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'[PIC] DS1820 wire how long can it go ?'
2007\08\02@054942 by cllow2020

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part 1 347 bytes content-type:text/plain; (decoded 7bit)

Did anyone have try using DS1820 temp sensor connected with shield wire
for more than 50m distance to controller box and without have AC
interference ?

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2007\08\02@061155 by Russell McMahon

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part 1 326 bytes content-type:text/plain; format=flowed; charset=windows-1250; (decoded 7bit)

> Did anyone have try using DS1820 temp sensor connected with shield
> wire
> for more than 50m distance to controller box and without have AC
> interference ?

Using twisted pair will give you better noise immunity than a pair of
parallel wires.



               Russell




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2007\08\02@071446 by Ruben Jönsson

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I am using several DS1820 sensors in networks up to 400m with shielded wires.
BUT in the this case the shield is insulated from the data wires. Shield is
connected to to the grounded metal housing with EMC cable glands and the
electronics is insulated from the housing.

I am also using a system where shield and electronics isn't insulated. In these
systems we try to maximize cable length to 30m. 50m would be too much I think
but it depends on the cable and the driver. I am using a driver with active
pull up which helps a lot.

Regards / Ruben


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==============================
Ruben Jönsson
AB Liros Electronic
Box 9124, 200 39 Malmö, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
spam_OUTrubenTakeThisOuTspampp.sbbs.se
==============================

2007\08\02@073210 by Marc Nicholas

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I've done close to that distance using Cat5 twisted
pair....interestingly enough, the device I was measuring the
temperature of was a large "in window" air conditioner -- lots of EMI!

This setup was parasite powered, for what its worth.

-marc

On 8/2/07, cllow2020 <.....cllow2020KILLspamspam@spam@163.com> wrote:
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> -

2007\08\02@074429 by cllow2020

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Thanks Ruben,
I'm using shielded wire where shielded net is direct connected to Vcc+5v, inner wire is data signal, it desn't "sound " good enough for pulse data transition. This shield wire are tie-up with some AC shunt motor supply which drain amp. How to add driver on signal line where this signal are bi-direction, I normally use 4k7 pullup only direct to PIC port.



{Original Message removed}

2007\08\02@075319 by Dario Greggio

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cllow2020 wrote:

>I normally use 4k7 pullup only direct
> to PIC port.

I'd make some tests with 470 ohm: within specs on PIC's side, and I
guess on the peripheral's too...
This should increase range.


--
Ciao, Dario

2007\08\02@084122 by Ruben Jönsson

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Hi,

The first article in this PDF describes the circuit I use.

<http://www.edn.com/contents/images/3499di.pdf>

The article is somewhat unclear about the pullup though. The active pullup is
achieved by making the input an output and setting it low in order to make Q2
switch on Q1. This must be done in software just when you have sent a short
pulse on the dataline with Q3 either during reading or writing a "1" slot. This
means that you need one bidirectional I/O pin and one output only.

The circuit is also short circuit proof since it switches off the active pullup
if the dataline is pulled low enough.

I also use 510 ohms pullup instead of the 4.7k in the circuit. Instead of the
D1 in the circuit I have a protection circuit with small resistors, a tvs diode
and some shottky diodes to disconnect the capacitance of the tvs diode from the
dataline. The oposite end of the data line (where the sensors are) is
terminated with a resistor and capacitor. This is also important to get the
long wires to work with the low pullup resistor and the active pullup circuit.

I use the sensors with parasitic power but I can also use DS2409 lan couplers
that is powered with 5V and drive these with the same circuit.

We havn't had anyone break yet and we have made thousands.

/Ruben

> Thanks Ruben,
> I'm using shielded wire where shielded net is direct connected to Vcc+5v, inner
> wire is data signal, it desn't "sound " good enough for pulse data transition.
> This shield wire are tie-up with some AC shunt motor supply which drain amp. How
> to add driver on signal line where this signal are bi-direction, I normally use
> 4k7 pullup only direct to PIC port.
>
>
>
> {Original Message removed}

2007\08\02@094300 by Dave Tweed

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Marc Nicholas <geekythingspamKILLspamgmail.com> wrote:
> I've done close to that distance using Cat5 twisted
> pair....interestingly enough, the device I was measuring the
> temperature of was a large "in window" air conditioner -- lots of EMI!

