOTICE: The equipment described in this manual generates, uses, and may emit
radio frequency energy. The equipment has been type tested and found to comply with
the limits for a Class A computing device pursuant to Subpart J of Part 15 of FCC
Rules, which are designed to provide reasonable protection against such radio frequency
interference when operated in a commercial environment. Operation of this equipment in
a residential area may cause interference, in which case the user at his own expense may
be required to take measures to correct the interference.

This equipment is in the First Class category (information equipment to be used in
commercial and/or industrial areas) and conforms to the standards set by the Voluntary
Control Council for Interference by Data Processing Equipment and Electronic Office
Machines aimed at preventing radio interference in commercial and/or industrial areas.
Consequently, when used in a residential area or in an adjacent area thereto, interference
may be caused to radios, TV receivers, etc. Read the instructions for correct handling.

MA-0347-90-CPG.DG

This document was prepared and published by Educational Services Development and
Publishing, Digital Equipment Corporation.

DECrepeater 350
Service Guide
Order Number EK–DETPR–SV–001

Digital Equipment Corporation

First Edition, October 1990
The information in this document is subject to change without notice and should not
be construed as a commitment by Digital Equipment Corporation. Digital Equipment
Corporation assumes no responsibility for any errors that may appear in this document.
The software described in this document is furnished under a license and may be used or
copied only in accordance with the terms of such license.
No responsibility is assumed for the use or reliability of software on equipment that is not
supplied by Digital Equipment Corporation or its affiliated companies.
Restricted Rights: Use, duplication, or disclosure by the U. S. Government is subject to
restrictions as set forth in subparagraph ( c ) ( 1 ) ( ii ) of the Rights in Technical Data and
Computer Software clause at DFARS 252.227–7013.
Copyright © Digital Equipment Corporation 1990
All Rights Reserved.
Printed in U.S.A.
The following are trademarks of Digital Equipment Corporation:
DEC
DECconnect
DECmate
DECnet
DECrepeater
DECUS
DECwriter
DELNI
DEMPR

DESTA
DIBOL
MASSBUS
PDP
P/OS
Professional
Rainbow
RSTS

RSX
RT
ULTRIX
UNIBUS
VAX
VMS
VT
Work Processor

AT&T is a trademark of the American Telephone and Telegraph Company.
IBM is a trademark of the International Business Machines Corporation.
This document was prepared and published by Educational Services Development and
Publishing, Digital Equipment Corporation.

Contents
About This Guide
1

DECrepeater 350 Overview

DECrepeater 350 Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Twisted-Pair Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1
2

Functional Description

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Data Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chip Data Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Receiver Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmit Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Collision Enforcement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Segmentation of Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

vii

3
5
5
5
6
6
6

Configuration Rules

DETPR Configuration Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . .
Station Equipment Connection Guidelines . . . . . . . . . . . . . . . . . . . .
DELNI/DETPR Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ethernet Pyramid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Standalone Pyramid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System Constraints and Guidelines . . . . . . . . . . . . . . . . . . . . . . . . .
Twisted-Pair Wire Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Twisted-Pair Ethernet Restrictions . . . . . . . . . . . . . . . . . . . . . . .

8
8
9
9
9
9
10
10

iii

iv Contents

Troubleshooting

Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Internal Power-Up Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
External Self-Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
How These Tests Differ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Standalone or Network Testing . . . . . . . . . . . . . . . . . . . . . . . . . .
DETPR Control Panel Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . .
Problem Solving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power-Up Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Self-Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Test with Station Equipment Connected to DETPR . . . . . . . . . . .
Test with Ethernet Connected . . . . . . . . . . . . . . . . . . . . . . . . . . .
Crossover Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Isolating Cable Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12
12
12
13
13
14
15
15
16
17
18
19
20

DETPR Specifications

Physical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AC Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DC Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Environmental Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Relative Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Part Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cable Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unshielded Twisted-Pair Cable Requirements . . . . . . . . . . . . . . .
Unshielded Twisted-Pair Cable Environmental Constraints . . . .
Connector Pinouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-Pin MJ Connector (Ports 1 to 8) . . . . . . . . . . . . . . . . . . . . . . . .
15-Pin D Connector (Port 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

22
22
22
23
23
23
23
23
24
24
25
25
26
26
26

Contents v

Figures
1–1
2–1
4–1

DECrepeater 350 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DETPR Functional Block Diagram . . . . . . . . . . . . . . . . . . . .
DETPR Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1
4
14

Tables
4–1
4–2
4–3
4–4
4–5
4–6
4–7

Control Panel Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power-Up Test Troubleshooting . . . . . . . . . . . . . . . . . . . . . . .
Self-Test Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DETPR-to-Station Equipment Test Troubleshooting . . . . . . .
Ethernet Test Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . .
Crossover Test Troubleshooting . . . . . . . . . . . . . . . . . . . . . . .
DETPR and H3350 Twisted-Pair Cable Fault Isolation . . . . .

