Reading and writing older versions

We've got 2005 and may go to 2006 if the dust settles. Some of our vendors
use 2004.

I got an email from Solidworks for DWGgateway, which will let me
(supposedly) open and edit any DWG file using any version of AutoCAD. Is
there a similar way to do this in Solidworks?

Thanks,

John

 

Nope. SW is not backwards compatible across major versions (it is
between service packs within a major release).
This is a major item of discussion that people want.

You can save back from later versions of SW to earlier ones by saving
as a Parasolid. You will get a "dumb" solid when you open up in the
old version, without history or parametrics.

The best you can do is save a part in Parasolid and open in a previous
version of SW and use FeatureWorks to try and recognize some geometry
and pull out some history. This only works on simple geometry though.

This makes playing in the same sandbox with suppliers/customers with
different versions a little tricky.
~Alex

 

It would be downright silly to ask for.
The ONLY way such could work would be no changes to
the part database structure to support new features of to fix
old bugs. Static.
Even migrating old part database structures forwards is
a wonder at times but must be done in some way.
Never expect more than one release level on that ...

 

Well,

I know it's not exactly the same thing, but my Word XP will save as other
versions back to '95 or even DOS. It will occassionally warn you that some
features may be lost, but it at least it tries.

It is interesting that Solidworks purports to do the same thing for Autocad
files. I agree that the SW files may be more complex, but that doesn't sound
impossible. Imagine what a company could do working with it's own files, not
someone elses'.

John

 

John,

The biggest difference here (and it's huge) is that if your missing
something in a word doc, or even an Autocad 2D drawing, the system can still
usually read, and use, what's there.

Solid modeling systems in general are much different. The mathematics of the
model "must" resolve to form valid topology within the accuracy of the
system. With SW that's at least 10e-8 meters, and this is just the topology,
faces, intersections, and vertices.

Add to that the construction database with it's dimensions, geometric
relations, equations, and all the rest, and you have an exremely complex
data object.

If the system can't resolve it, (missing, corrupt, incomplete, or wrongly
defined elements) alot of things can happen. All of them bad by the way. At
best you could get a "corrupt file" warning, and it just won't open. At
worse, it could freeze or crash the application. Or even crash the entire
system to a blue screen.

These are just some of the requirements for a model within the software
version in which it was created. Now you want to save this binary hairball
to an earlier binary hairball that doesn't support some of the critical
elements that comprise it's construction in the newer version.

I don't doubt that if SW were to throw enough money and development time at
it, they could make something that worked in "some" cases. The problem is,
they would take so much heat for the times it didn't work, that they'd just
prefer not to open this can of worms in the first place. Can't say as I
blame them either


Regards

Mark

 

Although a SW part file looks really really big sometimes, the actual
information takes up very little space. As it is your vendors that use
SW are you sending them parts to make or are they sending you their
parts? I would assume you are sending them stuff. If they send you
parts it is trivial usually to import them with the feature tree. If
you have to send them parts that can be done with parasolids which has
the advantage of being fixed/static geometry so that any changes from
what you intended would be easy to document. Sending them drawings
would be a bit of a problem which is ironic because drawings are
probably the one SW document that could be made backward compatible
because it is after all 2D geometry. Even if you send them a drawing in
2006 they can still download the viewer to have a look.

 

John,

I agree that it should be very easy to do some prismatic parts. Many would
only require transposing the instructions. In fact, all you would need are
the instructions in some cases. SW 95 didn't store any hard geometry in the
part file. The files were really small too. Took longer to load though.

The place you would run into problems with prismatic parts are things like
feature patterns. For instance SW2004 can't do true 3D patterns along a 3D
curve. 2005 & 2006 can. How do you account for this ??

"Making unsupported features dumb solids" kind of rolls off the tounge real
easy. Not so easy when you really think about it. If the base features of a
shape are two or three complex lofts or sweeps, shelled with a ton of bosses
ribs and other internal stuff, most of it will be orphaned if the lofts are
dumb. Whether they're left dangling or broken, allot of work will be
necessary on the recieving end to fix it up. How many time can a model make
the round trip between the newer/older-older/newer cycle before the only
real features left are a couple of holes ??

