On 27/06/16 23:39, Jan Kandziora wrote: > Am 27.06.2016 um 18:47 schrieb samuix: >> Hi, >> with the help of digitemp_DS9097U we found following: >> In the module ow_ds9097u.c is a parameter missing, we modified a line and it >> seems to work..... >> we patched the module locally: ow_ds9097u.c row:594 : >> // default PDSRC = 1.37Vus >> RETURN_BAD_IF_BAD(DS2480_configuration_write(PARMSEL_SLEW, >> PARMSET_Slew1p37Vus, >> in)) ; >> The value (PDSRC=1.37V/µs) is mentioned in the specification >> :http://pdfserv.maximintegrated.com/en/an/AN192.pdf >> <https://deref-gmx.net/mail/client/dereferrer/?redirectUrl=http%3A%2F%2Fpdfserv.maximintegrated.com%2Fen%2Fan%2FAN192.pdf> >> after make the owserver found the sensors :-) >> > Ah, nice. That explains why it works for me. I have a very short bus, > only a single DS18S20 on a short stub. > > If you have a long cable attached, setting a lower slew rate may be > needed. See the DS2840B datasheet, page 15. > For what its worth: I have a DS2480B with a couple of hundred meters of cable on a spool (test bench) and a bunch of sensors at the end, it's working perfectly fine with stock OWFS. So there might be other electrical characteristics to take into account than just length (the usual ones: star network, bad couplings etc). So while this is probably something worth looking into, I'm just saying it *can* work with long cables :)
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