New Release 2.8p7

Release Notes 2.8p7

1. Add support for the EDS0071 4-wire RTD temperature module
2. Add provisional support for EDS0064 EDS0065 EDS0066 EDS0067 EDS0068
3. Fix an error is remote alias calls.
4. Add a delay and retry on owserver links to allow owserver to start
up and open a listening socket

See https://www.embeddeddatasystems.com/1-Wire-Interface-for-4-Wire-RTD_p_165.html

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Dreaded 85 degrees C read from DS18B20 located outside

Hi list,

Apologies for the slightly off-topic message but I figured someone here 
may have some suggestions for me on this non-owfs issue I am having...

I have a DS18B20 sensor located outside. It is in a location that is 
safe from water (unless it rains horizontally). My bus master reaches 
this sensor through a cat5 bus that has about 10 more sensors. The 
sensor, its pins, and the small PCB the sensor is soldered to, are all 
exposed (to wind and humidity, but not to direct water). Parasitic 
powered, and Vcc pin is floating (not connected to ground). This setup 
has been pretty stable (no 1-wire errors or bad temperature readouts in 
6 months of operation).

Last night there was heavy rain and thunderstorms in the area and for a 
period of about two hours I was getting the dreaded 85 degrees C from 
this sensor. All other sensors were fine during this time and did not 
report 85 degrees. The problem fixed itself a bit after rain and 
thunderstorms passed.

I think it is humidity what causes the 85 degrees C readout since we've 
had a few warm and humid days/nights recently (but no rain) and I've 
gotten a few 85 degrees C readouts here and there from the same sensor. 
But nothing like last night when I consistently got 85 degrees C 
readouts for about two hours.

Next time this happens I plan on grounding Vcc to see if that helps, but 
I also wanted to ask the list for theories on what could be causing 
these 85 degrees C readouts when it is humid (or when there are 
thunderstorms in the area).

Re: Dreaded 85 degrees C read from DS18B20 located outside

The sensor returns 85/185 at startup if it has not had a chance to do
a complete convert_t by the time you read_t on it. My guess is its
either shorting out somewhere and resetting or not getting enough
juice to handle the convert_t.

Are the other sensors ok? Are any of the other ones also outside?

I have my outside sensor covered in silicone. Its non-conductive,
waterproof, etc. It will delay temp changes slightly as it has a
higher specific heat capacity than air though, but not by much ;) I
have heard of other people using wax for this also as it is easier to
remove if needed but if you live in Texas it might melt off by itself
if left in the sun in summer.

Hope that helps.
-Guil

On Tue, Mar 1, 2011 at 11:54 AM, Eloy Paris <peloy <at> chapus.net> wrote:
> Hi list,
>
> Apologies for the slightly off-topic message but I figured someone here
> may have some suggestions for me on this non-owfs issue I am having...
>
> I have a DS18B20 sensor located outside. It is in a location that is
> safe from water (unless it rains horizontally). My bus master reaches
> this sensor through a cat5 bus that has about 10 more sensors. The
> sensor, its pins, and the small PCB the sensor is soldered to, are all
> exposed (to wind and humidity, but not to direct water). Parasitic
> powered, and Vcc pin is floating (not connected to ground). This setup
> has been pretty stable (no 1-wire errors or bad temperature readouts in

Re: Dreaded 85 degrees C read from DS18B20 located outside

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Re: Dreaded 85 degrees C read from DS18B20 located outside

Dnia 2011-03-01, wto o godzinie 12:54 -0500, Eloy Paris pisze:

> If grounding Vcc does not help I think my next step should be to protect 
> from the elements the sensor, its pins, and the small PCB. Any ideas on 
> how to accomplish this; is there some coating I can spray on the 
> sensor's pins and on the PCB that will protect them from humidity?

I soldered some wire(20cm) directly to DS18b20 pins with VCC and GND
together and put it in a heatshrink tube and placed the connector to the
rest of the network inside.

Maxim suggests connecting Vcc do GND when using parasite power. Maybe
you have DS18B20+PAR with Vcc and GND already connected internally.

--

-- 
p4trykx

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Re: Dreaded 85 degrees C read from DS18B20 located outside

Dnia 2011-03-01, wto o godzinie 12:54 -0500, Eloy Paris pisze:

> If grounding Vcc does not help I think my next step should be to protect 
> from the elements the sensor, its pins, and the small PCB. Any ideas on 
> how to accomplish this; is there some coating I can spray on the 
> sensor's pins and on the PCB that will protect them from humidity?

I soldered some wire(20cm) directly to DS18b20 pins with VCC and GND
together and put it in a heatshrink tube and placed the connector to the
rest of the network inside.

Maxim suggests connecting Vcc do GND when using parasite power maybe you
have ds18b20par with Vcc and GND already connected internally.

--

-- 
p4trykx 

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Re: Dreaded 85 degrees C read from DS18B20 located outside

That's interesting that the humidity effects only one sensor, not the whole bus.

The HobbyBoards people used a special coating for their PCBs that
seems effective.

What is the design of your sensor -- what does the PCB do?

