Experimental Physics and
Industrial Control System
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| <== Date ==> | <== Thread ==> |
|---|
| Subject: | Re: AsynPortDriver separate thread causes Segmentation fault with "dbGetLinkValue" error message |
| From: | Abdalla Ahmad via Tech-talk <tech-talk at aps.anl.gov> |
| To: | Michael Davidsaver <mdavidsaver at gmail.com>, Mark Rivers <rivers at cars.uchicago.edu>, "tech-talk at aps.anl.gov" <tech-talk at aps.anl.gov> |
| Date: | Thu, 5 Nov 2020 15:46:14 +0000 |
|
Hi all.
Buffer size is 48 because the device sends waveform data in lines so I read each line separately by reading 48 bytes, If I request ADC 200 for example I receive 200 lines where each line is 48 bytes. I even did a test where I used a buffer size of 1M to receive
the full 20000 lines and still got the same error.
Regarding EPICS waveforms, what I meant is variable length from the client side; For example I set a buffer size in a PV and based on that PV value I read a specific length so that a plotter for example reads data with that specific length only. Does NORD achieve
this? If yes, how does asyn access individual record's fields?.
Best Regards,
Abdalla.
From: Michael Davidsaver <mdavidsaver at gmail.com>
Sent: Tuesday, November 3, 2020 7:18 PM To: Mark Rivers <rivers at cars.uchicago.edu>; Abdalla Ahmad <Abdalla.Ahmad at sesame.org.jo>; tech-talk at aps.anl.gov <tech-talk at aps.anl.gov> Subject: Re: AsynPortDriver separate thread causes Segmentation fault with "dbGetLinkValue" error message On 11/3/20 8:49 AM, Mark Rivers via Tech-talk wrote:
> - I don’t think EPICS supports variable length waveform records. You need to create the waveform record in dbLoadRecords with a size that is the largest you plan to use. That is what areaDetector does with NDPluginStdArrays. To clarify, waveform records have a _maximum_ size which is fixed on initialization (eg. NELM). Actually size (NORD) has long been changeable at runtime in the range [0, NELM]. Some caveats about NORD==0 apply wrt. CA specifically (works fine with PVA). |
- Replies:
- Re: AsynPortDriver separate thread causes Segmentation fault with "dbGetLinkValue" error message Mark Rivers via Tech-talk
- References:
- AsynPortDriver separate thread causes Segmentation fault with "dbGetLinkValue" error message Abdalla Ahmad via Tech-talk
- RE: AsynPortDriver separate thread causes Segmentation fault with "dbGetLinkValue" error message Mark Rivers via Tech-talk
- Re: AsynPortDriver separate thread causes Segmentation fault with "dbGetLinkValue" error message Michael Davidsaver via Tech-talk
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