14
15
16
17
18
19
20

About This Guide
This manual provides a functional overview, configuration guidelines,
troubleshooting information, and specifications for the DECrepeater
350 signal repeater. The DECrepeater 350 is also known as the Digital
Ethernet twisted-pair multiport repeater (DETPR). It can connect eight
node devices to a standard Ethernet backbone network. The DECrepeater
350 uses twisted-pair cable to transmit Ethernet signals between itself
and the eight nodes.
The DECrepeater 350 is available in four versions:
Model

Version

Description

DECrepeater

Desktop, plastic enclosure

120 V

DECrepeater

Desktop, plastic enclosure

220 V

DECrepeater

Rackmount, aluminum box

120 V

DECrepeater

Rackmount, aluminum box

220 V

Organization
This guide has four chapters and one appendix.
•

Chapter 1 gives an overview of the DECrepeater 350 unit and an
introduction to twisted-pair wiring.

•

Chapter 2 gives a functional overview of the DECrepeater 350.

•

Chapter 3 describes configuration rules and guidelines for installing
and using the DECrepeater 350.

•

Chapter 4 provides troubleshooting information for use when servicing
the DECrepeater 350.

•

Appendix A lists specifications, environmental constraints, and
connector pinouts.

vii

viii About This Guide

Related Documents
You can order the following documents from Digital:
Document

Order Number

Network and Communications Buyer’s Guide

EC–I0391–42

DECconnect System General Description

EK–DECSY–GD

DECconnect System Requirements Evaluation Workbook

EK–DECSY–EG

DECconnect System Planning and Configuration Guide

EK–DECSY–CG

DECconnect System Installation Verification Guide

EK–DECSY–VG

Installing and Using the DECrepeater 350

EK–DETPR–IN

H3350 Transceiver Installation

EK–H3350–IN

Ordering Information
Customers may order documents by phone or mail.
Continental USA and Puerto Rico Call 800–258–1710 or mail to:

Digital Equipment Corporation
Peripherals and Supplies Group
P.O. Box CS2008
Nashua, NH 03061
New Hampshire, Alaska, and Hawaii Call 1–603–884-6660.
Outside the USA and Puerto Rico Mail to:

Digital Equipment Corporation
Attn: Accessories and Supplies Business Manager
c/o Local Subsidiary or Digital-Approved Distributor
Digital Personnel Digital personnel may order these documents from:

Digital Equipment Corporation
444 Whitney Street
Northboro, MA 01532
Attn: Publishing and Circulation Services (NRO3/W3)
Order Processing Section

1
DECrepeater 350 Overview
This chapter provides an overview of the DECrepeater 350 (DETPR)
signal repeater and twisted-pair technology.

DECrepeater 350 Unit
The DETPR is an ac-powered signal repeater that has eight twisted-pair
ports and one attachment unit interface (AUI) port (Figure 1–1). The
eight twisted-pair ports (two pairs for each port) use 8-pin modular jack
(MJ) connectors. The AUI port has one 15-pin female D-subminiature
connector to connect to an H4000/H4005 Ethernet transceiver or an IEEE
802.3 medium attachment unit (MAU).
The DETPR treats all of the twisted-pair ports and the AUI port as a
common data bus by way of a gate array. The gate array performs all
arbitration for the use of the ports. The joining of the twisted-pair ports
and the AUI port creates a larger Ethernet. The DETPR passes all data
received from a port to the other eight ports of the unit. The DETPR is
not an Ethernet-addressable unit on the network.

MA-0305-90-CPG.DG

Figure 1–1

DECrepeater 350

2 DECrepeater 350 Overview

Twisted-Pair Technology
A twisted-pair cable consists of two continuous insulated conductors
helically twisted around one another. This wiring normally consists of
0.4 mm to 0.6 mm diameter (26 AWG to 22 AWG) unshielded wire in a
multipair cable. The wire is used as a medium for a Type 10BaseT MAU
and an Ethernet transceiver IEEE AUI cable.
The MAU provides an inexpensive, flexible electrical interface for
attaching devices and stations to a local network medium such as
Ethernet. The MAU is aimed primarily at office applications where
telephone twisted-pair cable is often installed. This type of cable and
connector offers simplicity of installation and reconfiguration.
A repeater unit is used to extend the physical system topology and to
provide coupling for two or more segments. A segment is a medium
used for interconnecting MAUs. This medium includes the medium
dependent interface (MDI), a mechanical and electrical interface between
the twisted-pair cable and the MAU.

