Hi Robert, On 01/03/2012 04:40 PM, Robert Conway wrote:
> Thanks for the advice, its good to get my network re-established again. > After checking connections etc I went through my read script and started to > comment out every device in turn. > > It turns out that the CRC16 errors are caused by "$OWWRITE > simultaneous/voltage 1" > > Before I take a reading I execute the following in my bash script > > OWWRITE="/opt/owfs/bin/owwrite -s 3001" > > ### Force Simultaneous 1wire conversion ### > $OWWRITE simultaneous/voltage 1 > $OWWRITE simultaneous/temperature 1 > > Now "sim/voltage" was in there because I had used a DS2450 quad AD however > it is NOT currently connected to my network. > > OUTCOME: > "$OWWRITE simultaneous/voltage 1" causes 1xCRC16_tries and also 1x > CRC16_error both increment together. I have NOT tried connecting my > DS2450 to the network yet to see if this changes. Maybe the server expects > a return message on the bus ??????? > > "$OWWRITE simultaneous/temperature 1" I assume this is working on the bus > however this command does NOT increment CRC16_tries. I find it unusual that > sim/voltage uses CRC16 try and sim/temp does not increment CRC16's ow_2450.c shows a few CRC16 bus transactions and ow_1820.c just shows one CRC8 transaction. This explains why you do not see CRC16 tries when accessing the DS18x20s. If you do not have DS2450s in your network then there is one thing that I don't understand: why do you have 30% error rate on the CRC16s? That seems to imply that some CRC16s are good. But who is generating/processing them? > Deleting "simultaneous/voltage 1", I only see CRC8 tries, zero CRC8 errors > and there is a very small amount of CRC16_tries and zero CRC16_errors now > so I am now very happy. > > QUESTION: > Is simultaneous/voltage 1 a valid command if there are no DS2450 on the bus, > or is this a bug ? Maybe I have always had this problem from the very > beginning years ago. No idea here, but it's a good question, and one I'd like to know the answer to as well. Cheers, Eloy Paris.- > > FYI just upgraded to 2.8p14 although I am sure it was the same in 2.8p9 > Rob > > > > -----Original Message----- > From: Eloy Paris [mailto:[email protected]] > Sent: Wednesday, 4 January 2012 4:54 AM > To: [email protected] > Subject: Re: [Owfs-developers] What are CRC16 errors > > Hi Robert, > > On 01/03/2012 07:32 AM, Robert Conway wrote: > > [...] > >> I have on my network >> >> 2 x Hubs (Hobby Boards) >> >> Humidity, UVI, Barometer (Hobby Boards) >> >> DS18S20,DS18S20, DS 18B20 temperatures >> >> DS2423 Counter >> >> If I look at Bus/stats/errors I see no CRC8 errors out of 217 tries, >> however am getting 30% error rate on the CRC16. Just started the >> system back up as I did an upgrade to 2.8p14 and I see 39 tries and 14 >> errors for the CRC16. >> >> What devices use CRC16 ver CRC8. ? > > Running "grep CRC *c" from within module/owlib/src/c/ should give you a a > good idea of what devices use CRCs. > > After a quick check, it seems like the DS18x20 sends a CRC8 when the > scratchpad is read, and the 2423 uses a CRC16 in some operation. > > The HobbyBoards devices (driver in ow_eeef.c) do not seem to use CRCs for > anything. > > The HobbyBoards hubs are based on the 2409, which does not seem to use CRCs. > >> What do others people get in terms of errors on their >> bus.0/statistics/errors ? > > In one bus with only 12 DS18B20s (I'd say this bus has a decent long run), I > currently see 0 errors in 111534 CRC8 tries (no CRC16 tries in this bus). > > On another bus with 2 custom, microcontroller-based devices and 2 DS18B20s, > I see 143/10276 CRC16s and 215/14004 CRC8s. This does not mean anything, > though, since those errors are caused by bugs in my firmware and not because > of physical/electrical problems with the bus. > > In your case, I think the bottom line is that since you are seeing some CRC > errors, there is likely some physical/electrical problem with your wiring or > bus. > > Cheers, > > Eloy Paris.- > ------------------------------------------------------------------------------ Ridiculously easy VDI. With Citrix VDI-in-a-Box, you don't need a complex infrastructure or vast IT resources to deliver seamless, secure access to virtual desktops. With this all-in-one solution, easily deploy virtual desktops for less than the cost of PCs and save 60% on VDI infrastructure costs. Try it free! http://p.sf.net/sfu/Citrix-VDIinabox _______________________________________________ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