I really don't think it can be implemented in a way that has any real value


Regards

Mark

 

Migrating a part database forward ONE version level must
include quite a few "IF" (conditional) statements/instructions
followed by GTOs.
You can only go the other way using conditional COMEFROM
statements.

Consider: 1+4 =5
2+3=5

You have 5.
Now, migrating it backwards ...... should it
be 276-271? And it's much worse than that, actually.

(Remember this the next time poor clueless starts yammering
about "reverse posts" or building solids/geometry from MDI edited
G-code and suchlike <G>)

And new features are added, not subtracted.

 

I haven't post anything in this group for a while.... But I love when
this subject comes up. It's so much fun reading
everyone's ignorant responses. The irony here is, I know I'm sounding
ignorant myself but I can't hold back from this
subject without sounding impolite or sarcastic....

Yes guys, it's true. Solidworks and other companies have created a
giant money generating conspiracy. Together,
they make you believe they can just quickly generate some simple code
that allows you to save to a previous version.
As a matter of fact, it would be so easy to do they would rather just
make you pay for upgrading to the newer software.
(Am I sounding sarcastic here... I hope so!)

Apparently nobody understands natural order, programming, or even logic
for that matter. What makes people think Solidworks
can just have 1 guy hand over the code to make backwards compatibility
happen? The truth is that it would be way too complex and big of a
problem from a programming/database standpoint to be able just to be
readily available at the same cost the user. I have to believe this
would cost a fortune in development only to meet it's demise when
people won't pay $$$ for the ability to use it. THIS DOES NOT COME FOR
FREE PEOPLE!

When you think about all the problems and money it would take to
accomplish such a task.... doesn't it just make sense to pay for the
upgrade? Apparently some people just don't understand this.

By the way.... I keep putting my DVD movie into my CD player I bought
12 years ago and it doesn't work.
Why can't they just make the DVD backwards compatible???? GIVE ME A
BREAK!!

Sorry for sounding rude... I meant to sound realistic.
Don Van Zile

 

John,

The technical problems I pointed out are very real. Whether or not the CAD
companies are taking advantage of it,,,,well, who knows, probably

I've been doing 3D CAD since long before Solidworks. Too my knowledge, no
parametric system has ever had backward compatibility. If you take the time
to "really" understand the way they work, the potential problems become
obvious.

Mark

 

If someone chose to do it, it is certainly doable. Barenboym had
developed something that worked on limited feature types, but it worked.

Look at what SW can do with native ProE files. If it can be done from
ProE to SW it can certainly be done much more easily from SW2005 to
SW2001+. Any features that don't have an equivalent in an old version
are either brought forward as a dumb solid or left out, same as the ProE
conversion. Something is better than noting.

The question then becomes "why". It probably wouldn't be a big money
maker, because the people who are hanging out on old versions are
probably doing it to avoid spending money in the first place.

I honestly don't believe it is a technical issue. It's a business
issue.

Matt

 

Matt,

You've correctly pointed out that there would be very real limits.
Solidworks doesn't really do much with Pro files based on complex shapes.
Your choices are single body, or a mess. The mess isn't worth trying to
clean up. So much for dumb or incomplete features. It does work on prismatic
parts "provided" the person doing the modeling (in pro) used straight
forward construction methods. I've seen Pro models where the guy used
variable section sweeps to construct countersinks.

Something is better than nothing is only "your" perspective. There will be
legions of users who will piss and moan because of the limitations. They'll
complain loudly about another half baked Solidworks feature. It's human
nature, not worth the hassle.


Mark

 

Not really.

Perfect example. "Limited feature types".
Let me guess: data was lost. And those "limited types"
were not much changed from version to version.

You could use DXF or IGES too, right?

But you just said that it did not.

But that's not what's being requested.

There are other reasons too.

Consider it a non-reversible trap door function.
Or just use LOTS of COMEFROM statements in the
programming ...

