On 3/21/19 2:10 PM, Shen, Guobao wrote:
> The union is what we are using for our fast DAQ data from FPGA.
> Our engineers designed the structure that format, and it has similar structure with AD image.
> We do not use a union containing a structure, which might complicate the system.
>
> In this case, you mean what I got is what I should expect. Right?
Yes. What you see is what I would expect.
This will work.
> $ pvget -r value Test:Data
This is not meaningful.
> $ pvget -r value.data1 Test:Data
I will grant you that 'Status [type=FATAL, message=std::bad_alloc]'
is not the error I would have expected to see from the pvRequest string parser.
> On 3/21/19, 1:20 PM, "Michael Davidsaver" <[email protected]> wrote:
>
> On 3/21/19 8:43 AM, Shen, Guobao via Core-talk wrote:
> > Hi Core member,
> >
> > Does anyone have experienced to read sub field of a Union structure?
>
> What you are showing looks like a discriminating/tagged union.
> This is quite different to having a union containing a structure,
> which is maybe what you expect?
>
>
> > For example, I have a record:
> >
> > $ pvinfo Test:Data
> >
> > …
> >
> > structure
> >
> > uint ArrayId
> >
> > double[] Time
> >
> > union value
> >
> > float[] data1
> >
> > double[] data2
> >
> >
> >
> > If I use
> >
> > $ pvget -r value Test:Data
> >
> > Test:Data
> >
> > structure
> >
> > union value
> >
> > float[] [-0.034794,-0.0417011, …]
> >
> >
> >
> > But if I do it with:
> >
> > $ pvget -r value.data1 Test:Data
> >
> >
> >
> > I got an error on my client like
> >
> > [Test: Data] failed to create channel get: Status [type=FATAL, message=std::bad_alloc]
> >
> >
> >
> > Is that a right way to use it for union?
> >
> >
> >
> > Thanks,
> >
> > Guobao
> >
>
>
>
- Replies:
- Re: Get sub field of Union Benjamin Franksen via Core-talk
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- Get sub field of Union Shen, Guobao via Core-talk
- Re: Get sub field of Union Michael Davidsaver via Core-talk
- Re: Get sub field of Union Shen, Guobao via Core-talk
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