RE: [plcs-dex] Questions regarding Next_assembly_usage

[Peter Bergström <peter.bergstrom@eurostep.com>]

Still it all boils down to an parent part (the circuit board) and a child part (the transistor), and the location.

In PDM schema this is done using ordinary part assembly structures, where multiple next_assembly_usage are used between them to separate the locations and make the usage for each location visible.

In PLCS you can do that, indicating the location in the location_indicator attribute (which is not in PDM schema), as shown below:

Part circuit board
    |
  N_a_u 'R1'
    |
Part transistor


In fact, you can also use the entity Attachment_slot for the location, if you like:

Part circuit board
    |
  N_a_u
    |
Attachment_slot R1
    |
  N_a_u
    |
Part transistor



But you can also define a whatever_breakdown (I buy your reasons for functional), and use several combinations of elements to represent this:

Cuircuit board element -realized_as-> part circuit board
         |
   Element_usage
         |
Transistor location R1 element -realized_as-> part transistor


Or

Cuircuit board element -realized_as-> part circuit board
         |
   Element_usage
         |
Location R1 element 
         |
   Element_usage
         |
Transistor element -realized_as-> part transistor   


Or

Cuircuit board physical element -realized_as-> part circuit board
         |
   Element_usage
         |
Location R1 zone element -in_zone-> part transistor



Using breakdowns, you get a second abstraction level to the data, which can be very useful when you want to talk about the logical things as separate from the parts.

I'm not saying that any of the above is more correct than the other, or even that it should be done in any of the ways above - in fact I do not know which method to use, and I have a feeling that it is partly business dependent.

I just know that if you want to be able to individually identify a location in the design (where you design with parts) and you want to identify different torch values or whatever for the different positions, the PDM schema way is also useful.

And I have a distinct feeling that time is not mature enough to settle this in favor of breakdowns for all business areas just yet.

I might be incorrect, and that's why I need input from you people.
(Dave has not convinced me yet...)


Peter



-----Original Message-----
From: David Price [mailto:david.price@eurostep.com] 
Sent: den 31 mars 2007 13:38
To: plcs-dex@lists.oasis-open.org
Cc: Peter Bergström
Subject: Re: [plcs-dex] Questions regarding Next_assembly_usage

Hmmm....  we may be talking about different things. R1 on a circuit board, as 
I understand it, is a logical thing - not a physical thing. That R1 
identifier was created in the ee logic design system long before things got 
physical. At least that's my recollection, although this was many years ago.

Either way, left from wheel or R1 are not a parts in an assembly. "Part" has a 
special meaning - or at least did in IBM and similar mfg orgs - of being the 
smallest physical component in a design. Of course, some of IBM's Parts were 
other people's assemblies but in no case was Part used to define a 
logical/functional item.

Hope this is helping,
DP

On Saturday 31 March 2007 09:43, Peter Bergström wrote:
> In a breakdown (although for this particular example I should use a
> physical breakdown, not a functional) you would instantiate different
> breakdown_elements for the different locations, but I don't think it is the
> same as to say that it's the left or right wheel in an assembly of a car,
> or that an electronic component should be place in a specific place (named
> location) on a circuit board. In the latter we are actually talking about
> parts in a parts assembly, where we have a requirement for how or where the
> assembly is done.
>
> You could do the same with a breakdown structure, but there you are not
> really talking about designed parts directly - you would have to realize
> the breakdown elements into parts to achieve the same.
>
> In some cases that is desired, e.g. early design and in-support, but for
> the detailed design phase it is necessary to be able to talk of the
> location of a part in context of its upper level part in a parts assembly,
> as well. At least, that is my understanding...
>
> Peter
>
>
> -----Original Message-----
> From: David Price [mailto:david.price@eurostep.com]
> Sent: den 31 mars 2007 01:50
> To: plcs-dex@lists.oasis-open.org
> Subject: Re: [plcs-dex] Questions regarding Next_assembly_usage
>
> On Friday 30 March 2007 19:48, Peter Bergström wrote:
> > Regarding location_indicator:
> > If this is just a hangover, what in PLCS is replacing it?
>
> I assumed a functional breakdowns covered this requirement. Is that wrong?
>
> Cheers,
> David
>
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