Paul

On Tue, Mar 1, 2011 at 12:54 PM, Eloy Paris <peloy <at> chapus.net> wrote:
> Hi list,
>
> Apologies for the slightly off-topic message but I figured someone here
> may have some suggestions for me on this non-owfs issue I am having...
>
> I have a DS18B20 sensor located outside. It is in a location that is
> safe from water (unless it rains horizontally). My bus master reaches
> this sensor through a cat5 bus that has about 10 more sensors. The
> sensor, its pins, and the small PCB the sensor is soldered to, are all
> exposed (to wind and humidity, but not to direct water). Parasitic
> powered, and Vcc pin is floating (not connected to ground). This setup
> has been pretty stable (no 1-wire errors or bad temperature readouts in
> 6 months of operation).
>
> Last night there was heavy rain and thunderstorms in the area and for a
> period of about two hours I was getting the dreaded 85 degrees C from
> this sensor. All other sensors were fine during this time and did not
> report 85 degrees. The problem fixed itself a bit after rain and
> thunderstorms passed.
>
> I think it is humidity what causes the 85 degrees C readout since we've
> had a few warm and humid days/nights recently (but no rain) and I've
> gotten a few 85 degrees C readouts here and there from the same sensor.
> But nothing like last night when I consistently got 85 degrees C
> readouts for about two hours.
>
> Next time this happens I plan on grounding Vcc to see if that helps, but
> I also wanted to ask the list for theories on what could be causing
> these 85 degrees C readouts when it is humid (or when there are
> thunderstorms in the area).
>
> If grounding Vcc does not help I think my next step should be to protect
> from the elements the sensor, its pins, and the small PCB. Any ideas on
> how to accomplish this; is there some coating I can spray on the
> sensor's pins and on the PCB that will protect them from humidity?
>
> Thanks in advance for any suggestions.
>
> Cheers,
>
> Eloy Paris.-
>
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> Real-Time with Splunk. Collect, index and harness all the fast moving IT data
> generated by your applications, servers and devices whether physical, virtual
> or in the cloud. Deliver compliance at lower cost and gain new business
> insights. http://p.sf.net/sfu/splunk-dev2dev
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Re: Dreaded 85 degrees C read from DS18B20 located outside

Hi Eloy,

I am using a mix of DS18B20 and DS18S20, my experience has been that
they will work reliably when powered and also in parasitic mode if you
link Gnd and Vdd, but if you don't they are a bit hit and miss on a
sensor by sensor basis, one may work fine but another reads 85.  Also
when floating they don't seem to be sure if they are powered or not,
some say they are and others say they are not. 

My advice therefore is to link Vdd to Gnd.  Why it should be affected by
humidity or thunder storms I don't know, but given that they seem to be
a bit 'on the edge' with Vdd floating I guess it may change the
resistance or capacitance slightly and push it over the edge.  The
capacitance effect will also be influenced by objects and materials in
close proximity.

Also does anyone know if the 85 reading is irrespective of units?  My
setup is in degrees C, but if it was in F would the error still be 85 or
would it be 185F?  If it stays at 85 irrespective it is a way to
differentiate an error from a genuine 85 reading.

Best of luck
Mick

On Tue, 2011-03-01 at 12:54 -0500, Eloy Paris wrote:
> Hi list,
> 
> Apologies for the slightly off-topic message but I figured someone here 
> may have some suggestions for me on this non-owfs issue I am having...
> 
> I have a DS18B20 sensor located outside. It is in a location that is 
> safe from water (unless it rains horizontally). My bus master reaches 
> this sensor through a cat5 bus that has about 10 more sensors. The 
> sensor, its pins, and the small PCB the sensor is soldered to, are all 
> exposed (to wind and humidity, but not to direct water). Parasitic 
> powered, and Vcc pin is floating (not connected to ground). This setup 
> has been pretty stable (no 1-wire errors or bad temperature readouts in 
> 6 months of operation).
> 
> Last night there was heavy rain and thunderstorms in the area and for a 
> period of about two hours I was getting the dreaded 85 degrees C from 
> this sensor. All other sensors were fine during this time and did not 
> report 85 degrees. The problem fixed itself a bit after rain and 
> thunderstorms passed.
> 
> I think it is humidity what causes the 85 degrees C readout since we've 
> had a few warm and humid days/nights recently (but no rain) and I've 
> gotten a few 85 degrees C readouts here and there from the same sensor. 
> But nothing like last night when I consistently got 85 degrees C 
> readouts for about two hours.
> 
> Next time this happens I plan on grounding Vcc to see if that helps, but 
> I also wanted to ask the list for theories on what could be causing 
> these 85 degrees C readouts when it is humid (or when there are 
> thunderstorms in the area).
> 
> If grounding Vcc does not help I think my next step should be to protect 
> from the elements the sensor, its pins, and the small PCB. Any ideas on 
> how to accomplish this; is there some coating I can spray on the 
> sensor's pins and on the PCB that will protect them from humidity?
> 
> Thanks in advance for any suggestions.
> 
> Cheers,
> 
> Eloy Paris.-

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Re: Dreaded 85 degrees C read from DS18B20 located outside

Hi Mick,

On 03/02/2011 04:41 AM, Mick Sulley wrote:

> Hi Eloy,
>
> I am using a mix of DS18B20 and DS18S20, my experience has been that
> they will work reliably when powered and also in parasitic mode if you
> link Gnd and Vdd, but if you don't they are a bit hit and miss on a
> sensor by sensor basis, one may work fine but another reads 85.  Also
> when floating they don't seem to be sure if they are powered or not,
> some say they are and others say they are not.
>
> My advice therefore is to link Vdd to Gnd.

