Re: add fields to an existing record

[Wang Xiaoqiang via Tech-talk <tech-talk at aps.anl.gov>]

Hi Mark,

Every ROI has a description field, e.g. R0NM.
https://epics-modules.github.io/mca/mcaRecord.html#Region-Of-Interest_Fields

It is of string type, normally used to indicate element absorption edges.
I wonder if you can append the ophyd information to it. e.g. “FeK [hinted]"

Best
Xiaoqiang

> On 12 Jun 2023, at 18:25, Wolfman, Mark via Tech-talk <tech-talk at aps.anl.gov> wrote:
> 
> Hi, tech-talkers.
> 
> Apologies in advance if parts of this don't make sense, I'm not that familiar with EPICS yet.
> 
> I'm hoping to add a new region-of-interest field [1] to the MCA records used in an existing IOC for our DXP fluorescence detector. 
> 
> Similar to the other ROI fields, I'd like to have ``20bmxmap4b:mca1.R0BH``.
> 
> This will be a 'bi' field that doesn't do anything in the IOC, but is used by bluesky/ophyd during staging to determine whether the specific ROI is hinted in bluesky (hence BH for "bluesky hint") [2] and is included in the calculations for summing ROI's across elements. I've added extra records to an IOC before, and so I tried adding this as a record but EPICS complained because my record name included a '.' character.
> 
> One solution is to add a record like "20bmxmap4b:mca1_R0BH", but this makes the Ophyd part more complicated since the Ophyd MCA support expects the ROI to have a ``.Rn`` prefix and then tries to append the ``BH`` on the end[3]. Adding a record like ``mca1_R0BH`` means I have to re-write the MCA support in ophyd so I'd prefer to use the ``mca1.RnBH`` PVs if I can.
> 
> The full IOC is available on gitlab, though it's presently a work in progress.
> 
> Looking forward to hearing any ideas on how to make this work.
> 
> Thanks,
> Mark
> 
> [1] https://epics-modules.github.io/mca/mcaRecord.html#Region-Of-Interest_Fields
> [2] https://blueskyproject.io/ophyd/user_v1/reference/signals.html#kind
> [3] https://github.com/bluesky/ophyd/blob/0802c77ec973b0ba9f8554d3bcf3a3001def7f66/ophyd/mca.py#L14
> [4] https://git.aps.anl.gov/20BM/20bmdxp/-/tree/main/