I'm curious -- why should there be lots of EMI? AIUI, these units
tend to use induction motors exclusively, for both compressor and
fan, which are fairly "clean" as far as EMI goes.

Modern units probably use SSRs to turn the motors on and off, which
would switch on at zero voltage and switch off at zero current, and
this should also be fairly clean as far as EMI.

-- Dave Tweed

2007\08\02@104539 by Alan B. Pearce

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>I'm curious -- why should there be lots of EMI? AIUI, these units
>tend to use induction motors exclusively, for both compressor and
>fan, which are fairly "clean" as far as EMI goes.

I tend to work on the basis that such units have big fat cables, so if they
are not generating EMC/EMI themselves, then there is a big conduit bringing
such interference from somewhere that does generate it, and radiate where it
is not wanted.

2007\08\04@011734 by cllow2020

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part 1 1399 bytes content-type:text/plain; (decoded 7bit)

I intend to use DS1820 at an environment for mountain plantation area(
not green house, is open area). Where there are auto control of temp for
water cooling, lighting control at night-time and chemical water spray.
Challenge is the tempreture sensor have to tie-up with 60A AC power
cables which provide 5 units of motor each 5 hp and some lights.

The best way is to split into 5's location area with 5 individual
controller box, each controller handle ~ diameter of 60m area.  
But sadly to said is 5 times costly.

this project is at green tea plantation and flower plantation at
mountain area.

Thanks for all info.

Best regards
cllow2020


{Original Message removed}


'[PIC] DS1820 wire how long can it go ?'
2008\06\09@093808 by Nicola Perotto
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part 1 154 bytes content-type:text/plain; charset=windows-1250; format=flowed (decoded 7bit)


Nokia 3310 Lcd Thermometer using DS18B20 and a 12F629

http://www.electronics-lab.com/projects/mcu/013/index.html





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2008\06\09@111830 by Vasile Surducan

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On 8/3/07, cllow2020 <.....cllow2020KILLspamspam.....163.com> wrote:
> I intend to use DS1820 at an environment for mountain plantation area(
> not green house, is open area). Where there are auto control of temp for
> water cooling, lighting control at night-time and chemical water spray.


> Challenge is the tempreture sensor have to tie-up with 60A AC power
> cables which provide 5 units of motor each 5 hp and some lights.

If "tie-up" means for you using the same cable for AC and sensor, it's
about a wrong design and  not a challenge. If it's something else
please excuse my poor english. The DS18B20 is working without any
active pullup in a 50m chain using CAT5 cable where data is twisted
with GND in one pair and VCC is twisted with GND in the second
pair.The twisted pair has lower capacitance than shielded cable, and
is much better.

Vasile

2008\06\09@222231 by cllow2020(gmail)

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there is some difference between DS18B20 & DS1820, as far as I tried
DS18B20, with 30M have to pullup till 470 ohm even with cat5.
software...impact, well

"tie-up" means cable-tie up , no metal contact, along with 415V@60A 3phase
power cables 50m away.


--------------------------------------------------
From: "Vasile Surducan" <EraseMEpiclist9spam_OUTspamTakeThisOuTgmail.com>
Sent: Monday, June 09, 2008 11:18 PM
To: "Microcontroller discussion list - Public." <piclistspamspam_OUTmit.edu>
Subject: Re: [PIC] DS1820 wire how long can it go ?

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> --

2008\06\10@015211 by Vasile Surducan

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On 6/10/08, cllow2020(gmail) <KILLspamcllow2020KILLspamspamgmail.com> wrote:
> there is some difference between DS18B20 & DS1820, as far as I tried
> DS18B20, with 30M have to pullup till 470 ohm even with cat5.
> software...impact, well
>
> "tie-up" means cable-tie up , no metal contact, along with 415V@60A 3phase
> power cables 50m away.
>

 AFIK here is forbidden to carry a signal and a power cable one near
the other, but if this is the requirement, forgot about 1 wire bus and
use a serious RS485.

greetings,
Wesley (Vasile)

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