2
Functional Description
This chapter provides a brief functional description of the DETPR
repeater.

Overview
The DETPR is used to expand the topology of the Twisted-Pair Ethernet
to the extended Ethernet LAN. The DETPR restores the amplitude and
timing margins as signals are propagated through the unit to the other
ports attached to the DETPR.
The passing of data from one port to eight other ports is not a simple
switching task. The timing differences of the ports require the buffering
of the received data. Collisions on any port on the network are passed
to all of the other ports. The received data is decoded by a single-chip
Manchester encoder/decoder to separate the data and the clock for
the gate array. All packets that are received have the 64-bit preamble
restored as it is repeated to the other ports.
The contention-free operation of the DETPR is as follows:
1. A signal is received and detected on one of the ports.
2. A preamble is sent to all of the other eight ports.
3. The end of the preamble is detected on the receive port, and the
replication of the data to the other ports is begun.
4. The collision-detect input from all other ports is continuously
monitored and enforced at all other ports as collisions occur.
The data path of the DETPR is made up of the TPMAU (T7220) media
dependent interface (MDI) chip, the access unit interface (AUI), the
serial interface adapter (SIA), and a gate array. Figure 2–1 is a simple
functional block diagram of the DETPR.

4 Functional Description

The gate array contains four subsystems to control the flow of data:
•

Chip data path subsystem

•

Control subsystem

•

Automatic partition and reconnection subsystem

•

Self-test subsystem

AUI LOGIC
PORT 0
PORT 0
AUI
DC ISOLATION

RDATA
RX

RECEIVE
MUX

TX
TDATA
−−
|

RDATA

RCLK

RCLK
|

|
TCLK

TX
TDATA

TCLK
|

|
TX

TDATA
|

|
|

−−

RDATA
RX

−−
|
CONTROL
SUBSYSTEM

|
|

AUI LOGIC
PORT 8

−−

|
|

Figure 2–1

XMIT

PORT 8
TWISTED−PAIR
XCVR LOGIC

|
|

RDATA
RX

−−

|
RCV

PORT 1
TWISTED−PAIR
XCVR LOGIC

−−

DATA PATH
SUBSYSTEM

SIA LOGIC

AUI LOGIC
PORT 1

−−

SELF−TEST
SUBSYSTEM

|
AUTO−PARTITION
RECONNECTION
SUBSYSTEM

|
|

TX
TDATA

|
|

GATE ARRAY
−− −− −−

DETPR Functional Block Diagram

−−

Functional Description 5

Data Path
Data is received by the transceiver chip from the twisted-pair wire and
sent to the Manchester decoder. The decoded data is sent to the gate
array, where it is buffered in a first-in/first-out (FIFO) buffer. The
transmit ports are determined, the preamble is regenerated, and the
data is sent to the selected transmit ports.

Chip Data Path
The chip data path is made up of a multiplexer, a FIFO buffer, and a
transmit selector circuit. The function of the data path is to select the
data from the Manchester decoder and send it to the FIFO buffer.
The FIFO buffer is a 32-bit buffer for data received from any of the ports.
It allows for speed differences within the network and holds the data until
the entire 64-bit preamble is regenerated.
The transmit-data selector receives data from the FIFO buffer and
transmits that data to the Manchester encoder.

Receiver Function
The receiver function consists of a twisted-pair wire or a D-subminiature
connector, a transceiver and AUI logic, a receive-data and receive-clock
multiplexer, a Manchester decoder (SIA logic), and the FIFO buffer in the
gate array. The receive function works as follows:
1. The transceiver and AUI logic for a twisted-pair port, or the AUI
port (0) with an attached transceiver, detects carrier and collision
information.
2. The carrier and collision information is filtered and sent to the gate
array. This information is used to determine the receive port and to
select the transmit ports.
3. The receive channel is determined and its data input is selected.
4. The SIA logic decodes data encoded by the Manchester encoder and
sends it to the gate array.
5. The data is buffered in a FIFO buffer and held until the entire
preamble is sent to the eight transmitting ports.
6. The receive data is sent to the eight transmitting ports.

6 Functional Description

Transmit Function
The transmit logic uses a Manchester encoder that accepts data from
the chip data path, encodes it to the Manchester format, and transmits
that data to the selected transmit ports. The transmit function works as
follows:
1. The gate array sends the regenerated preamble and data to the SIA
logic.
2. The SIA logic encodes the data in the Manchester format.
3. The SIA logic sends the encoded data to the AUI logic.
4. The AUI logic sends the data to the selected transmit port
transceivers or to the AUI port.

Collision Enforcement
On transmission, the DETPR monitors for collisions and logical (link)
integrity faults on each port. When a collision is detected on a transmit
port, the DETPR jams all other ports according to the mode of operation
(that is, 802.3 96-bit JAM). The JAM continues until the proper amount
of JAM bits have been sent and the collision has stopped. In the case of
a received collision, the DETPR enters the JAM mode on all other ports
except for the port that received the collision. After the JAM has timed
out, the DETPR waits for a specified amount of time as determined by the
selected mode.

