long wire problems using DS1820 and BS2P
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> Hi all,
>
> I'm using a BS2P and a DS1820 temperature sensor. On the workbench (with
> short cables) it works perfect, however when I connect the DS1820 on a
> cable of about 20 metres, it's not working at all !!! The cable that i'm
> using is a UTP cat5 cable. I'm not using the parasite power feature of the
> DS1820 and i'm powering the DS1820 by using one wire for the +5V.
>
> I've been searching for weeks now, i've read all the related documents of
> Dallas semiconductor but nothing seems to work with the longer cables.
>
> Does someone have experience with the DS1820, BS2P and quite long cables?
> Is there a way to solve this problem?
>
> I really hope someone can help me with this
>
> Many thanks to all
>
> Wilbert
>
> I'm using a BS2P and a DS1820 temperature sensor. On the workbench (with
> short cables) it works perfect, however when I connect the DS1820 on a
> cable of about 20 metres, it's not working at all !!! The cable that i'm
> using is a UTP cat5 cable. I'm not using the parasite power feature of the
> DS1820 and i'm powering the DS1820 by using one wire for the +5V.
>
> I've been searching for weeks now, i've read all the related documents of
> Dallas semiconductor but nothing seems to work with the longer cables.
>
> Does someone have experience with the DS1820, BS2P and quite long cables?
> Is there a way to solve this problem?
>
> I really hope someone can help me with this
>
> Many thanks to all
>
> Wilbert
Comments
I'll soon use this kind of temperature sensor to control my central heating
system.
I think you should use shielded cable. The UTP is not shielded. I know it
works for networks, but maybe with differential signals (I'm not sure it's
differential).
Hope this is the track to the solution...
Phil.
Subject: [noparse][[/noparse]basicstamps] long wire problems using DS1820 and BS2P
>
> > Hi all,
> >
> > I'm using a BS2P and a DS1820 temperature sensor. On the workbench (with
> > short cables) it works perfect, however when I connect the DS1820 on a
> > cable of about 20 metres, it's not working at all !!! The cable that i'm
> > using is a UTP cat5 cable. I'm not using the parasite power feature of
the
> > DS1820 and i'm powering the DS1820 by using one wire for the +5V.
> >
> > I've been searching for weeks now, i've read all the related documents
of
> > Dallas semiconductor but nothing seems to work with the longer cables.
> >
> > Does someone have experience with the DS1820, BS2P and quite long
cables?
> > Is there a way to solve this problem?
> >
> > I really hope someone can help me with this
> >
> > Many thanks to all
> >
> > Wilbert
Thanks for your fast reply. The problem is that the cables are
already installed in my house and i've no possibility to change them.
Best regards
Wilbert
--- In basicstamps@y..., "Philippe Derenne" <derennep@s...> wrote:
> Hi Wilbert,
>
> I'll soon use this kind of temperature sensor to control my central
heating
> system.
> I think you should use shielded cable. The UTP is not shielded. I
know it
> works for networks, but maybe with differential signals (I'm not
sure it's
> differential).
> Hope this is the track to the solution...
>
> Phil.
>
> Subject: [noparse][[/noparse]basicstamps] long wire problems using DS1820 and BS2P
>
>
> >
> > > Hi all,
> > >
> > > I'm using a BS2P and a DS1820 temperature sensor. On the
workbench (with
> > > short cables) it works perfect, however when I connect the
DS1820 on a
> > > cable of about 20 metres, it's not working at all !!! The cable
that i'm
> > > using is a UTP cat5 cable. I'm not using the parasite power
feature of
> the
> > > DS1820 and i'm powering the DS1820 by using one wire for the
+5V.
> > >
> > > I've been searching for weeks now, i've read all the related
documents
> of
> > > Dallas semiconductor but nothing seems to work with the longer
cables.
> > >
> > > Does someone have experience with the DS1820, BS2P and quite
long
> cables?
> > > Is there a way to solve this problem?