I think this is sound advice even if things have worked well for me with 
12 sensors that all have Vdd floating.

> Why it should be affected by
> humidity or thunder storms I don't know, but given that they seem to be
> a bit 'on the edge' with Vdd floating I guess it may change the
> resistance or capacitance slightly and push it over the edge.  The
> capacitance effect will also be influenced by objects and materials in
> close proximity.

Thanks for the insight! Good stuff in this thread; I'm glad I asked even 
if it was a bit off-topic for owfs 

> Also does anyone know if the 85 reading is irrespective of units?  My
> setup is in degrees C, but if it was in F would the error still be 85 or
> would it be 185F?  If it stays at 85 irrespective it is a way to
> differentiate an error from a genuine 85 reading.

The 1820 only reports in degrees Celsius and it is owfs the one 
providing degrees F capabilities, right? If that is the case then I 
would expect 85 C to be reported by owfs in the equivalent degrees F.

So yes, that is a good question -- how does one tell the difference 
between true 85 C and error 85 C? (not that I am expecting to read a 
true 85 C, although I suspect things get pretty hot in an attic in the 
summer).

Cheers,

Eloy Paris.-

>
> Best of luck
> Mick
>
> On Tue, 2011-03-01 at 12:54 -0500, Eloy Paris wrote:
>> Hi list,
>>
>> Apologies for the slightly off-topic message but I figured someone here
>> may have some suggestions for me on this non-owfs issue I am having...
>>
>> I have a DS18B20 sensor located outside. It is in a location that is
>> safe from water (unless it rains horizontally). My bus master reaches
>> this sensor through a cat5 bus that has about 10 more sensors. The
>> sensor, its pins, and the small PCB the sensor is soldered to, are all
>> exposed (to wind and humidity, but not to direct water). Parasitic
>> powered, and Vcc pin is floating (not connected to ground). This setup
>> has been pretty stable (no 1-wire errors or bad temperature readouts in
>> 6 months of operation).
>>
>> Last night there was heavy rain and thunderstorms in the area and for a
>> period of about two hours I was getting the dreaded 85 degrees C from
>> this sensor. All other sensors were fine during this time and did not
>> report 85 degrees. The problem fixed itself a bit after rain and
>> thunderstorms passed.
>>
>> I think it is humidity what causes the 85 degrees C readout since we've
>> had a few warm and humid days/nights recently (but no rain) and I've
>> gotten a few 85 degrees C readouts here and there from the same sensor.
>> But nothing like last night when I consistently got 85 degrees C
>> readouts for about two hours.
>>
>> Next time this happens I plan on grounding Vcc to see if that helps, but
>> I also wanted to ask the list for theories on what could be causing
>> these 85 degrees C readouts when it is humid (or when there are
>> thunderstorms in the area).
>>
>> If grounding Vcc does not help I think my next step should be to protect
>> from the elements the sensor, its pins, and the small PCB. Any ideas on
>> how to accomplish this; is there some coating I can spray on the
>> sensor's pins and on the PCB that will protect them from humidity?
>>
>> Thanks in advance for any suggestions.
>>
>> Cheers,
>>
>> Eloy Paris.-
>
>
>
>
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> generated by your applications, servers and devices whether physical, virtual
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> insights. http://p.sf.net/sfu/splunk-dev2dev
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Re: Dreaded 85 degrees C read from DS18B20 located outside

> Hhmmm. Interesting. Tips like these is exactly what I am after, so thanks a
> bunch for that.
>
> I like the idea of covering the sensor (or parts of the sensor and the PCB)
> with silicone. Do you remember what specific product you used (was it a
> spray, or just one of those tubes you buy at HomeDepot or Lowe's that you
> apply with a gun)?

Yes, I just got a tube of silicone I had laying around the house and
encased the whole thing in it. If I remember the tech sheet correctly,
the newer DS18b20's are entirely waterproof (old ones had issues) so
you really only need to encase the leads. I did the whole thing as the
sensor is pulling the temp read off of the ground wire anyways so
might as well be safe.

> I also like the idea of using wax. I obviously had not thought about it. I
> suppose that in that case you melt the wax (like from a candle) in a pot and
> then dip the PCB into it. Is that they way people would do it?

I've seen it done for potting electronics on ROV's. In that case they
had the electronics in a small plastic enclosure and just filled the
enclosure with wax when done.

> I also found about "conformal coating" while doing some searches last night.
> Guess that is the official name of what I am after. There are products to do
> conformal coating, although nothing you can find at your local hardware
> store, which is why I'd prefer to go with one of the two methods you
> mentioned.

I think thats what Hobby-Boards uses, might be worth sending them an email.

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