@autro1.UUCP ("teig_y", yvind Teig) (05/03/91)
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Transputer link via optic cable.
We are thinking about using optic links between transputer embedded-
controller boxes. I know about the Inmos application note "Connecting
INMOS links". I also know about a board from TTT "Transputer Technologie
Transfer" that has Tx-links to optic, with all control lines encoded
into fibeglass optic.
Does anyone out there have any experience?
Q1: What kind of optical TX / RX do you use?
(HFBR 1402 / 2402) ?
Q2: What kind of cable?
(Fiber, plastic, attenuation?)
Q3: We plan to use 5 Mbit/sec, over 100m max. Do you
have any figures for Bit Error Rate (BER). I suppose
that it must be quite good (10 EXP-14 or better) to use
bare transputer links.
Q4: Does anyone have any suggestion as to which method to use
to multiplex reset, analyse and notError on the optic cable?
Q5: We need a duplex cable, quite rugged, for use inside ships.
It needs to withstand some oil dust, but not salt water.
Any reference to a good cable? (No electrical lines needed).
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Oyvind Teig, AUTRONICA
7004 Trondheim, Norway
tel: + 47 7 581268
fax: + 47 7 919320
email: nuug!autro1.teig
03.05.91
---------------------------------------------------------------------jpp@specialix.co.uk (John Pettitt) (05/08/91)
@autro1.UUCP ("teig_y", yvind Teig) writes: >--------------------------------------------------------------------- >Transputer link via optic cable. >We are thinking about using optic links between transputer embedded- >controller boxes. I know about the Inmos application note "Connecting >INMOS links". I also know about a board from TTT "Transputer Technologie >Transfer" that has Tx-links to optic, with all control lines encoded >into fibeglass optic. >Does anyone out there have any experience? We have been running T222's on the end of up to 1Km of glass fibre. We have an effective bandwidth at that distance of 1mbit (we run at 10 mbit but the speed of light delays the data by 6 micro seconds at a km). We took the notes in the application note and the HP apps notes on fibre and away we went. We are using 62.5 glass (plastic is not up to much more than 30M). We are seeing error rates close to 0 - I.E. better than the 1 in 10^14 that we were expecting. As it happens we do run a checksummed transport protocol over a conectionles network layer to provide robustness - but then we are in a hostile environment (office use ! :-). [ the product is a distributed, fault tolerant I/O system for UNIX systems - up to 128 ports at 38K baud with 17 T222's spread over up to 4 Km of cable. Topology is free form and will tolerate loss of links between units by routing over alternate links ] We don't send the control signals down the line - as the remote is expected to work. If it does not poke a watchdog every 250ms it gets reset by a one shot in the hardware design. This removes the need for reset in our application. Multiplexing two control signals is possible with varying degrees of dificulty depending on the delay in propagation you will tolerate. If delay is not a factor then you can use a subcarrier on the fiber to carry the control signals. Hope this helps - if you want more info please mail me. -- John Pettitt, Specialix International, Email: jpp@specialix.com Tel +44 (0) 9323 54254 Fax +44 (0) 9323 52781 Disclaimer: Me, say that ? Never, it's a forged posting !