> > >
> > > I really hope someone can help me with this
> > >
> > > Many thanks to all
> > >
> > > Wilbert
> > Hi all,
>>
>> I'm using a BS2P and a DS1820 temperature sensor. On the workbench (with
>> short cables) it works perfect, however when I connect the DS1820 on a
>> cable of about 20 metres, it's not working at all !!! The cable that i'm
>> using is a UTP cat5 cable. I'm not using the parasite power feature of the
>> DS1820 and i'm powering the DS1820 by using one wire for the +5V.
>>
>> I've been searching for weeks now, i've read all the related documents of
>> Dallas semiconductor but nothing seems to work with the longer cables.
>>
>> Does someone have experience with the DS1820, BS2P and quite long cables?
>> Is there a way to solve this problem?
>>
>> I really hope someone can help me with this
>>
>> Many thanks to all
>>
>
> > Wilbert
The signals used in 1-wire protocol are very fast (~50 microseconds)
and use a passive pullup for the high state. The capacitance of the
cable slows the signal down. The signals is comparable to a weak
20kbaud RS232. One-wire is not really meant for long cables, and
it really surprises me that they promote it for that kind of network.
That said, you can try to speed up the transitions by using the
lowest possible resistance for the pullup resistor.
-- best regards
Tracy Allen
electronically monitored ecosystems
http://www.emesystems.com
mailto:tracy@e...
If you look at the Dallas semiconductor sheets, they even promote the
1-wire protocol that it can be used for lengths more than 200
meters ?!
I will try with a stronger pull up resistor and will let you know if
it works.
Thanks a lot for the good advice !!!!
Wilbert
--- In basicstamps@y..., Tracy Allen <tracy@e...> wrote:
> At 5:44 PM +0100 7/20/01, wilbert.ingels@l... wrote:
> > > Hi all,
> >>
> >> I'm using a BS2P and a DS1820 temperature sensor. On the
workbench (with
> >> short cables) it works perfect, however when I connect the
DS1820 on a
> >> cable of about 20 metres, it's not working at all !!! The cable
that i'm
> >> using is a UTP cat5 cable. I'm not using the parasite power
feature of the
> >> DS1820 and i'm powering the DS1820 by using one wire for the +5V.
> >>
> >> I've been searching for weeks now, i've read all the related
documents of
> >> Dallas semiconductor but nothing seems to work with the longer
cables.
> >>
> >> Does someone have experience with the DS1820, BS2P and quite
long cables?
> >> Is there a way to solve this problem?
> >>
> >> I really hope someone can help me with this
> >>
> >> Many thanks to all
> >>
> >
> > > Wilbert
>
> The signals used in 1-wire protocol are very fast (~50
microseconds)
> and use a passive pullup for the high state. The capacitance of the
> cable slows the signal down. The signals is comparable to a weak
> 20kbaud RS232. One-wire is not really meant for long cables,
and
> it really surprises me that they promote it for that kind of
network.
>
> That said, you can try to speed up the transitions by using the
> lowest possible resistance for the pullup resistor.
>
> -- best regards
> Tracy Allen
> electronically monitored ecosystems
> http://www.emesystems.com
> mailto:tracy@e...
>At 5:44 PM +0100 7/20/01, wilbert.ingels@l... wrote:
> > > Hi all,
> >>
> >> I'm using a BS2P and a DS1820 temperature sensor. On the workbench (with
> >> short cables) it works perfect, however when I connect the DS1820 on a
> >> cable of about 20 metres, it's not working at all !!! The cable that i'm
> >> using is a UTP cat5 cable. I'm not using the parasite power feature of the
> >> DS1820 and i'm powering the DS1820 by using one wire for the +5V.
> >>
> >> I've been searching for weeks now, i've read all the related documents of
> >> Dallas semiconductor but nothing seems to work with the longer cables.
> >>
> >> Does someone have experience with the DS1820, BS2P and quite long cables?
> >> Is there a way to solve this problem?
>
>The signals used in 1-wire protocol are very fast (~50 microseconds)
>and use a passive pullup for the high state. The capacitance of the
>cable slows the signal down. The signals is comparable to a weak
>20kbaud RS232. One-wire is not really meant for long cables, and
>it really surprises me that they promote it for that kind of network.
