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Coinciding with the acquisition of VIA Development, Nate joined Autodesk in March of 2003 after a decade stint as an entrepreneur following a two-decade stint as a controls engineer and software applications developer at Owens-Corning. Nate is now the lead product architect for AutoCAD Electrical. He loves this stuff.
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Entry into the Grandpa world
June 30, 2006 01:57 PMby Nate HoltThis little man, Cyrus Nathan Holt, turned me into a grandpa on June 14!
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Melting Glaciers and Not Enough Hours in the Day
June 29, 2006 05:11 AMby Nate HoltIf you're like me, it seems that sometimes there just aren't enough hours in a day (especially in the weeks before an AutoCAD Electrical release). The high-priced consultants say "work smarter, not harder"... but I wonder if they really have a clue.
Is there hope? Donno, but I got to thinking that maybe, with patience, this problem will self-correct. The solution may be in melting glaciers. The water run-off might slow the earth's rotation down (and make days longer!).
The key is an immutable law, the Law of Conservation of Angular Momentum. This stuff can neither be created nor destroyed... and the earth has a fixed quantity of it.
Here's an analogy... a figure skater spinning on the ice. Her arms and hands held closely together and stretched out above her head. In this pose, her "moment of inertia" is small and the spin rate is very high. Her fixed angular momentum is the product of these two values. Now she slowly pulls her arms down, elbows go out, hands start to separate. Her moment of inertia increases. Since the angular momentum is fixed (i.e. conserved), the spinning rate has to decrease to keep a constant momentum value. She flings her arms straight out, maximizing her moment of inertia, and the spin nearly stops.
Let's say the figure skater is the planet earth and her arms and hands represent the polar ice pack at the top and bottom of the planet. Since these are pretty much on the axis of rotation, they don't contribute much to the overall moment of inertia. But, when the polar ice caps melt and the water spins out toward the mid section of the planet (like the figure skater pulling her arms down and out), this now begins to seriously contribute to an increase in the planet's moment of inertia. The earth's rotation would have to slow down to avoid breaking the conservation of angular momentum law.
So, let's try to figure out how much extra time we can get in a day if we wait around for the ice caps to melt...
One of the more dire predictions is that glacial melting will contribute about a 2.5 inch rise in sea level. If this were spread out over the whole planet (which is 30% land, 70% oceans), it would be about a 2 inch rise overall. So, we need to compare the moment of inertia of the planet earth with this water frozen at the poles (current condition) versus the new moment of inertia with the equivalent of an extra 2 inches of melted glacier water spread out over the whole planet.
Google provides some numbers for crunching. The mass of the earth is 5.98x10^24 kg, radius is 6.4x10^3 km and the weight of 2 inches of water spread out over the earth's surface calculates to be something like 7x10^16 kg. Moment of Inertia calculations for a solid sphere (full earth) and a spherical shell (the 2 inches of water) are here and work out so that the difference is about 0.00000000071 between the two scenarios (earth sphere+fozen poles versus earth sphere+2" water shell).
So, the angular velocity of the earth would have to slow down by this factor, 0.00000000071, in order to maintain its fixed angular momentum. What does this work out to? 365 days in a year x 24 hrs x 3600 seconds = 1,227,600 seconds in a year. Multiply by the slow-down factor and we end up with a year that is 0.009 seconds longer.
Is this right? Doesn't seem like much.
Guess will have to try to work smarter.
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User Struggle with Reversing Starter - WDTAGALT approach
June 26, 2006 12:56 PMby Nate HoltThis came up last week. A user was 90% there in getting his reversing starter annotation to work the way he wanted. Two parent coils, different tags, only one carries the overall BOM catalog assignment, each carries its own PINLIST assignment ("peer" PINLIST data retrieved from the one with the initial catalog assignment). The WDTAGALT attribute added to both and pointing at each other's tag value so that Surf works between the two halves of the reversing starter (i.e. a peer-to-peer relationship instead of a parent-child relationship).
A final sticking point was that he wanted the reversing coil tag to be listed in the BOM report along with the main coil's tag. This is a problem because the BOM report just shows components that carry a non-blank catalog part number assignment... all the rest are filtered out. And he can't put the same part number on both halves of the starter because the BOM report will then report double quantity.
What to do?
Possible work-around: write a small addition to the BOM report's "User Post" AutoLisp utility. Add this new user-selectable option: query the scratch database file, look for WDTAGALT assignments that match up with tags currently listed in the BOM report, and format the alternate tag into the report.
It appears to work!
If you want to experiment with this, the modified User Post AutoLisp utility and dialog DCL file are zipped here. Tested on ACE2007.