Segmentation of Circuits
Segmentation is the removal of a port from active repeating. The use of
segmentation increases the availability of the network. The segmentation
of a port occurs when a fault is detected on the DETPR port. After a port
is segmented, data received by the port is not repeated to any other ports.
However, the faulty port continues to transmit data in order to verify that
it is still faulty. This mode of operation is known as segmentation.
The DETPR restores a segmented port when a reception or transmission
is completed without errors. By definition, an error-free reception has
(1) no detected collisions, and (2) a minimum of 512-bit times without a
logical (link) integrity fault.

Functional Description 7

The DETPR segments a port for the following conditions:
Excessive Collisions – Each DETPR port has a counter that is
incremented for each successive collision. If the counter reaches 64,
the port is segmented. The counter is reset on any transmission without
a collision.
No Loopback— This condition indicates the DETPR did not detect a
loopback (received data) of the transmitted data within a 256-bit time.
The cause could be a defective external transceiver or cable fault for port
0, or a defective transceiver for ports 1 through 8.
Link Integrity Fault (Logical)— This condition is the dropout of the
received data detect carrier from a port after the data has been sensed
on a given transmission to the port. The cause could be noise on the
line. This fault is only for one case—the loss of carrier not followed by a
collision.
The port is segmented after this condition occurs on two consecutive
transmissions. The logical link integrity failure can occur at any time in
the repeated packet. The port is restored when a collision is sensed on the
port that was segmented due to link failure. If a collision occurs on the
port before two failed link packets are sensed, the count is cleared. The
port is restored after the completion of four good transmissions.
Excessive-Length Collision— This indicates the port has seen the
collision-sense input active for greater than 200 µsec.

3
Configuration Rules
This chapter provides guidelines, rules, and constraints associated with
configuring and using the DETPR twisted-pair repeater.

DETPR Configuration Guidelines
Any configuration that uses DETPRs becomes a multisegment TwistedPair Ethernet. You cannot use more than two repeaters of any type
between any two nodes on an Ethernet/Twisted-Pair Ethernet. DETPRs
have eight (terminated) 8-pin MJ connectors to support up to eight
(radial) twisted-pair segments. DETPRs also have a ninth connector for
an optional connection to the one backbone segment of an Ethernet or
ThinWire Ethernet, using an Ethernet transceiver cable connected to an
H4005/H4000-BA or DESTA-B unit.
The concept of labeling only one segment of an Ethernet/Twisted-Pair
Ethernet as the backbone enforces the two-repeater rule. Multiple
backbone segments can interconnect using DEBET bridges.
NOTE
The DETPR is an active, twisted-pair Ethernet repeater. It is
not compatible with passive implementations of a twisted-pair
Ethernet.

Station Equipment Connection Guidelines
•

Maximum number of stations on a segment: 1

•

Maximum number of male/female junctions on a segment: 6
Each of the following equals one male/female junction:

–

Wallplate connection

–

DETPR port connection

–

Patch panel connection

Configuration Rules 9

DELNI/DETPR Guidelines
This section provides guidelines for Ethernet pyramids and standalone
pyramids.

Ethernet Pyramid
You can connect up to eight DETPRs to a backbone through a single
transceiver, using a DELNI interconnect unit. To do this, you need n+1
Ethernet transceiver cables, where n is the number of DETPRs. This
configuration is called a pyramid. You can have more than one such
DELNI/DETPR pyramid on a backbone, because each is treated as a
normal single load by the backbone.
DELNI/DETPR pyramids can only use the H4005/H4000-BA with the
heartbeat signal disabled, or a DESTA unit with the heartbeat/SQE test
disabled. You cannot arrange DELNI units in a pyramid to increase the
maximum number of DETPRs per transceiver to more than eight.
You can use maximum-length, 40-meter transceiver cables on either side
of the DELNI, but the thin/lossy office transceiver cable with its 4-to-1
length reduction is recommended for neatness. Also, Ethernet backbone
segments used by such pyramids are limited to 300 meters instead of the
usual 500 meters.

Standalone Pyramid
Just like single DETPRs, DELNI/DETPR pyramids can work in
standalone configurations without a backbone connection. In this case,
you must keep the DELNI in global mode, with an AUI loopback
connector (PN 12-222196-01) connected to the ninth connector normally
used for the backbone connection. In this configuration, the SQE test is
no longer present on the LOCAL DELNI ports. Therefore, the absence
of the test must be taken into account when using the DELNI for other
Ethernet controllers.

System Constraints and Guidelines
Twisted-pair cable is the physical medium that allows the DETPR to
achieve a low-cost connection to an Ethernet. The characteristics of
twisted-pair cable are drastically different from the characteristics of
Ethernet coaxial cable. However, the overall system constraints in terms
of timing and delay budgets remain the same. The DETPR has eight
twisted-pair ports with integral transceivers.

