DS9490R yields similar results. This time only a ground short is observed. Again, this seemed to read fine into a DS9490R using the TMEX API through LabVIEW.
Looking at the two datasheets, there is no way to avoid device-dependent code. There need to be three distinct values: temperature, tctemperature, and tcjctemperature. The reason for this is that the temperature in bytes 0-1 is formatted differently in the MSB. See below for summary for temp (DS1825) and CJC-compensated temp: Bit / DS1825 / MAX31850 0 - 2^-4 - Fault 1 - 2^-3 - Reserved 2 - 2^-2 - 2^-2 3 - 2^-1 - 2^-1 4 - 2^0 - 2^0 5 - 2^1 - 2^1 6 - 2^2 - 2^2 7 - 2^3 - 2^3 8 - 2^4 - 2^4 9 - 2^5 - 2^5 10 - 2^6 - 2^6 11 - S - 2^7 12 - S - 2^8 13 - S -2^9 14 - S - 2^10 15 - S - S Thus, you need to know whether you are looking for a value interpreted as a DS1825 or as a MAX31850. Because they are indistinguishable from software, you'd just know which one to read. This is the way that I wrote the routine on the LabVIEW program I wrote using TMEX API. You just have to know which value to read. Still, even with this, I cannot match up the value being read with owfs with either interpretation. A hex dump of the scratchpad, for example, gives me: e9 00 f2 0e ff ff ff ff 29 Big endian, LSB MSB e9 00 = 11101001 11110010 This gives me -14.5625 for a DS1825 and 14.5 for a 31850. For bytes 2-3: f2 0e 11110010 00001110 This gives me 14.9375 for a 31850, with a ground short fault. Values read by owfs are 0.875 for temp and 236 for thermocouple. So ... should I just read the scratchpad and do my own conversion, or can someone rewrite this? Colin On 6/29/2016 1:49 PM, Jan Kandziora wrote: > Am 29.06.2016 um 21:56 schrieb Colin Reese: >> I just pulled off the hex and noted short VDD and also ground short >> faults. These also showed up in owfs. I'm waiting on a scratchpad >> dump from onewireviewer, but how is this even possible? The device is >> both prebuilt commercially and also reads fine into a DS9490R. Is the >> data being read incorrectly into owfs? >> > My next check would be with the DS9490R and owfs. > > Kind regards > > Jan > > ------------------------------------------------------------------------------ > Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San > Francisco, CA to explore cutting-edge tech and listen to tech luminaries > present their vision of the future. This family event has something for > everyone, including kids. Get more information and register today. > http://sdm.link/attshape > _______________________________________________ > Owfs-developers mailing list > Owfs-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/owfs-developers > ------------------------------------------------------------------------------ Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San Francisco, CA to explore cutting-edge tech and listen to tech luminaries present their vision of the future. This family event has something for everyone, including kids. Get more information and register today. http://sdm.link/attshape _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
