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<== Date ==> <== Thread ==>

Subject: Re: Spurious "Channel write request failed" messages
From: Andrew Johnson <anj@aps.anl.gov>
To: <tech-talk@aps.anl.gov>
Date: Mon, 25 Sep 2017 12:08:54 -0500
On 09/23/2017 06:15 AM, Ralph Lange wrote:
> Alas, there's no bug in the issue tracker for it, and it is not
> mentioned on the "Known Issues" page. We should probably add the latter
> at least.

Patch file created and linked from the Known Problems page for 3.16.1 at
  http://www.aps.anl.gov/epics/base/R3-16/1-docs/KnownProblems.html

- Andrew

> On Sat, Sep 23, 2017 at 11:47 AM, Michael Ritzert
> <michael.ritzert@ziti.uni-heidelberg.de
> <mailto:michael.ritzert@ziti.uni-heidelberg.de>> wrote:
> 
>     Hi all,
> 
>     since upgrading from 3.14 to 3.16.1, I see the following messages on
>     the console of an IOC:
>     DB CA Link Exception: channel "dest1"
>     DB CA Link Exception:  native  T=DBR_DOUBLE, request T=DBR_DOUBLE,
>     native N=1, request N=1,  access rights {RW}
>     DB CA Link Exception: "Channel write request failed", context "dest1"
> 
>     This is from a dfanout record that simply pushes a value to another IOC.
> 
>     However, the write succeeds.
> 
>     It's totally reproducible with these two DBs run in softIOCs:
> 
>     sender.db:
>     record(calc, "count") {
>             field(SCAN, "1 second")
>             field(VAL, "0")
>             field(PINI, "YES")
>             field(INPA, "count")
>             field(CALC, "A+1")
>     }
> 
>     record(dfanout, "send1") {
>             field(DOL,  "count CPP")
>             field(OMSL, "closed_loop")
>             field(OUTA, "dest1")
>     }
> 
>     record(dfanout, "send2") {
>             field(OMSL, "supervisory")
>             field(OUTA, "dest2")
>     }
> 
>     receiver.db:
>     record(ao, "dest1") {
>     }
> 
>     record(ao, "dest2") {
>     }
> 
>     There's one messages every second about dest1, and one on every
>     write to send2.
> 
>     Cheers,
>     Michael
>     --
>     Dr. Michael Ritzert                     Tel: +49 621 181 2883
>     <tel:%2B49%20621%20181%202883>
>     Schaltungstechnik und Simulation        Fax: +49 621 181 2734
>     <tel:%2B49%20621%20181%202734>
>     Technische Informatik, Uni Heidelberg 
>      michael.ritzert@ziti.uni-heidelberg.de
>     <mailto:michael.ritzert@ziti.uni-heidelberg.de>
>     68131 Mannheim, Germany               
>      http://sus.ziti.uni-heidelberg.de <http://sus.ziti.uni-heidelberg.de>
> 
> 

-- 
Arguing for surveillance because you have nothing to hide is no
different than making the claim, "I don't care about freedom of
speech because I have nothing to say." -- Edward Snowdon

References:
Spurious "Channel write request failed" messages Michael Ritzert
Re: Spurious "Channel write request failed" messages Ralph Lange

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