1. Back up current versions of bom.lsp and bom.dcl in your "c:\program files\autodesk\acade 2007\support\" folder.
2. Download file and unzip into the above folder, overwrite existing bom.lsp and bom.dcl
3. Set up the test by inserting a couple motor starter coils. Add a catalog part number to the first coil. Leave the 2nd coil with NO part number assignment. Use the ADD ATTRIBUTE utility to add attribute WDTAGALT to the first coil. Give this attribute a value that matches the 2nd coil's tag value (ex: first coil might be "MS100FWD", second "MS100REV"... the FWD coil gets the catalog part number assignment and the extra WDTAGALT attribute with a value of "MS100REV" on it).
4. Run the BOM report. When report displays, select "User Post" button. When sub-dialog displays there should be a new 3rd option related to "Include WDTAGALT tags". Select it. Hit OK.
5. Now check your displayed BOM report. See if the extra reversing starter coil's tag is now included in with the main tag.
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Adding unused core/conductors to Cable From/To report
June 12, 2006 03:23 AMby Nate HoltThis suggestion just came up late last week... how about an option to include unused cable conductor (cores) in the Cable From/To Report? Sounded like a good idea but the cable from/to report works off of actual wire connections pulled from the WFRM2ALL table in the project's scratch database file. This table has no clue about extra, unused cable cores/conductors that are only defined by a cable marker's catalog part number assignment. So, are we stuck?
Nope. This is where YOU can make cool things happen with a bit of custom programming. Take a look at this addition to the Cable From/To Report's "User Post" utility, modified version here. Substitute this for the existing one and now the extra data can be automatically pulled into the report.
If you want to try this out (I only tested on ACE2007), follow these instructions:
1. Get into your "c:\program files\autodesk\acade 2007\support\" folder. Back up files cablecon.lsp and cablecon.dcl.
2. Download above file and unzip into the above folder. Overwrite existing version of both files.
Now run your Cable From/To Report. When it displays in the report dialog/window, select the "User Post" button. On the next dialog, select the 2nd option. That should do it. If your cable markers carry catalog part number assignments & cable core/conductor lists on a per-part number basis, then unused entries should get pulled into the Cable From/To Report.
UPDATE: enhanced to group entries together by cable tag and to display in the core/conductor list order.
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Flipping between "Shop floor" and "Customer" tags
June 8, 2006 08:12 PMby Nate HoltHere's another user problem that came along in last 72 hours. It's a head-scratcher... they want to start their controls design using internally generated "shop floor" component, terminal, and footprint tags. Then, later on, they want to start editing the drawing set over to actual customer component tag names. BUT, they want to be able to quickly flip back and forth between these two sets of tags AND they want the drawing set to be fully "smart" (i.e. cross-referencing, surfing, reports, etc) no matter which set of tags is displayed.
Another challenge...
Okay, this might work. Write an AutoLisp utility to save each set of tags to a piece of invisible Xdata on each component, terminal, and footprint. Then have another utility to map one set of saved Xdata values (ex: "shop floor" set) or the other set (ex: "customer" tag set) back into the TAG1/TAG2/P_TAG1 attributes. I roughed out a small suite of tools. Download the utility here. Give it a shot. I think it could work.
UPDATE: tweaked a bit so it can toggle "blank" tags
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Instant "Tags used" listing
June 8, 2006 02:46 PMby Nate HoltThis came up earlier in the week...
Problem: user needs instant "tags used" listing for a given component family type. User does not want to run a report and sort through the list or edit a "like" component and hit the project-wide tags in use button. Wants the info NOW!
Solution: write a little AutoLisp utility to scan the active drawing and query the active project's database to come up with a real-time, accurate tags-used listing. Outline of such a utility (that uses some calls from the AcadE "API" [see Electrical Help]) is here. It illustrates how to query the active drawing (using ssget and processing the component tags) and query the active project's scratch database to collect the tags for all of the other drawings in the project. The result is an instant, up-to-date listing of the desired information.
To test, open up an AcadE project. APPLOAD this utility. Then type FAMILY_TAGLIST [Enter] at the command line.
Don't be afraid to edit this utility to make it do other things. This stuff can really be fun!
UPDATE: the sample utilty has been updated to now include processing of terminal tags and PLCIO module tags.
UPDATE: updated to list terminal numbers used for each terminal "tag strip" listed
UPDATE: added display of "instance count" when same tag found multiple times
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AcadE Best Practices - season premier
June 2, 2006 06:32 PMby Nate HoltCheck out Robert Stein's first two installments of AcadE "best practices" here.