10 Configuration Rules

Twisted-pair cable segments consist of one link of up to 100 meters,
maximum. A link is a single length of twisted-pair cable with male 8-pin
MP connectors at each end. The delay for a twisted-pair cable segment
shall not exceed 1000 ns, and its loss shall not exceed 11.5 db.
You must use an Ethernet transceiver cable for any connection to an
Ethernet transceiver (H4000 or the first eight ports of DELNI). For
connections to an IEEE-802.3 transceiver (H4005 or DESTA), you must
use an IEEE-802.3 transceiver cable.

Twisted-Pair Wire Guidelines
Link length:

100 meters maximum with 24 AWG (typical)

Cable type:

Four twisted-pair 24 AWG or 22 AWG, DECconnect,
AT&T type C or D, or equivalent.
Maximum ac loss: 0.1 db/meter at 10 MHz
Maximum RDC: 0.094 ohms/meter (28.6 ohms/1000 feet)
Impedance: 100 ±15 ohms at 5 MHz and 10 MHz
Near-end crosstalk: 30 db maximum at 10 MHz

Number of nodes:

One node for each link

Termination:

100 ohms ±1% at both ends of the segment.

Twisted-Pair Ethernet Restrictions
To ensure the data integrity of the network, you should follow these
restrictions for the twisted-pair cable environment:
•

No unrepeated branches are allowed off a twisted-pair Ethernet
segment.

•

No telephone service should share the same cable sheath.

4
Troubleshooting
This chapter provides information on troubleshooting the DETPR. The
chapter covers the diagnostic tools available and how to use them to
isolate a problem.
Before beginning to troubleshoot the DETPR you should
1. Verify the installation of the unit.
2. Note the fault condition.
3. Isolate the problem. When isolating a problem, you have to look at
three basic components of the system:
— The DETPR.
— The wiring between the DETPR and the station equipment.
— The station equipment. This can be a workstation or a personal
computer (PC) using an IEEE 802.3 MAU, such as Digital’s H3350
transceiver or DE201 twisted-pair cable adapter.

12 Troubleshooting

Diagnostics
This section describes the DETPR unit’s internal power-up test and
external test.

Internal Power-Up Test
This test verifies the collision presence test (CPT) function on the twistedpair ports at the end of the internal self-test. At this time, the CPT is
disabled to all the twisted-pair ports. The CPT test sends data to all
the ports externally. Any collision sensed on a port verifies the collision
presence test.
Test features
•

Activated automatically upon initial power-up (plugging in the power
cord).

•

Runs for one complete cycle on the nine ports of the gate array.

•

Passes each port a packet containing 256 bits of preamble and 1792
bits of data (1s). The data is looped internal to the gate array in the
internal FIFO buffer, then compared.

•

Checks the collision counters and the segmentation of each port before
completion.

•

If an error is detected on a port, the port’s error indicator turns on.

External Self-Test
The sensing of collisions during the verification of a port is handled as
a retry. This is done until the port exceeds a collision count of 64, at
which time the port is segmented. If an error is sensed during data
comparison, the port is permanently segmented. This segmentation can
only be cleared by reperforming and passing the external self-test.

Troubleshooting 13

Test features
•

Activated by pressing the Test button.

•

Runs after collision presence test (CPT) is complete.

•

Loops a packet of 256 bits of preamble and 1792 bits of data (0s), and
compares the looped packet.

•

Tests each of the eight twisted-pair ports.

•

Tests the Ethernet port.

•

Checks for link integrity.

•

Checks for loopback capability of the transceiver chips.

How These Tests Differ
Internal

External

Gate array; a CPT/SQE test for each port;
preamble (all 1s)

A CPT/SQE test for each port;
preamble (all 0s)

Data path to the external interface
circuitry

Data path to the external interface
circuitry
Ability to receive and transmit
data

Standalone or Network Testing
Testing the DETPR in a standalone configuration isolates the unit from
potential external cabling problems or adverse network conditions.
Standalone testing allows you to verify that a problem is internal to
the device.

14 Troubleshooting

DETPR Control Panel Indicators
The indicators on the DETPR are used in troubleshooting a failing unit.
Figure 4–1 show the location of the various indicators on the DETPR.
Table 4–1 describes the function of each indicator.

Option Label

Ports 1-8 and
L in k Re ce ive Sta tu s L EDs

Port 0
Power LED
1

Segment
LED

Activity L ED

J10
Test Push Button
and LED
MA-0306-90A-CPG.DG
LJ-00089-TI0

Figure 4–1

DETPR Control Panel

Table 4–1 Control Panel Indicators
Indicator

When On . . .

Port 0 power LED

+12V is available at the port connector.

Port 0 segment LED

Port 0 is segmented.

Link receive status
LED, ports 1 to 8

The port is ready to receive or transmit data. When off,
the port is segmented. When blinking slowly (once a
second), the port was segmented and has been restored.
When blinking fast, there is port activity.

