At 10:29 AM 2/12/01 -0500, Bryan Bernesi wrote:

>On another note, sometimes when I run the ERC some of my symbols are changed
>in my schematic, i.e.
>I have a PNP transistor (2N2904 symbol labeled as a TIP125) that changes to
>a different transistor symbol (taken from ????), or a LED (a created symbol)
>that changes back to the standard LED symbol (found in miscellaneous
>devices.lib) but the LED symbol does not change in all 24 modules?!?!?!?!
>
>Can anyone tell me what I'm doing wrong, or what I have not setup properly??

Well, one thing you are doing wrong, for sure, is allowing different 
symbols to have the same name. Avoid this like the plague. Sometimes the 
plague walks in the door, however.

If there were no schematic libraries enabled, it would also be impossible 
for parts to be accidentally updated. I'm not clear on why Mr. Bernesi has 
seen the exact behavior he reports, but the inner workings of the 
libraries/cache/and schematics is beyond my capacity to remember, that is, 
to remember in every detail. Perhaps someone will write a dissertation on 
the subject. There have been various fixes to cache problems in various 
service packs, so I'm not clear on what is the latest scoop on this. I take 
some pains to avoid duplicate symbol names, so I don't see the problem 
reported except perhaps on the occasion when someone else sends me a 
schematic with non-standard symbols.

Don't edit the supplied libraries and leave the names the same! In fact, 
don't edit the supplied libraries at all. You might lose your work next 
time you do an install or reinstall. Instead, make separate custom 
libraries and make the names unique. I like to make resistors with short 
pins, but I'm not going to call them RES! Instead, I've used R, which is 
faster to type anyway....

When an outside schematic, one which contains symbols which do not obey the 
naming rule I've given, which is not uncommon for libraries coming from 
someone else, there being little way to avoid it, it would not be a bad 
idea to load the schematic into a virgin schematic sheet. To be absolutely 
sure that nothing is hanging around in a cache in memory, unload all 
libraries from the schematic editor (use a blank new schematic file if 
necessary to load the schematic editor), exit Client, and restart. Then 
import the subject schematic. Make a schematic library from it. If any 
parts have names that seem likely to be used elsewhere, rename them in the 
library, then globally edit the symbols in the schematic to the new names.

Not a bad idea to have a list at hand of all the names in, at least, the 
supplied Miscellaneous Devices library....

We have suggested that the full name of a symbol include name of the 
library from which it came, including an individual symbol revision date, 
and possibly other information as well. This would cause all symbols to be 
unique unless they actually came from the same library, thus the end, for 
good, of this problem. Update from Library, however, would assume that all 
symbols with the same name (but likely different library sources or dates) 
were equivalent. It might be good to have some reporting tools to go along 
with this....

Abd ul-Rahman Lomax
LOMAX DESIGN ASSOCIATES
PCB design, consulting, and training
Protel EDA brokering (resale) services
Sonoma, California, USA
(707) 939-7021, efax (419) 730-4777
[EMAIL PROTECTED]
[EMAIL PROTECTED]




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