Re: Naming bits in an mbbiDirect record

[Ralph Lange via Tech-talk <tech-talk at aps.anl.gov>]

My conceptual concern is the following:

On Mon, 7 Sept 2026 at 12:46, André Favoto <andrefavotto at outlook.com> wrote:

...

That on pvget would look like:

pvget  myStatusBits.B1

...

For a bit signal (e.g., the power status bit of a device), that name is bad.

Once you have to change the implementation (wiring or PLC / software change), your PV name must change - there's no way around that.

This will break all OPI panels that address the single bit signal.

If you want to include the signal in an archiver request, how would the archiver know that myStatusBits.B1 used to be myOtherBits.B5 before a specific date? It doesn't.

Changing PV names is a nightmare for long term support and maintenance of a system.

A power status bit should have a name that carries exactly that information - power status bit. (Mangled through your naming convention, of course.)

If you need to change the INP link to point to a different status word/bit- it is an internal change that clients and archiver don't see - and IMHO shouldn't see.

Your approach of avoiding bi records makes low-level implementation details part of the API, which is wrong.

This is a general argument for using the common architecture with separate bi records and not directly related to description strings.

Cheers,
~Ralph