Well, Jim That is the accepted wisdom. I've never done the test. OWFS doesn't care, per se. Supposedly the current draw is too large, otherwise and the temperature voltage drops too much on the line.
You can also do other 1-wire communication during conversion, if the devices are powered. (Probably would need threads in your perl program to do that). Paul On 5/25/06, Jim Duda <[EMAIL PROTECTED]> wrote:
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 >> >> >> >> >> >> ------------------------------------------------------- >> All the advantages of Linux Managed Hosting--Without the Cost and Risk! >> Fully trained technicians. The highest number of Red Hat >> certifications in >> the hosting industry. Fanatical Support. Click to learn more >> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=107521&bid=248729&dat=121642 >> _______________________________________________ >> Owfs-developers mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/owfs-developers >> >> >> >> >> >> >> ------------------------------------------------------- >> All the advantages of Linux Managed Hosting--Without the Cost and Risk! >> Fully trained technicians. The highest number of Red Hat >> certifications in >> the hosting industry. Fanatical Support. Click to learn more >> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=107521&bid=248729&dat=121642 >> _______________________________________________ >> Owfs-developers mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/owfs-developers >> > > > ------------------------------------------------------- > All the advantages of Linux Managed Hosting--Without the Cost and Risk! > Fully trained technicians. The highest number of Red Hat certifications in > the hosting industry. Fanatical Support. Click to learn more > http://sel.as-us.falkag.net/sel?cmd=k&kid7521&bid$8729&dat1642 ------------------------------------------------------- All the advantages of Linux Managed Hosting--Without the Cost and Risk! Fully trained technicians. The highest number of Red Hat certifications in the hosting industry. Fanatical Support. Click to learn more http://sel.as-us.falkag.net/sel?cmd=lnk&kid=107521&bid=248729&dat=121642 _______________________________________________ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
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