Re: LM35 - Length of cable ?

["Dave McLaughlin" <dave@xxxxxxx>]

Hi Frank,

Multi master is the greatest thing I like about it. Works very similar
to
the way Ethernet talks on the bus as regards detecting collisions,
priority
etc.

Go to www.kvaser.se and have a look at the documentation section as there
is
loads to read.

The Microchip MCP2510 is what I currently use and is easy to interface
being
SPI. You only need 2 chips (plus the CPU of course) and you then have a
CAN
bus interface. There are microcontrollers with built in CAN and
Microchip
and others do them but the costs of the dev kits put me off using them.
I
use the Atmel AVR with the MCP2510 and I can then design whatever I need
as
I already have the code to talk to them.

The nice thing about CAN that I like, is that you can get the device to
transmit anytime without being requested to, as when using a
Master-Slave
setup with RS485. The message with the highest priority gets the bus and
the
other has to wait (meaured in uS in some cases) till the current device
completes transmission.

Even the lowly Skoda Octavia uses CAN bus these days.

Once you have played with CAN it opens up some serious control
possibilities. I am currently wiring up my garage with CAN to detect
and
control my central heating boiler and the open/closed state of the
garage
door. All on the same twisted pair. I have other ideas to add and the
beauty
of CAN is the ability to add devices without having to change any code
on
the existing devices, other than the one that is going to receive the
new
data.

A bit long winded but you should checkout the link above as it has some
very
interesting reading.

Regards
Dave...

----- Original Message -----
From: "Frank Mc Alinden" <armagh@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Friday, May 31, 2002 1:01 PM
Subject: Re: [ukha_d] LM35 - Length of cable ?


> Hi Dave
>            
Whats the difference between rs485 comms and the Can bus ? is
it
> the protocol . I see Microchip have can bus chips. Are they easy to
use?
> Some of the industrial (Allen Bradley) plc suppliers use the can
bus
system.
> What are the advantages?
>
> Frank Mc
> ----- Original Message -----
> From: "Dave McLaughlin" <dave@xxxxxxx>
> To: <ukha_d@xxxxxxx>
> Sent: Friday, May 31, 2002 9:55 PM
> Subject: Re: [ukha_d] LM35 - Length of cable ?
>
>
> > Mark,
> >
> > My weather station has about 20ft or so of 4 core unscreened and
it
works
> > fine. There is a small amount of noise but by averaging samples I
get a
> > better readout. Only changes by about 0.1 of a degree and
considering
the
> > accuracy of the LM35 this is acceptable anyway.
> >
> > Once I get my act together I will have a CAN bus based sensor
interface
> that
> > should alleviate this problem and allow you to make runs as long
as 500m
> > without problems of noise. I already have designs that can read
digital
> data
> > but not yet with the analog.
> >
> > Dave...
> >
> > ----- Original Message -----
> > From: "Frank Mc Alinden" <armagh@xxxxxxx>
> > To: <ukha_d@xxxxxxx>
> > Sent: Friday, May 31, 2002 12:30 PM
> > Subject: Re: [ukha_d] LM35 - Length of cable ?
> >
> >
> > > Mark
> > >         If its only
20 ft  the 4 core security cable would work . I
dont
> > > imagine you would be that unlucky .
> > >
> > > Frank Mc
> > > ----- Original Message -----
> > > From: "Mark Marooth" <MMarooth@xxxxxxx>
> > > To: <ukha_d@xxxxxxx>
> > > Sent: Friday, May 31, 2002 9:19 PM
> > > Subject: Re: [ukha_d] LM35 - Length of cable ?
> > >
> > >
> > > >
> > > >
> > > > Hi Frank,
> > > >
> > > > Runs should be no longer than 20 feet through the roof
space.
You've
> > also
> > > > confirmed what I suspected about noise, as I am running
thorugh roof
> > > space,
> > > > think I'll use something shielded.
> > > >
> > > >
> > > > Mark
> >
> >
> >
> >
> > For more information: http://www.automatedhome.co.uk
> > Post message: ukha_d@xxxxxxx
> > Subscribe:  ukha_d-subscribe@xxxxxxx
> > Unsubscribe:  ukha_d-unsubscribe@xxxxxxx
> > List owner:  ukha_d-owner@xxxxxxx
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
>
>
>
> For more information: http://www.automatedhome.co.uk
> Post message: ukha_d@xxxxxxx
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>
>



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