Re: SubArray

[Andrew Johnson <anj@aps.anl.gov>]

Hi,

On 07/14/2015 01:36 AM, ishita bhatia wrote:
> 72 bytes data is recieved in waveform record. Now i wan't to divide it
> in 2 subArrays(36 bytes). please suggest how to do that. I have tried
> the following:
> 
> record(subArray, data1) {
>   field(SCAN, "Passive")
>   field(DTYP, "Soft Channel")
>   field(FTVL, "CHAR")
>   field(INP, "datavme.VAL")
>   field(MALM, "36")
>   field(NELM, "36")
>   field(INDX, "0")
>   field(FLNK, "vmehex1")
> }
> It gives correct output :
> data1 36 53 51 -2 -19 127 -1 50 50 50 50 50 50 50 50 50 50 50 50 50 50
> 65 50 80 -14 50 64 70 -48 50 50 50 50 50 50 50 50.
> But for second subArray of 36 bytes what should I give values of MALM,
> NELM and INDX so that i can get next 36 bytes from waveform record.

To get to the second half of the input data the subarray record needs to
fetch the full array through the input link, so you must set MALM to 72,
but you only want it to export 36 elements so you would set NELM to 36,
and you want the first output element to start half-way through your
input array, so you set INDX to 36.

This is documented at
https://wiki-ext.aps.anl.gov/epics/index.php/RRM_3-14_SubArray#Array_Parameters

- Andrew

-- 
Light thinks it travels faster than anything but it is wrong.
No matter how fast light travels, it finds the darkness has
always got there first, and is waiting for it.
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