DRC incorrectly shows Net to close to Net

[RobinJet]

Hi all!

I have this project which has Multisim as well as a Ultiboard project files.

Now I have drawn tracks from one SMT chip but DRC keeps telling me that a Net is to close to a Net.

I have verified that it comes under the error category "copper objects close to each other" because when I turn on that filter, all of my DRC errors disappear.

By default I've kept all clearances to 8 mils but I still get errors.

I have even set the clearances to 1 mil and done a "DRC and Netlist check" but the errors still show up.

Any genius knows which other setting/procedure can let Ultiboard recheck the copper clearances?

Please look at the images:

1. PCB view with DRC window showing errors. Note the red circles around the pins aswell as around some of the tracks.
2. PCB view with DRC window with filter "copper objects close to each other" enabled. Note the lack of errors!
3. Main menu > Options > PCB properties > Design rules tab. Note the clearances.   Also view of the other Design rules when scrolled down.

Any help will be readily accepted!

Robin.

[kittmaster]

that would only work if you had the "multiple clearances" box checked, which it isn't

I would restore those and use the "spreedsheet" view and go to the "nets" tab set the clearances properly.

If you want to become a power user, the spreadsheet view is your answer, it works for the most part EXACTLY like an excel row and table headers. In fact, I'm betting they used the excel object data to create that section of the software since it almost that easy to use.

The quick and dirty is to once you get to the spreadsheet area above, click on the trace clearance column name at the top to highlight the entire cell block below, then while highlighted, click in any highlighted cell, and then type the number you want, all values will change to that value you just typed.

If you really know excel, then you can get more creative with multiple clearances by sorting and control shift techniques.

Greetz

Message Edited by kittmaster on 11-29-2007 09:11 AM

[RobinJet]

Hey Kittmaster!

Thanks for your great tip! I did'nt understand (or discover) that the clearance was also a property that had to be set per trace. I thought it was a setting per PCB so I was frustrated that it did'nt work!

So now I have eliminated all the errors by doing what you said - the quick 'n dirty way - clicking on the Clearance column header and typing a value - 5 mils worked just right for me.

Oh and BTW, They have not used the Excel component becuase it is not possible to 'include' it in any app you want because MS does not freely package it as a COM/ActiveX control (not that I know of at least!) although there are a lot of 3rd party Grid controls available for use in any Windows/Web app.

Although you can write code to run in the Excel program - like scripts or extensions - or a full custom app - but understand that your program will run inside of Excel but Excel will not run inside an App.

If you feel that it is like Excel, these are just normal grid control functions - multiselect, multiedit etc.

I suss that the have built NI EWB tools in Visual C++ because it is usually the tool of choice for such hardcore CAD software running on Windows. Apple Mac has Xcode.

I know becuase I also happen to be a developer!

Have a nice day!

[kittmaster]

Very good to know, glad it worked.

I wasn't sure what level you were at, so I figured that was the best wasy to describe it......;)

You can't script or copy and paste any of the data as you mention, though it does have the excel...."feel".....:)

Have a good day

[RobinJet]

What I meant by scripting is that you can write scripts that run in Microsoft Excel! (2003/2007)

I was not referring to Multisim/Ultiboard! I don't think they have any APIs do they?!

Try Visual Studio 2005/Visual Studio 2008 Express Editions that you can download for free.

In VS 2008 you have "Tools for Office" (VSTO) integrated, whereas in VS 2005 you have to purchase an edition which has VSTO.

BTW you write VHDL? Or was it Verilog? I just know a bit about HDLs - How's it done?

[GarretF]

Hi Robin/Chris:

I don't want to but into your conversation, but I will because it isn't well known. As of version 10, Multisim has a COM API. With it, you can open an existing circuit and perform some simulation. You can also use the API to simulate a SPICE netlist using 'Nutmeg' commands.

[kittmaster]

Garret,

I figured it might be since it shared a lot of common elements, where is this documented? How do you use it?

Do tell!

[lacy]

I don't like to jump onto someone else's thread, but since we are discussing DRC errors and thier causes I have a question.

 I was exporting a simple circuit from Multisim to troubleshoot a question on the forum. What I did was have 2 resistors in series and then have this in parallel with another 2 in series. I then exported this to Ultiboard and autoplaced them. The result was 3 resistors R1-R3 stacked one above the other with R4 directly across from them. The DRC flag came up and said that the 3 stacked resistors were too close and almost overlapping. My autoplace component spacing was set to 20 mill, so why wasn't that used to separate these components? Why did it ignore this setting?

If this is a known issue please let me know

[kittmaster]

I would post up the original file for review if you could

[GarretF]

Chirs:

I don't know of any documentation. However, there are only a few commands and one of the nice things about COM is that it is 'self-documenting.' The name of the Component Name is 'NI Circuit Design Suite Multisim 10.0. If you have questions, post them on this forum and I'll try to answer what I can.

As for the Nutmeg commands, have a look at The Spice Page
for an overview. The syntax and commands for Multisim is sometimes a little different. The best way to see the commands is to open a circuit, open the analysis dialog, setup the options for the analysis you want to perform, then select the Summary page, and in the tree, you will see an item "Representation as SPICE commands." This should give a better indication of what input to give to Multisim.