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 Post subject: Hierarchy - disabling or deleting global nets?
PostPosted: 04 Dec 2016, 23:00 
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Joined: 13 May 2013, 21:02
Posts: 10
Hi,

I am building a multi-page schematic with multiple hierarchical blocks. I'd like to assign each blocks' ground manually but DT wants the blocks ground to be global. How can I un-globalize a net once it has been made global?

Thank You,
Mike


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 Post subject: Re: Hierarchy - disabling or deleting global nets?
PostPosted: 05 Dec 2016, 07:46 
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Joined: 20 Jun 2015, 14:39
Posts: 943
Any Net connected to a Net Port is global so you will have to create an internal hierarchy ground Net and give it a unique name (e.g. "GND_H1").

Changing a global Net to a local Net inside a hierarchical block
1) Delete the desired global Net's Net Port and the wire connecting it to a component's pin, then right-click on the component's pin and select Add to Net... in the pop-up menu.
2) In the Net dialog window click on the [+] button.
3) In the Net Name dialog window enter a unique name (e.g. "GND_H1") and select OK. A different local Net name must be used for each separate hierarchical block (e.g. "GND_H2", "GND_H3", etc.).
4) In the Net dialog window enable the [X] Connect without Wire option and select OK.
5) Check the upper-level schematic sheet(s) where this hierarchical block has been placed to make sure that the global Net has not been accidentally renamed.

For other identically-named Net Ports (same global Net) in the hierarchical block
1) Delete the next identically-named Net Port and the wire connecting it to a component's pin, then right-click on the component's pin and select Add to Net... in the pop-up menu.
2) In the Net dialog window select the new local Net in the Select Net drop-down list (e.g. "GND_H1"), enable the [X] Connect without Wire option and click on OK.
3) Check the upper-level schematic sheet(s) where this hierarchical block has been placed to make sure that the global Net has not been accidentally renamed.
4) Repeat as needed.

Connecting the new local Net to the outside world (optional)
1) Place a new hierarchy connector and give it a name not already used by any other connector of the same hierarchical block. It can, however, have the same name as another hierarchy connector of a different hierarchical block (e.g. "GND").
2) Right-click on the new connector's unconnected pin and select Add to Net... in the pop-up menu.
3) In the Net dialog window select the new local Net in the Select Net drop-down list (e.g. "GND_H1"), enable the [X] Connect without Wire option and click on OK.


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Last edited by Tomg on 06 Dec 2016, 14:04, edited 4 times in total.

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 Post subject: Re: Hierarchy - disabling or deleting global nets?
PostPosted: 05 Dec 2016, 20:53 
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Joined: 13 May 2013, 21:02
Posts: 10
Tom, thank you so much - makes much more sense now :-) I'll go editing my schematic now that I understand what I am seeing.

What's the industry best practice for dealing with hierarchy in schematic capture? (I forget since I don't usually work in hierarchy often). Do all layout packages (EAGLE, Altium etc.) treat net ports of the same name as inherently global?

Mike


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 Post subject: Re: Hierarchy - disabling or deleting global nets?
PostPosted: 06 Dec 2016, 07:59 
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Joined: 20 Jun 2015, 14:39
Posts: 943
mikez wrote:
"...What's the industry best practice for dealing with hierarchy in schematic capture?..."
Unfortunately, my understanding of hierarchies is limited because I have very little experience using them. I am also ignorant of any industry-wide best practices concerning hierarchical design, but perhaps other forum members have some information they can share with us.

mikez wrote:
"...Do all layout packages (EAGLE, Altium etc.) treat net ports of the same name as inherently global?..."
Your guess is better than mine.

p.s. I stumbled over another way to disconnect a global net within a DipTrace hierarchical block, which is similar to the procedure above with the added possibility of getting you into trouble if you're not careful...

Another way to disconnect a global net within a DipTrace hierarchical block
1) If a Net Port has several connecting wires, delete the Net Port but not the connecting wires.
2) Right-click on one of the connecting wires and select Properties... in the pop-up menu.
3) In the Net Properties dialog window, enable the [X] Rename Related Wires Only and [X] Connect Nets By Name options, type in a new local Net name at the top (e.g. "GND_H1") and click on OK. As long as there are no other Net Ports attached to those connecting wires, the separation from the global Net should be successful. Of course, connecting the local Net to the outside world will require a new hierarchy connector.
4) Check the upper-level schematic sheet(s) where this hierarchical block has been placed to make sure that the global Net has not been accidentally renamed.

Note: Watch out for empty boxes [] being displayed at the end of hierarchy block connector pins wherever that block may have been placed (i.e. higher-level hierarchical schematic(s) or the main schematic). This indicates that the previous connection to the outside has been severed, even though a pin might appear to be touching a wire.

p.s.s. I cleaned up the first procedure to make it a little more readable.


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 Post subject: Re: Hierarchy - disabling or deleting global nets?
PostPosted: 08 Dec 2016, 02:34 
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Joined: 14 Jun 2010, 06:43
Posts: 2762
mikez wrote:
What's the industry best practice for dealing with hierarchy in schematic capture? (I forget since I don't usually work in hierarchy often). Do all layout packages (EAGLE, Altium etc.) treat net ports of the same name as inherently global?

In the beginning the hierarchy didn't support global nets. All blocks had its own ground, users needed to connect block's ground to main ground through hierarchical pin. The same situation was with power net(s). Users complained that was not convenient, we investigated the issue and implemented global nets. Other CADs (for example OrCAD) behave in the same way with global nets.


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