Experimental Physics and
Industrial Control System

Michael Davidsaver via Tech-talk <tech-talk at aps.anl.gov> · Fri, 23 Apr 2021 15:42:37 -0700

On 4/23/21 2:48 PM, Pierrick M Hanlet via Tech-talk wrote:
> Hi Andrew,
> I get:
> epics> dbpvar PIP2IT-HPRF-SSR1-SSA2-00:OFP:ControlPVs 4
> PVA links in record named 'PIP2IT-HPRF-SSR1-SSA2-00:OFP:ControlPVs'
> 
>                      P:S12OFP conn=F 0 disconnects, 0 type changes, 
> provider 'pva'
>    0/1 channels connected used by 1 links

"conn=F" is the key point.  The link isn't connecting to the target PV "P:S12OFP".
Does a "pvget P:S12OFP" from the IOC host succeed?  To understand why we need to
look at the PVA client settings used by the IOC ($EPICS_PVA_*).

Also, it would be good if status==LINK_ALARM were getting set in this situation, but it isn't.
Probably because I'm not processing initially disconnected links.  Something to look into...

>>>      Warning: "Channel write request failed"

Are you loading any Access Security configuration?
Can we see the init script or softIocPVA arguments used?

> Cheers,
> Pierrick
> 
> 
> 
> On 4/23/21 4:31 PM, Johnson, Andrew N. wrote:
>> Hi Pierrick,
>>
>> Does the iocsh ‘dbpvar’ command tell you anything interesting/useful about the state of the pva link? You can give it a record name, or “*”, and an integer level for more and more detail about the link(s).
>>
>> - Andrew
>>
>> On Apr 23, 2021, at 4:10 PM, Pierrick M Hanlet via Tech-talk <tech-talk at aps.anl.gov> wrote:
>>> Hi all,
>>> I'm running v7.0.3.1 on an SL7.8 machine.  I'm using structured data, with a sub-structure
>>> called Control.  I know that the structure/sub-structure is being properly set by testing it
>>> with a pvmonitor:
>>> pvmonitor -r Control P:S12OFP
>>> which yields:
>>> P:S12OFP structure
>>>      structure Control
>>>          time_t timeStamp <undefined>
>>>              long secondsPastEpoch 0
>>>              int nanoseconds 0
>>>              int userTag 0
>>>          short value 8
>>>
>>> I want this Control value to populate another record which has the form:
>>> record(longin,"PIP2IT-HPRF-SSR1-SSA2-00:OFP:ControlPVs") {
>>>      field(DESC,"Trigger Control PVs from acnet device")
>>>      field(SCAN,"Passive")
>>>      field(INP,{pva:{pv:"P:S12OFP",
>>>              field:"Control.value",
>>>              proc:"CP"}})
>>>      field(FLNK,"PIP2IT-HPRF-SSR1-SSA2-00:OFP:SetPVs.PROC")
>>> }
>>>
>>> However, this value doesn't change despite its input value changing.  Furthermore,
>>> if I attempt to change it's value with:
>>> caput PIP2IT-HPRF-SSR1-SSA2-00:OFP:ControlPVs
>>> then get the error:
>>> Old : PIP2IT-HPRF-SSR1-SSA2-00:OFP:ControlPVs 0
>>> CA.Client.Exception...............................................
>>>      Warning: "Channel write request failed"
>>>      Context: "op=1, channel=PIP2IT-HPRF-SSR1-SSA2-00:OFP:ControlPVs, type=DBR_STRING, count=1, ctx="PIP2IT-HPRF-SSR1-SSA2-00:OFP:ControlPVs""
>>>      Source File: ../oldChannelNotify.cpp line 160
>>> New : PIP2IT-HPRF-SSR1-SSA2-00:OFP:ControlPVs 0
>>>      Current Time: Fri Apr 23 2021 15:45:03.687389769
>>>
>>> Thank you,
>>> Pierrick
>>>
>>> -- 
>>> Pierrick Hanlet
>>> Fermi National Accelerator
>>> Accelerator Front End Controls
>>> +1-630-840-5555 -- lab
>>> +1-312-687-4980 -- mobile
>>>
>>> "Whether you think you can or think you can't, you're right" -- Henry Ford
>>>
> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System