 

"Your choices are single body, . . ."

Here's my take on this:

1) It's parasolids in there somewhere.

2) If we can take in pro files as a dumb solid, at least give us the
option to take in a "frozen" parasolid from future SolidWorks versions.
Predicated on compatible parasolid versions maybe (not something I can
really see).

3) Given a drawing, at least let the editor open a future version in
view mode, or perhaps even a variant of "detached drawings". I know
the viewer is available, but that's not my point.

Full backwards compatibility would be a total CF.

Today I had a model from my vendor in 2005 and could not open it in
2004. OK that makes sense, BUT it would be nice if I could open the
model as a "frozen" solid, basically having the editor read the
internal parasolid data for me - basically nullifying the need for a
dumb solid as the communication vehicle between solidworks versons. I
think that this could even extend into an assembly being able to take
in future data as frozen.

I think that being able to open a file as frozen and use the geometry
as needed is not too much to ask for. Full parametric compatibility is
probably a very tall order and strewn with roadblocks.

I hate to even mention this (surely opening the floodgates of idiocy)
but what about having a limited direct manipulation mode when opening a
future file in an older version?

Later,

SMA

 

ParaSolid also has different revision levels,
none backwards-compatible AFAIK.
That will just add to your problems <G>.

 

When they wrote 2004 do you suppose that they already
had released 2005? Or that everyone else had done their
part too (all sorts of things get linked up for the release).

 

And then you have NX which can take a totally dumb file and treat
features in it as if they were parametric in origin, dragging,
retrimming, etc. 90% of users use a very simple pallette of features.
Those features haven't changed much over time. And from what I
understand the code to make them in the older versions remains in the
newer versions to enable backward compatibility.

 

Maybe we could all write Autodesk and have them make a "SLDPRTransfer"
program, and then we as SolidWorks owners could get it for free off there
website!

In all seriousness,

Regressing back to a previous version would be difficult. To create the
newest versions features, to the previous one would be more and more
complicated as you would go back to a version, 2003 more complicated than
2004, than 2005, etc. Because of course new features and model methods are
added to each new version. Thus slowing down each new version.. just
kidding ;-) SolidWorks out paces "Moore's Law"!

My vote would be to convert it as good as can be done with the features of
that version, then just fill in the gaps with a dumb solid. We as users
could then go back and make new sketches/features using our skills...
something that is very hard for a computer to do. Much like interactive
"Raster to Vector" conversion. And also (I hate to say it) kind of like
FeatureWorks. But unlike FeatureWorks, the SolidWorks Programmers who know
the formats could do this conversion much better and leave the unconverted
"dumb" solids for us to deal with and model, we humans are good at that
part.

Again, at least it is better than nothing... This is probably the most
wanted program function of all time for SolidWorks.

Aron

 

Yeah,

My view is fairly simplistic and certainly unenlightened as to the
intricicaies of the problem. I have no clue as to how often the guts
of the ting is upgraded and perhaps this is why there is no backwards
compatability.

But if SolidWorks can read a Pro-E file in a dumb format, reading their
own stuff _should_ be possible, especially in dumb format. I think
that regardless of future intent, they should be able to read in their
own future format (stupidly I mean). I think that it is pure nonsense
to think that they have NO control over how their data is structured
from one release to the next.

Give me something (for the record, I do not expect anything to ever
happen realtive to inter version compatability).

Later,

SMA

 

Hi TOP-

That's what I was thinking. Something is wrong and maybe this is too
big a leap. To have history trees and direct co-operate.

But damn what a wish list item.

I expect them (or someone) to come up with a solution to make this sort
of big picture stuff happen. I hope that they have a think tank and
would not be shocked if there is some sort of body in the company that
thinks about this stuff all day. Sort of like an advanced development
function. I know that we will likely wait a decade for a major change
and perhaps SolidWorks will not be capable of being the "lusted after"
CAD of the future. They may just rest on their laurels and get comfy
maintaining the status quo.

In any case, the future belongs to the people who can innovate. In CAD
and any other business.

Later,

SMA