Allied Telesis CentreCOM AT-270T User manual

PN 613-10436-00 Rev. A 960209
Copyright 1996 Allied Telesyn International, Corp.
CentreCOM is a trademark of Allied Telesyn International, Corp.
All rights reserved. No part of this publication may be reproduced without prior
written permission from Allied Telesyn International, Corp.
Allied Telesyn International, Corp. reserves the right to make changes in
specifications and other information contained in this document without prior
written notice. The information provided herein is subject to change without
notice. In no event shall Allied Telesyn International, Corp. be liable for any
incidental, special, indirect, or consequential damages whatsoever, including but
notlimitedtolostprofits,arisingoutoforrelatedtothismanualortheinformation
contained herein, even if Allied Telesyn International, Corp. has been advised of,
known, or should have known, the possibility of such damages.
ATI
950 Kifer Road
Sunnyvale, CA 94086 USA
Tel [phone] • Fax [phone]
Technical Support Tel [phone] • Fax [phone]
International Fax [phone]
AT-270T and AT-440T
CentreCOM™
Multiport 10BASE-T Transceive
rs
User Manual

Introduction
The CentreCOM Multiport Transceivers are two and four port twisted pair
transceivers for users of Ethernet Local Area Networks (LANs). These
transceivers provide the electronic and physical interface between the Ethernet
10BASE-T cabling and the IEEE 802.3/Ethernet station Data Terminal
Equipment (DTE).
The AT-270T transceiver’s circuit design supports two Attachment Unit
Interfaces (AUIs) with a single circuit board and twisted pair interface. The AT-
440T transceiver incorporates the same circuit design but supports four AUIs to
the LAN media. CentreCOM Multiport Transceivers are compact and offer
superior quality and performance. They are easily and rapidly installed, and their
compact design supports installations along narrow raceways.
Preparation
SQE/Heartbeat Test
TheAT-270T/AT-440ThaveSQE/HeartbeatTestenable/disableswitchlocatedon
the top of the chassis beneath a round access hole. The SQE Test switch will
providetheIEEE 802.3 Ethernet SQETestfunctionenableordisable.If the DTE
to which the multiport transceiver is connected requires the SQE/Heartbeat Test
function, then place the SQE Test switch into the ON position.
If the DTE to which the multiport transceiver is connected does not require the
SQE/Heartbeat Test function, or if the DTE is a repeater, then disable the
Heartbeat function by placing the switch to OFF. Heartbeat and repeaters many
times do not want the Heartbeat function and, in fact, may cause excessive
Collisions if Heartbeat is enabled. It is recommended that the Heartbeat function
is disabled whenever an MAU is connected to a repeater unit.
Installation
1. The AT-270T/AT-440T has been designed to install between the UTP RJ45
connection and up to two DTE or workstation AUI connectors.
2. Power on the DTE and check that the Power LED on the transceiver is
illuminated.
3. Check the SQE Test LED to verify the correct setting for your equipment.
4. Plug the UTP cable into the RJ45 receptacle located on the transceiver.
5. Ensure the equipment on the opposite end of the UTP link is operational. If
so, the Link LED should illuminate.
6. If the Polarity LED is illuminated, no action should be necessary. This
indicatates that the AT-270T/AT-440T swapped the RD+ and RD- signals
andhascorrected the polarityreversal.Thisfunctionshould not be confused
with the UTP wiring cross-over which is hard wired into the UTP cable.
7. If you have a good Link LED on both the local and remote tranceivers, your
stations will now communicate.
Status Indicators
ThetwistedpairCentreCOMMultiportTransceiversfeaturessevenLEDs.These
indicators are as follows:
Power—Illuminates when power is received from the DTE or workstation.
Link—Illuminates when a good link on the RD pair has been established.
Transmit—Indicates packets are transmitted onto the UTP media.
Receive — Indicates packets are received from the UTP media.
Polarity—ThisLEDwillextinguishiftheautopolaritycorrectionhastakenplace.
This+-signalreversaltakesplaceontheRD-andRD+signallinesonly.ThisLED
is normally ON.
SQE Test—Heartbeat status LED is ON if Heartbeat is enabled and OFF if
Heartbeat is disabled.
Collision—Indicates a Collision has occurred.
Twisted Pair Cable
Thereareseveraltypesoftwistedpaircables.TheIEEE802.3specificationstates
that the maximum length of a 10BASE-T link segment is 100 meters (328 ft.) of
UTP wiring. For network reliability, these limits should not be exceeded.
Remember, if another AT-270T MAU is connected to the opposite end of the link,
theUTP cabling mustbecrossed. i.e., RD-andRD+signals must beswappedwith
the TD- and TD+ signals respectively. The UTP cable should be 26 to 22 AWG (0.4
to0.6mm)wireinamulti-wirecablewith 100 Ω impedance.TheUTPlinksegment
should have the TD pair and the RD pair crossed as shown below.
Table 1: RJ45 Connector Pin-Out
Pin No. Signal Name
Pin No. Signal Name
1 TD+ 5 Not Used
2 TD- 6 RD-
3 RD+ 7 Not Used
4 Not Used 8 Not Used
Table 2: AUI Pin-Out
Pin No. Signal Name Pin No. Signal Name
1 LOGIC GND 9 COL-
2 COL + 10 TX-
3 TX- 11 LOGIC GND
4 LOGIC GND 12 RX-
5 RX+ 13 POWER +12 Vdc
6 POWER RETURN 14 LOGIC GND
7 N/C 15 N/C
8 LOGIC GND

