CentreCOMMini Hubs

• IEEE 802.3 com-pliant 10BASE-T andEthernet Version 1.0and 2.0 compatible

• UTP uplink for network cascading

• Packet regenera-tion, automatic polarity detection/correction and link test capabili-ties

• Segment parti-tioning and jabber lock-up protection

• Port and SystemStatus LEDs

• Wall and desktop mounting simplified

• Rugged steelchassis

• Lifetime warran-ty*(See reverse side for details)

These mini hubs are twisted pair hubsintended to connect as many as eight IEEE802.3 10BASE-T network segments throughone unit. Each hub has one twisted pair portspecifically designed with an uplink (cascad-ing) capability supporting a Media DependentInterface (MDI/MDI-X) crossover switch. Asmany as four hubs can be cascaded togetherto form an independent workgroup.

These mini hubs utilize the latest IC andSurface Mount Technology (SMT), whichincreases functionality and reliability. Addi-tionally, these hubs are very small in size yetthey provide the complete functionality oflarge hubs including packet regeneration andnetwork partitioning. The packet regenerationresults in a higher performance network byregenerating preamble, retiming the datapackets and extending collision fragments toensure collision enforcement by all nodes.Each segment automatically detects the polarityof the receive pair and reverses should thepair be incorrectly installed. The IEEE definedlink integrity test function continually moni-tors the receive pair to ensure link continuity.It also includes a partitioning capability whereeach segment automatically disconnects itselfafter repeated collisions are detected.

These mini hubs support jabber lock-upprotection on all interfaces, preventing trans-ceiver lock-up resulting from packets thatexceed the maximum packet length.

Network diagnostic LEDs are provided onthe front of the mini hubs to aid in monitoringsystem and network performance. There isone LED associated with each twisted pairsegment that indicates “Link OK” (indicatingan operational segment). Additionally, thereare three central LEDs indicating “Activity,”“Collision” and “Power.”

Installation of these mini hubs is simpleand straightforward. For desktop use, self-adhesive rubber feet are provided. For wallmount, two methods can be utilized. The bot-tom of each chassis contains two “keyhole”openings for hanging on wall protrusions (e.g.screws). Alternatively, self adhesive velcro strips are provided for easy attachment.

Multiport Twisted Pair Mini Hubswith External Power AdaptersAT-MR415T 4-Port Mini HubAT-MR815T 8-Port Mini Hub

S P E C I F I C A T I O N S

STATUS INDICATORSLink OK Indicates there is a valid link between segments

Front Panel Central:Power Indicates power is onCollision Indicates there is a collision detected within the hubActivity Indicates the hub is transmitting packets out to all ports

PACKET TRANSMISSION CHARACTERISTICSDelay Times:

(Any segment in to all other segments out)UTP to UTP

Start of Packet 700 ns MaximumCollision to Jam 700 ns Maximum

Preamble:Input Minimum of 32 bits including SFDOutput 64 bits including SFD (last 2 bits are 1,1)

Jam Output:A pattern of 1,0 is sent to all segments when a transmit collision is detected.This pattern is also sent to all segments (except receive port) when a receive collision isdetected.

Packet Fragment Extension:96 bits including preamble. Packet fragments are extended using the (1,0) datapattern.

Auto Partition/Reconnection:Each segment will partition itself from the other segments if either 32 consecu-tive collisions occur or if the collision detector of a segment is onfor longer than 1 ms. Reconnection occurs after data is transmitted or receivedwithout collision on the partitioned port for 512 bit times (IEEE standard algorithm) or after data trans-mitted without collision for 512 bit times (alternate algorithm).

Jabber Lock-Up Protection:Packet output is momentarily interrupted for 96 bit times when packet transmis-sion exceeds 64K bits.

UTP INTERFACE (IEEE 802.3 10BASE-TCOMPLIANT)

Transmitter: Typical WorstPeak Differential

Signal Amplitude 2.5 V 2.2 to 2.8 VTransmitter Jitter ± 3.5 nsHarmonics Content < 27 dB below

fundamentalCommon Mode

Output Voltage 50 mVSilence Voltage 0 ± 50 mVLink Test Pulse 100 ns 60 to 130 nsOutput Impedance 100 85 to 115 UTP Length 100 meters

Receiver:Receiver Threshold -400 mV -300 to -520 mVDifferential Noise Rejection 300 mV

Ports: MR815T MR415TTwisted Pair (RJ45 connector) 8 4

POWER CHARACTERISTICSExternal Power Adapter:

Voltage 100 to 120 VAC200 to 240 VAC, Continental Europe200 to 240 VAC, UK50/60 Hz

Current 0.5 A/0.25 A

Power: 12 watts (worst)

*One year warranty on power supply.

PHYSICAL CHARACTERISTICSDimensions MR415T 11.2 cm x 9.8 cm x 2.6 cm

(4.4 in. x 3.9 in. x 1.0 in.)MR815T 17.5 cm x 9.8 cm x 2.6 cm

(6.9 in. x 3.9 in. x 1.0 in.)Weight MR415T 284 grams (10 oz.)

MR815T 426 grams (15 oz.)Temperature

Operating 0° to 40° CStorage -20° to 70° C

Relative Humidity 5% to 80% non-condensing

Electrical/Mechanical Approvals:EMI FCC Class ASafety UL, CSA, TUV-GS

617-00141-05 A-25T9608

© 1995 Allied Telesyn International Corp. Information in this document is subject to change without notice. Individual product warranties are as represented in documentation included with each modelwhen delivered. The reader may obtain specific warranty information by contacting a local Allied Telesyn office or reseller. CentreCOM and CardAssistant are trademarks of Allied Telesyn InternationalCorp. Ethernet is a registered trademark of Xerox Corporation.

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