Hi:
Steve wrote:
> Knowing only the name of the variable, the client can request the structure. For example, using the command-line pvget utility . . .
>$ pvget BL6:Det:Metadata
>BL6:Det:Metadata
>structure
> time_t timeStamp 2018-04-02T13:32:08.794 19815342
> epics:nt/NTScalar:1.0 proton_charge
> double value 0
> epics:nt/NTScalarArray:1.0 time_of_flight
> uint[] value []
> epics:nt/NTScalarArray:1.0 pixel
> uint[] value []
>. . . tells me that the variable BL6:Det:Metadata has a structure consisting of a timeStamp, a NTScalar value for proton_charge, and NTScalarArrays for time_of_flight and pixel.
pvget dumps the structure and shows the values.
If the structure contains arrays with many elements, it might be a bit much to dump on the console.
With "pvinfo" you get just the structure layout, sans values:
$ pvinfo BL6:Det:Metadata
CHANNEL : BL6:Det:Metadata
STATE : CONNECTED
ADDRESS : ...
structure
time_t timeStamp
long secondsPastEpoch
int nanoseconds
int userTag
epics:nt/NTScalar:1.0 proton_charge
double value
epics:nt/NTScalarArray:1.0 time_of_flight
uint[] value
epics:nt/NTScalarArray:1.0 pixel
uint[] value
So pvinfo would allow you to inspect the structure, and then you use pvget to fetch the pieces of interest.
As Steve mentioned, to make sense of the structure you might need additional info.
For instance, you see that "pixel" is an array of uint. But what does that mean?
-Kay
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