Paul,
Just to be clear, you are telling me that unless I supply power directly
to the thermometer sensors, I cannot expect simultaneous to help me
here. It might be possible for me to provide power to the sensors from
the hub itself, I will investigate that.
Jim
Paul Alfille wrote:
1. Simultaneous supposedly doesn't work with parasitic power -- there
is too great a draw on the data line.
2. There will always be a 1 second pause, but with simultaneous, only
once. I.e., you write to simultaneous once, and conversion is
triggered on all the temperature sensors, and after that second, all
the temperature values can be read directly from the chips.
Paul
On 5/25/06, Jim Duda <[EMAIL PROTECTED]> wrote:
FYI, I'm currently using owfs-2.3p6.
Jim
"Alfille, Paul H.,M.D." <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
Your understanding is correct.
I'll check the code.
I assume your sensors are separately powered, rather than parasytic.
Also, a minor point, that 750msec is actually 1sec, based on large
experience of
the 1-wire community.
Paul Alfille
-----Original Message-----
From: [EMAIL PROTECTED] on behalf of Jim Duda
Sent: Thu 5/25/2006 1:50 PM
To: [email protected]
Subject: [Owfs-developers] Question on Simultaneous
Can someone please help me with simultaneous?
My understanding is that writing a value to the
simultaneous/temperature file
will cause
a temperature conversion, but not incure a long delay in the write
operation, as
compared to reading the actual temperature.
I"m trying to insure that whenever I read a temperature value, I'm always
reading from the
cache, to avoid a long delay on the read response.
I'm running owserver without a -t parameter, so that should default to 10
seconds
for which data remains in the cache.
I have 4 thermometers on owfs, all of which are attached to a hub.
I have a perl script which does the following:
On odd seconds, it issues a write of "1" to all the
simultaneous/temperature
files
adjacent in the hierarchy to each thermometor. I'm assuming this
starts a
temperature conversion for each thermometer. I believe the typical time
for a temperature conversion is 750mS.
On even seconds, it issues a read of each temperature device. The
reading
of 4 devices appears to take 6 seconds. I was expecting the reads to be
much quicker, I'm assuming they should be coming from the cache.
I've also changed the delay between writing and reading to 2 seconds, but
I get the same behavior.
Is my understanding of "simultaneous" correct?
Thanks,
Jim
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