Re: LM35 - Length of cable ?

["Frank Mc Alinden" <armagh@xxxxxxx>]

Thanks Dave
                   
I have downloaded and read up a while back on the pic
chip you refer to and the can bus protocol .It was using the Allen
Bradley
stuff at work that drew my attention to it . I dabble with the pic,s
and
thought about using the can system but thought it was out of my depth.
Im
going to have to have another look at it. How do you set message
priority
level ? Is it hard to get up and running. Im only a novice when it comes
to
comms.
Frank Mc
----- Original Message -----
From: "Dave McLaughlin" <dave@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Friday, May 31, 2002 10:10 PM
Subject: Re: [ukha_d] LM35 - Length of cable ?


> 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
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> > >
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> > >
> >
> >
> >
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>
>
>
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