Test status LED

The external self-test is being run.

Activity LED

There is network activity.

Troubleshooting 15

Problem Solving
This section describes tests and procedures you can use when
troubleshooting the DETPR. The following tests can help you determine
the cause of a problem:
•

Power-up test

•

Self-test

•

Test with station equipment connected to the DETPR

•

Test with the Ethernet connected to the AUI port (port 0)

•

Crossover test

Each of the following test descriptions includes a table that shows how
to interpret test results. The tables also provide suggested solutions to
problem.

Power-Up Test
The power-up test runs automatically when ac power is applied to the
DETPR. After eight seconds, the results of the power-up test should
match those described in Installing and Using the DECrepeater 350.
If the results are different, use Table 4–2 as a guide to determine the
probable cause and the suggested solution.
Table 4–2 Power-Up Test Troubleshooting
If...

Then...

Do this...

The fan does not run
continuously.

The unit is faulty.

Replace the unit.

The power LED is
blinking.

The unit is faulty.

Replace the unit.

All LEDs are off.

There is a power
supply problem.

Check the power outlet and
cord to make sure the unit
is receiving ac power. If the
power LED is still off, replace
the unit.

The power LED
(+12 V) is off.

The transceiver or
cable might have a
short.

Disconnect the transceiver
cable and use the loopback
connector to verify. If the
power LED is still off, replace
the unit.

16 Troubleshooting

Self-Test
After the DETPR has powered up successfully, you can perform an
external test. After three seconds, the results of the self-test should
match those described in Installing and Using the DECrepeater 350.
If the results are different, use Table 4–3 as a guide to determine the
probable cause and the suggested solution.
Table 4–3 Self-Test Troubleshooting
If...

And...

Then...

Do this...

The port 0
segment LED
is off.

The loopback
connector is not
connected.

The port 0 segment
function is not
working.

Replace the
unit.

The port 1 to
-8 LEDs stay
on (green).

The lines are not
connected.

The twisted-pair port
is not working.

Perform the
crossover
test,
Table 4–6.

The power
LED is on
(green).

The loopback
connector is
connected, but the
loopback LED is out.

The loopback is
faulty.

Replace the
loopback
connector.

Troubleshooting 17

Test with Station Equipment Connected to DETPR
Installing and Using the DECrepeater 350 lists the correct LED pattern
that should appear 3 seconds after you push the Test button. If you
observe a different pattern, use Table 4–4 as a guide to determine the
probable cause and the suggested solution.
Table 4–4 DETPR-to-Station Equipment Test Troubleshooting
If...

Then...

Do this...

The port 0 segment
LED is on (amber).

The loopback
connector is faulty, or
port 0 is segmented.

Replace the loopback connector
or the unit.

The LED for a
connected port (1
to 8) or station is off.

The link, port, or
station is faulty.

Test the port with the
crossover test (Table 4–6),
check the link, and connect the
station to the operating port.

The LED for a
connected port (1
to 8) is off.

The port is
segmented because
of a station or
cabling problem.

Press the Test button to reset.
If the test does not reset
segmentation, then disconnect
the link to the faulty station.

The LED for a
connected port (1
to 8) is blinking
slowly.

The segmented port
is reset. ( Test LED
is green.)

No action is necessary.

The LED for an
unconnected port (1
to 8) is not blinking
(green) after the
self-test.

The port is faulty.

Replace the unit.

The Test LED is on
(amber).

The unit is running
the test.

Wait 30 seconds.

The Test LED does
not turn off after 30
seconds.

The Test LED or
unit is faulty.

Replace the unit.

The activity LED is
off.

There is no network
activity.

No action is necessary.

18 Troubleshooting

Test with Ethernet Connected
Installing and Using the DECrepeater 350 lists the correct LED pattern
that should appear 3 seconds after the test starts. If you observe a
different pattern, use Table 4–3 as a guide to determine the probable
cause and the suggested solution.
Table 4–5 Ethernet Test Troubleshooting
If...

Then...

Do this...

The port 0 segment
LED is on (amber).

The cable is not
connected.

Check the cable to make sure
it is connected properly.

The port 0 segment
LED is on, and
the port 0 cable is
properly installed.

The cable, the
transceiver, or the
network link is
faulty.

Replace the cable or
transceiver, then press the
Test button to reset. If the
test does not reset, correct the
network fault.

The LED for a
connected port (1
to 8) with station
activity is not
blinking.

The station
connection is faulty.

Replace the station connection
and perform the crossover test
(Table 4–6).

The activity LED is
not flickering.

There is no network
activity.

No action is necessary.

