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
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.
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.-
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