Introduction
The CentreCOM Multiport Transceivers are two and four port twisted pair
transceivers for users of Ethernet Local Area Networks (LANs). These
transceivers provide the electronic and physical interface between the Ethernet
10BASE-T cabling and the IEEE 802.3/Ethernet station Data Terminal
Equipment (DTE).
The AT-270T transceiver’s circuit design supports two Attachment Unit
Interfaces (AUIs) with a single circuit board and twisted pair interface. The AT-
440T transceiver incorporates the same circuit design but supports four AUIs to
the LAN media. CentreCOM Multiport Transceivers are compact and offer
superior quality and performance. They are easily and rapidly installed, and their
compact design supports installations along narrow raceways.
Preparation
SQE/Heartbeat Test
TheAT-270T/AT-440ThaveSQE/HeartbeatTestenable/disableswitchlocatedon
the top of the chassis beneath a round access hole. The SQE Test switch will
providetheIEEE 802.3 Ethernet SQETestfunctionenableordisable.If the DTE
to which the multiport transceiver is connected requires the SQE/Heartbeat Test
function, then place the SQE Test switch into the ON position.
If the DTE to which the multiport transceiver is connected does not require the
SQE/Heartbeat Test function, or if the DTE is a repeater, then disable the
Heartbeat function by placing the switch to OFF. Heartbeat and repeaters many
times do not want the Heartbeat function and, in fact, may cause excessive
Collisions if Heartbeat is enabled. It is recommended that the Heartbeat function
is disabled whenever an MAU is connected to a repeater unit.
Installation
1. The AT-270T/AT-440T has been designed to install between the UTP RJ45
connection and up to two DTE or workstation AUI connectors.
2. Power on the DTE and check that the Power LED on the transceiver is
illuminated.
3. Check the SQE Test LED to verify the correct setting for your equipment.
4. Plug the UTP cable into the RJ45 receptacle located on the transceiver.
5. Ensure the equipment on the opposite end of the UTP link is operational. If
so, the Link LED should illuminate.
6. If the Polarity LED is illuminated, no action should be necessary. This
indicatates that the AT-270T/AT-440T swapped the RD+ and RD- signals
andhascorrected the polarityreversal.Thisfunctionshould not be confused
with the UTP wiring cross-over which is hard wired into the UTP cable.
7. If you have a good Link LED on both the local and remote tranceivers, your
stations will now communicate.
Status Indicators
ThetwistedpairCentreCOMMultiportTransceiversfeaturessevenLEDs.These
indicators are as follows:
Power—Illuminates when power is received from the DTE or workstation.
Link—Illuminates when a good link on the RD pair has been established.
Transmit—Indicates packets are transmitted onto the UTP media.
Receive — Indicates packets are received from the UTP media.
Polarity—ThisLEDwillextinguishiftheautopolaritycorrectionhastakenplace.
This+-signalreversaltakesplaceontheRD-andRD+signallinesonly.ThisLED
is normally ON.
SQE Test—Heartbeat status LED is ON if Heartbeat is enabled and OFF if
Heartbeat is disabled.
Collision—Indicates a Collision has occurred.
Twisted Pair Cable
Thereareseveraltypesoftwistedpaircables.TheIEEE802.3specificationstates
that the maximum length of a 10BASE-T link segment is 100 meters (328 ft.) of
UTP wiring. For network reliability, these limits should not be exceeded.
Remember, if another AT-270T MAU is connected to the opposite end of the link,
theUTP cabling mustbecrossed. i.e., RD-andRD+signals must beswappedwith
the TD- and TD+ signals respectively. The UTP cable should be 26 to 22 AWG (0.4
to0.6mm)wireinamulti-wirecablewith 100 Ω impedance.TheUTPlinksegment
should have the TD pair and the RD pair crossed as shown below.
Table 1: RJ45 Connector Pin-Out
Pin No. Signal Name
Pin No. Signal Name
1 TD+ 5 Not Used
2 TD- 6 RD-
3 RD+ 7 Not Used
4 Not Used 8 Not Used
Table 2: AUI Pin-Out
Pin No. Signal Name Pin No. Signal Name
1 LOGIC GND 9 COL-
2 COL + 10 TX-
3 TX- 11 LOGIC GND
4 LOGIC GND 12 RX-
5 RX+ 13 POWER +12 Vdc
6 POWER RETURN 14 LOGIC GND
7 N/C 15 N/C
8 LOGIC GND

PN 613-10436-00 Rev. A 960209
Copyright 1996 Allied Telesyn International, Corp.
CentreCOM is a trademark of Allied Telesyn International, Corp.
All rights reserved. No part of this publication may be reproduced without prior
written permission from Allied Telesyn International, Corp.
Allied Telesyn International, Corp. reserves the right to make changes in
specifications and other information contained in this document without prior
written notice. The information provided herein is subject to change without
notice. In no event shall Allied Telesyn International, Corp. be liable for any
incidental, special, indirect, or consequential damages whatsoever, including but
notlimitedtolostprofits,arisingoutoforrelatedtothismanualortheinformation
contained herein, even if Allied Telesyn International, Corp. has been advised of,
known, or should have known, the possibility of such damages.
ATI
950 Kifer Road
Sunnyvale, CA 94086 USA
Tel [phone] • Fax [phone]
Technical Support Tel [phone] • Fax [phone]
International Fax [phone]
AT-270T and AT-440T
CentreCOM™
Multiport 10BASE-T Transceive
rs
User Manual