Troubleshooting 19

Crossover Test
If any two good ports are connected together, you should observe that the
green LEDs on both ports turn on. This indicates a successful link test in
both directions. This is true for DETPR-to-station and DETPR-to-DETPR
connections, and between ports on the same DETPR.
To check a suspected 1 to 8 twisted-pair port:
1. Connect one end of a twisted-pair crossover office cable to the
suspected port.
2. Connect the other end to a known good port. If you perform this
test between ports on the same DETPR, no network traffic should be
passed, so you must remove all active network connections. Do not
press the Test button during the connection.
The crossover test isolates a problem with any of the ports 1 to 8.
Table 4–6 shows the expected LED indications after three seconds.
Table 4–6 Crossover Test Troubleshooting
If Known
Good
Port is...

And
Suspected
Port is...

On (green)

Off

Receive
port is
inoperative
or segmented.

Disconnect the faulty port and
replace the unit at your earliest
convenience.

Off

On (green)

Transmit
port is
inoperative
or segmented.

Disconnect the faulty port and
replace the unit at your earliest
convenience.

Off

Transmit
and receive
ports are
inoperative
or segmented.

Disconnect the faulty port and
replace the unit at your earliest
convenience.

On (green)

Ports are both
operative.

No action is necessary.

Then the
Suspected...

Do this...

Reset segmentation by removing the office crossover cable and pressing the Test button.
If the Test button is pressed during the crossover test, and both ports are good, then both
LEDs turn off (segmentation condition).

20 Troubleshooting

Isolating Cable Faults
If a DETPR and H3350 MAU are connected by twisted-pair cabling,
observing their LEDs can help you isolate cable faults. Table 4–7
describes the meaning of different LED displays and the possible cable
fault indicated.
Table 4–7 DETPR and H3350 Twisted-Pair Cable Fault Isolation
If...

And...

Then...

Check for a...

The H3350’s
LI LED is
off, and its X
LED is on or
blinking.

The
DETPR’s
port LED
is on.

The H3350 is not receiving
link pulses. The H3350 may
try to transmit, but cannot
because it is not receiving
link pulses from the DETPR
port. The DETPR port LED
does not blink when the X
LED blinks.

Short or open
in the DETPR’s
transmit pair.

Note: The X LED on the
H3350 may blink, indicating
that the H3350 is trying to
receive data from its AUI
port. However, data is not
transmitted because of the
lack of link pulses.
The H3350’s
LI and CP
LEDs are
blinking when
its X LED is
blinking

The
DETPR’s
port LED
is off or
blinking.

The H3350’s
LI LED is on
or blinking,
and its X
LED is on.

The
DETPR
port’s LED
is off.

A collision is occurring
whenever the H3350 tries
to transmit. When this
happens, the X, LI, and CP
LEDs blink together.

Short between
the transmit
pair and the
receive pair.

Note: If there is DETPR
activity present, the
DETPR’s port LED should
be off, indicating port
segmentation. (See the
following.)
A collision is occurring each
time the DETPR port tries
to transmit. The DETPR
port is segmented and
continues to transmit link
pulses and data.

Short between
the transmit
pair and the
receive pair.

Troubleshooting 21

Table 4–7 (Cont.) DETPR and H3350 Twisted-Pair Cable Fault Isolation
If...

And...

Then...

Check for a...

The H3350’s
LI LED is
on, and its X
LED is on or
blinking

The
DETPR’s
port LED
is off.

The H3350 is trying to
transmit. The DETPR port
is segmented because it is
not receiving link pulses
or data from the H3350.
The LI LED will not blink
because the DETPR port
cannot transmit, due to the
lack of link pulses.

Short or open
in the DETPR’s
receive pair.

The H3350’s
LI LED is
on, and its X
LED is on.

The
DETPR
port’s LED
is off.

The DETPR port is trying
to transmit, but cannot
because it is not receiving
link pulses or data from
the H3350. The DETPR
port segments on DETPR
activity.

Short or open
in the DETPR’s
receive pair.

Note: The H3350’s LI LED
does not blink with DETPR
activity.

A
DETPR Specifications
This appendix list the physical, electrical, and environmental
specifications for the DETPR unit. The appendix also provides part
numbers, cable requirements, and connector pinouts.

Physical Specifications
Part

Height

Width

Depth

DETPR-AA
/BA

4.63 inches
(11.76 cm)

19.25 inches
(48.9 cm)

12.00 inches
(30.48 cm)

DETPR-AA
/BB

3.44 inches
(8.74 cm)

17.0 inches
(43.18 cm)

11.75 inches (29.85 cm)

Electrical Specifications
The DETPR input voltage is factory set, and is not field selectable.

