Re: Using CALC value to set NELM in subArray

["Wang, Andrew via Tech-talk" <tech-talk at aps.anl.gov>]

Hi Andrew,

Sorry for the delay. I'll send you an example of this issue sometime this week.

Thanks,

Andy

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From: Johnson, Andrew N. <anj at anl.gov>
Sent: Thursday, July 1, 2021 8:31 AM
To: Wang, Andrew <wang126 at llnl.gov>
Cc: EPICS tech-talk <tech-talk at aps.anl.gov>
Subject: Re: Using CALC value to set NELM in subArray

 

Hi Andy,

On Jun 30, 2021, at 9:01 PM, Wang, Andrew via Tech-talk <tech-talk at aps.anl.gov> wrote:

I want to use a calc record to determine what I want my NELM in a subArray record to be. I keep getting an error saying that there are no digits to convert. I feel like the problem is because the NELM field is ULONG, while the VAL field of the calc record is a DOUBLE. Don’t think it is possible to “cast” the DOUBLE to a ULONG in the calc record, unless I am wrong. Is there a way around this or is the best approach to use an aSub record?

The VAL field of a calc record holds a double, so even if you could cast the value in the _expression_ it would still be represented as a double result after the calculation was complete.

How are you copying your calc.VAL field value to the subArray.NELM field? I suspect that’s where your problem may be, are you trying to use NELM as a link? That would generate the “no digits to convert” error because NELM is a DBF_ULONG field so you can only set it to an integer numeric value in your .db file. Only DBF_LINK fields can point to other PVs. To copy the calc result into it I would use a calcout record and point its OUT link (which is a DBF_OUTLINKfield ) to the NELM field so its value will be copied.

If I’ve misunderstood what you’re doing, please post your .db file and the exact error message you’re getting; explicit examples are always much easier to debug than descriptions.

HTH,

- Andrew

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