>
>That said, you can try to speed up the transitions by using the
>lowest possible resistance for the pullup resistor.
You *might* also use a pair of resistors (or a pot) as a divider, as
diagrammed below, to place the voltage closer to the transition
point. Select the resistors to just barely, but reliably, pull the pin to
a high state. Works great for TTL at several MHz, but I really don't know
much about 1-wire stuff.
R1 R2
+V ---/\/\/\/\/\---|--\/\/\/\/\/\/--- 0V
|
|
| to pin to be "pulled up."
Jim H
rise and fall. The R is fixed at 4.7K and as you add more cable, you
add more C.
Philips has a P82B715 bidirectional current amplifier which was
intended for use with their I2C devices. I have used a pair of
these, one at the processor, the other at some distant point and have
communicated with the DS1820 over distances of 1000 feet (not with a
BS2P). However, I do share Tracy's thoughts on such distances.
Great for an experiment, but I wouldn't bet the house.
The idea of the current amplifier is as noted by Tracy. I was able
to reduce the R to 200 Ohms and thus tolerate that much more C.
Peter H Anderson, http://www.phanderson.com
--- In basicstamps@y..., wilbert.ingels@l... wrote:
>
> > Hi all,
> >
> > I'm using a BS2P and a DS1820 temperature sensor. On the
workbench (with
> > short cables) it works perfect, however when I connect the DS1820
on a
> > cable of about 20 metres, it's not working at all !!! The cable
that i'm
> > using is a UTP cat5 cable. I'm not using the parasite power
feature of the
> > DS1820 and i'm powering the DS1820 by using one wire for the +5V.
> >
> > I've been searching for weeks now, i've read all the related
documents of
> > Dallas semiconductor but nothing seems to work with the longer
cables.
> >
> > Does someone have experience with the DS1820, BS2P and quite long
cables?
> > Is there a way to solve this problem?
> >
> > I really hope someone can help me with this
> >
> > Many thanks to all
> >
> > Wilbert
Thanks a lot for the advices and yes, the RC time constant was the
problem !!! I've reduced the value of the pull up resistor and it is
working now. I'm using 6 DS1820 around my house and on some lines, i
had to reduce the resistor below 2K (on 1 line, i've installed a
resistor of 1.2K)
Soo many thanks to all for the very good advices !!!!
Best regards
Wilbert
--- In basicstamps@y..., pha@p... wrote:
>
> The problem is the RC time constant causes the pulses to
expotentialy
> rise and fall. The R is fixed at 4.7K and as you add more cable,
you
> add more C.
>
> Philips has a P82B715 bidirectional current amplifier which was
> intended for use with their I2C devices. I have used a pair of
> these, one at the processor, the other at some distant point and
have
> communicated with the DS1820 over distances of 1000 feet (not with
a
> BS2P). However, I do share Tracy's thoughts on such distances.
> Great for an experiment, but I wouldn't bet the house.
>
> The idea of the current amplifier is as noted by Tracy. I was able
> to reduce the R to 200 Ohms and thus tolerate that much more C.
>
> Peter H Anderson, http://www.phanderson.com
>
> --- In basicstamps@y..., wilbert.ingels@l... wrote:
> >
> > > Hi all,
> > >
> > > I'm using a BS2P and a DS1820 temperature sensor. On the
> workbench (with
> > > short cables) it works perfect, however when I connect the
DS1820
> on a
> > > cable of about 20 metres, it's not working at all !!! The cable
> that i'm
> > > using is a UTP cat5 cable. I'm not using the parasite power
> feature of the
> > > DS1820 and i'm powering the DS1820 by using one wire for the
+5V.
> > >
> > > I've been searching for weeks now, i've read all the related
> documents of
> > > Dallas semiconductor but nothing seems to work with the longer
> cables.
> > >
> > > Does someone have experience with the DS1820, BS2P and quite
long
> cables?
> > > Is there a way to solve this problem?
> > >
> > > I really hope someone can help me with this
> > >
> > > Many thanks to all
> > >
> > > Wilbert