AC Power Requirements
Requirement

DETPR-AA/BA

DETPR-AB/BB

Factory-set normal
voltage

110 V to 120 V, 3-wire,
single phase

220 V to 240 V, single
phase

Frequency

47 Hz to 63 Hz

Running current
(maximum)

0.725 amps

0.360 amps

Power (maximum)

80 watts

Overload protection

Fuse (not field replaceable)
3 AG, 2.0 amps, 250 V

Fuse (not field
replaceable) 3 AG,
2.0 amps, 250 V

DETPR Specifications 23

NOTE
AC power is provided to the unit through a single standard (3prong) IEC connector. AC power is not switched, to prevent the
accidental loss of power to the unit. When powered down, the
unit exhibits no load to any of the ports. The fuse is mounted on
the power supply module and is not field replaceable.

DC Power Requirements
Voltages
+5.1 V, +12.0 V, and +10.0 V

Environmental Requirements
Temperature
Rapid temperature changes may affect operation. Therefore, do not
operate the DETPR near heating or cooling devices, large windows, or
doors that open to the outside.
•

Operating: 5° to 50°C (41° to 122°F)
The DETPR must be within operating temperature range before
power-up.

•

Nonoperating: -40° to 66°C (-40° to 151°F)

•

Maximum temperature change per hour: 20°C (36°F)

Altitude
If you are operating the DETPR above 2.4 km, decrease the operating
temperature by 1.8°C/1000 m (1°F/1000 ft).
•

Operating: 2.4 km (8000 ft)

•

Nonoperating: 9.1 km (30,000 ft)

Relative Humidity
•

Operating: 10% to 90% (noncondensing)
40% to 60% is normally recommended.

•

Nonoperating: 10% to 90% (noncondensing)

24 DETPR Specifications

Part Numbers
Part

Part Number

Transceiver port Ethernet loopback connector

12-22196-01

Rackmount kit (for -BA, -BB versions only)

H041-AA

Power cord
United States

17-00083-09

Ireland, United Kingdom

BN02A-2E

Austria, Belgium, Czechoslovakia, Finland, France,
Germany

BN03A-2E

Switzerland

BN04A-2E

Australia, New Zealand

BN05A-2E

Denmark

BN06A-2E

Italy

BN07A-2E

Cable Requirements
For configuration planning information, see the DECconnect System
Planning and Configuration Guide. The configuration guidelines for
the DECrepeater 350 are the same as for the DEMPR unit, except
cable lengths are different and daisy-chaining is not permitted with
the DECrepeater 350.

Cable Type

Digital Part
Number

Length Restrictions

Transceiver cable

BNE3H
BNE4C

50 meters (164 feet) maximum
if going directly to a
transceiver, or up to 45 meters
(148 feet) total maximum if
connected to a DELNI unit.

Twisted-pair cable

H8245A
(non-Plenum
rated)
H8246A
(Plenum
rated)

Maximum of 90 meters/port.

DETPR Specifications 25

Digital Part
Number

Cable Type

Length Restrictions

Twisted-pair office crossover
cable, 8MP 8MP, 4 cond,
2 UTP office cable with
crossover 10BaseT

BN24F

Available in lengths of 3, 4,
and 7 meters

SER cable, 8MP 8MP, 8
cond, 4 UTP patch cable pin
to pin

BN24G

Available in lengths of 1, 3, 4,
and 7 meters

Unshielded Twisted-Pair Cable Requirements
Requirement

Description

Wire specification

22 to 24 gauge wire, solid copper

Cable supported

DECconnect twisted-pair data cable (H8245A or
H8246A), AT&T Type C or D, IBM Type 3, or Northern
Telecom 4 Pair unshielded twisted pair

Cable length

90 m (296 ft) typical maximum, from wiring closet or
satellite equipment room (SER) to office

DC resistance
per conductor
(maximum)

0.094

Impedance at 5 MHz
and 10 MHz

100

/m (28.6

/1000 ft)

Unshielded Twisted-Pair Cable Environmental Constraints
Constraint

Description

Signals

No other signals should be used in the same cable
sheath. For example, voice and data signals cannot be
run within the same sheath.

Noise

Unshielded twisted-pair cable must remain at least
30.48 cm (1 ft) from any type of high-voltage power
device or electrical noise source.

26 DETPR Specifications

Connector Pinouts
The DETPR has an 8-pin MJ connector for its twisted-pair ports (1 to 8)
and a 15-pin D connector for its AUI port (0).

8-Pin MJ Connector (Ports 1 to 8)
Pin

Signal Name

Transmit +

Transmit –

Receive +

NC (no connection)

Receive –

15-Pin D Connector (Port 0)
Pin

Signal Name

NC (no connection)

Collision presence +

Transmit +

Logic ground

Receive +

Power return

Ground (not used)

Logic ground

Collision presence –

Transmit –

Logic ground

Terminated to ground by a 0.1 µfd capacitor and balanced by a 39.2 ohm resistor.

DETPR Specifications 27

Signal Name

Receive –

+12 Vdc power

Logic ground

Ground (not used)

Connector
(metal shell)

Chassis ground

Terminated to ground by a 0.1 µfd capacitor and balanced by a 39.2 ohm resistor.