Sophana,

I dug up some old code that still works and worked through owfs instead 
of oypython. changing it to shell language it would look like:

echo -n 1 > top/simultaneous/temperature
date
for i in $owidlist
do
   cat top/$i/temperature
   echo
done
date

I would try taking all the unpowered sensors off the hub and see if it 
still doesn't work. I am running crusty old code on my shuttle pc 
running older ubuntu, so I doubt it is an upgrade issue.

jerry

Sophana K wrote:
> When you "set the simultaneous convert", do you mean you write  1 to
> the top/simulaneous/temperature?
> 
> something like this?:
> echo 1 > simultaneous/temperature
> cat 1F.C4DC03000000/aux/28.C4027E010000/temperature
> cat 1F.C4DC03000000/aux/28.0D337E010000/temperature
> 
> This doesn't work for me, it is slow.
> 
> Are you driving the "local" simultaneous files (like
> 1F.C4DC03000000/aux/simultaneous/temperature)
> 
> What version of owfs are you using?
> Do you think I should upgrade?
> 
> I'm also running a hvac system which currently has period of about 20
> seconds. Which is still ok for now.
> But I'm going to extend it with about 10 more sensors, and I would
> like it to be more reactive when driving the 4 way valves.
> 
> What platform are you using? I'm considering upgrading to an low power
> intel atom (or d510) based PC or maybe dedicating a sheeva plug for
> the hvac. My current router (asus wl500g deluxe) doesn't have a real
> time clock so I need the internet at boot time just to get the time
> for my hvac system to work.
> 
> Thanks for your help
> 
> On Wed, Jan 27, 2010 at 6:30 PM, Jerry Scharf
> <[email protected]> wrote:
>> Sophana,
>>
>> First, I drive my sensors from python through owserver, so a simple
>> example probably won't help you. I don't think that "on their own
>> segment" is enough because the sensor can't know that, but this is
>> beyond my level of knowledge about 1-wire.
>>
>> What I do is set the simultaneous convert and then read the sensors
>> sequentially. The master can only do one thing at at time, so I didn't
>> see much value in doing any threading for my simple problem. The timing
>> definitely shows that they are not doing the conversion at read time.
>> It's easy to compare by just skipping the simultaneous and doing the
>> sequential read.
>>
>> I'm running a HVAC system, so readings every 30 seconds is fine. Not
>> what I would call a high speed operation.
>>
>> hope that helps,
>> jerry
>>
>> Sophana K wrote:
>>> Hi
>>>
>>> I made the tests on powered sensors.
>>> Some other sensors are not powered but they are "alone" on their own
>>> hub segments.
>>> You don't need to write to the simultaneous/temperature file?
>>> Just do parallel access to owserver?
>>> Or do you do both?
>>> Can you give an example of access sequence you are doing?
>>> Does owfs on top of owserver limit parallel access to the values?
>>> Should I try directly with threads inside my python program to access
>>> owserver in parallel?
>>>
>>> Thanks
>>>
>>> On Wed, Jan 27, 2010 at 5:10 PM, Jerry Scharf
>>> <[email protected]> wrote:
>>>> Sophana,
>>>>
>>>> I am sure this works. I have a hub (not a switch) and do simultaneous
>>>> reads for my 30+ temp sensors. Do you have separate power or are you
>>>> running in parasitic mode. I am fairly certain you can not do
>>>> simultaneous reads with parasitic power.
>>>>
>>>> jerry
>>>>
>>>> Sophana K wrote:
>>>>> On Mon, Jan 11, 2010 at 4:35 PM, Paul Alfille <[email protected]> 
>>>>> wrote:
>>>>>
>>>>>> It's easy to do if the segments are on different bus masters. Just read 
>>>>>> in a
>>>>>> different thread or program since only the bus master is locked. An
>>>>>> asynchronous read property for temperature is also possible.
>>>>> I tried this, but it doesn't seem to work.
>>>>> I made the test through owfs on top of owserver -u with a small script
>>>>> making simultaneous accesses to different sensors. It is as slow as
>>>>> reading the sensors sequentialy.
>>>>> Are you sure about this feature?
>>>>>
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