Date   : Sat, 01 Sep 2007 11:02:28 +0100
From   : bbcmailinglist@... (Ian Wolstenholme)
Subject: Econet oddities

I would strongly recommend throughly testing the wiring
at all points along the network for continuity.  It's very 
easy to get a cross wire or a bad connection or bad soldering
which can cause problems which do not have an immediately
obvious source (such as intermittent Not listening or Line jammed
errors).

If you can get your hands on a FLAT box this is a very good tool
for testing Econet wiring:

http://www.beebmaster.co.uk/econet/flatbox.html

There are also instructions on how to test the wiring of a network
in the Econet Installation Guide 1984 & 1988 available@...

When I pulled all my Econet wiring to bits in March 2005 with the
object of eliminating the illegal branch line I had created and adding
an A4000 to the network, I had so many problems with the new
wiring that I gave up in the end.  It's still all sitting in a box and
the network is being held together with DIN leads and T-pieces.

More recently I had a go with the FLAT box to test some of the
wiring I had done and there were lots of bad connections along
the way.  I also found that some of the Econet DIN leads (including
some moulded ones I bought) were made incorrectly and were
not wired straight through pin-for-pin, so Clock + was being
connected at one end to Data + at the other end for instance.  I had
about 3 or 4 leads like this as I remember so that would be something
to check.

I've never had much trouble with one of the Level 1 clocks but
they do not operate as fast as the Level 3 or SJ Research one
because the Mark and Space are always the same length.  The
Acorn default clock speed setting, mentioned in several books,
is 200KHz although the Level 1 clock doesn't have this setting!
I would try it at 153K or 115K until you get things working 
reliably and then increase it to 230K.

It would also be worth checking that all the stations on the
network have different station numbers and that none of them
is set to station 0 or station 255.  If you have any older BBC Bs
with Issue 3 or 2 boards then check that they haven't got the
clock generation or termination components fitted to the Econet
interface.

Finally, it's a good idea to check that all stations can communicate
with each other.  You don't need a file server running to do this,
you can use the Notify OSWORD call to send messages between
stations:

http://www.beebmaster.co.uk/downloads/notify.txt

Try doing this with different combinations of stations switched on
or off and plugged in or unplugged from the network, this will
help to isolate faults associated with individual stations.

Econet is one of the best things in the world when it's running
smoothly - but it's one of the most soul-destroying, frustrating
things when it doesn't work!!

Best wishes,



Ian



----- Original Message -----
From: Chris Priest [mailto:chris.priest@...]
To: bbc-micro@...
Sent: Wed, 29 Aug 2007 14:28:40 +0100
Subject: Re: [BBC-Micro] Econet oddities

Chris Priest wrote:
> Rob wrote:
>> It sounds like you've done your best, but it is almost certainly the
>> wrong cable; econet uses a differential signal like ethernet 10baseT
>> rather than a signal-to-ground like RS232/432 seral.  For this to work
>> reliably at speed, the cables in the pair are supposed to be twisted
>> together, and always kept the same length.
>>
>> Also, whats in the cables from your sockets to the Beebs?
>>
>>   
>
> Cable from Socket to Beeb is the same stuff as used for the socket 
> boxes. 4 core + screen.
>
>>  
>>> The cable is shielded, the shield being used as earth.
>>>     
>>
>> Make sure you only connect shields at *one* end to avoid creating hum
>> loops ...
>>
>>   
>
> I was under the impression that you had to connect the shield at all 
> boxes, apart from you didn't need to connect to each of the earths 
> inside the box?
>
>> I think mine is a homemade one (not by me) using a 555 ... I really
>> need to trace it out sometime & post a schematic..
>>
>>   
> Would be interested to see it if you get time to map it out.
>
> Cheers
> Chris
>
>> Rob
>>
>> _______________________________________________
>> bbc-micro mailing list
>> bbc-micro@...
>> http://lists.cloud9.co.uk/mailman/listinfo/bbc-micro
>>   
>
>


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