Hello Jan,
thanks for the swift and in-depth reply to my problem:
On 12/04/2016 07:31 PM, Jan Kandziora wrote:
Am 04.12.2016 um 12:07 schrieb Martin Patzak (GMX):
I am experiencing delays and also time-outs when reading temperatures of
very very close to and equal to 85 degrees Celsius.
This is a complicated situation as 85°C is the default power-up value
the sensor uses. When you have power failures during the conversion, you
cannot tell it apart from a valid 85°C reading.
Oh, I see
My application is a heating system, where a wood burning oven heats up
two 800l buffer containers of water to a max temperature of 95 degree
Celsius.
Every 30s simultaneous is written, followed by a two second wait, before
starting reading back the temperatures sequentially.
Please update to owfs-3.1p4. It has a new "latesttemp" node, which is
meant for exactly this setup. Trigger simulatenous/temperature, wait a
second in your user program, then read all the temperature values
sampled from the "latesttemp" node.
Thanks for pointing out, that there are changes in the latest version,
that a relevant to the problem.
So, I did update, and gave it a try with simple testprogramm accessing
the latesttemp node.
For testing I read only two sensors. First the one that is close to 85
deg C and another one just for seeing the next read done.
The new node works fine too, but unfortunately I get an error, when a
sensor is right at 85 deg C:
/Traceback (most recent call last)://
// File "read_a_temp.py", line 15, in <module>//
// sensed = op.read('/28.676A20060000/latesttemp')//
// File "/home/mnm/pyownet/src/pyownet/protocol.py", line 545, in read//
// raise OwnetError(-ret, self.errmess[-ret], path)//
//pyownet.protocol.OwnetError: [Errno 22] legacy - Invalid transaction:
'/28.676A20060000/latesttemp'
/here is the python test-code:
/import time//
//from pyownet import protocol//
//
//op = protocol.proxy("razmaban",port=4304)//
//
//
//op.write('/simultaneous/temperature', '1')//
//
//time.sleep(1) # give the sensors time to convert their temps//
//
//print 'reading now...'//
//
//sensed = op.read('/28.676A20060000/latesttemp')//
//print sensed//
//
//sensed = op.read('/28.DD5915020000/latesttemp')//
//print sensed//
//
/
First time I have seen this error message, what does it mean?
I am aware that the 18S20 did report an error with 85 deg C, but the
18B20 should not do this.
Is there something in owfs that would re-read in case a value of exactly
85 deg C would be returned by a sensor?
Yes, there is a try-again-mechanism when you read the "temperature" and
"temperatureXX" nodes. Update and use "latesttemp" instead.
Please see the updated manpages, too.
I did install owfs-doc 3.1p4, but I searched for 'latesttemp' and for
'simultaneous', but I couldn't find anything.
Where do I find the updated information?
Cheers Martin
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