Properties of objects in CAD systems of OrCAD and Allegro printed circuit boards
When I trace a printed circuit board, I often want to do such non-standard things as, for example, changing the way a polygon connects to a specific contact, hide DRC errors when closing circuits to each other, add user comments to a specific topology object, etc.
Since I work in OrCAD, I’ll write about working in this program. I hope this will be useful to someone.
I found here how to get around the problem of losing information about assigning custom properties to individual components in a project. The PCB editor OrCAD offers a set of properties that can be assigned individually to various objects in a PCB design. Such properties are called “custom”. An example of assigning such a property to the selected pin of the connector for which I want to prohibit swapping (exchange between pins).
You can apply some useful properties to each object - for example, set a “special” thermal or continuous connection for a specific pin lying on a polygon, while all other pins will be connected to this polygon in a typical way, through standard thermal contacts.
However, such freedom in the assignment of properties is fraught with danger. If after some time the user continues to work on the project, then he risks forgetting about the added properties for specific objects. For example, my colleague recently forgot about the property “NO_DRC”, which he attached to one pin of the component, and which, “horrified”, completely cancels the checks for this object. If, when working on a project, a short circuit occurs between one circuit and another on this contact, the system will not signal this error. This can lead to inoperability of the board if such a circuit was not planned by the developer.
In principle, of course, it would be nice to accompany such “powerful” corrections in specific objects with a change in the name of these objects. For example, my colleague could name the changed pin something like PIN_WITH_NO_DRC_PROPERTY, and the component COMPONENT_WITH_NO_DRC_PIN, so that those who will use this project in the future can at least somehow see the “peculiarity” of this pin.
In fact, it’s very difficult for a person to keep in mind all the “special” places in projects to which he assigned user properties. Keeping a kind of log of added properties will also not be a guarantee against errors. After all, you can forget to make an entry in the journal, if it is a person, not a robot.
It turned out that it is much easier after a long break in working with a particular project to perform simple checks on added custom properties. This is very easy to do using the advanced OrCAD object search tool called “Find by Query”. Its launch from the Find panel in OrCAD version 17.2 looks like this.
Using this tool, I can generate almost any search query and immediately get acquainted with the results. In the left part of the dialog box, you must select the type of objects among which the search will be performed. In our case, I select the pins. Next, in the middle part of the “Fields” dialog box, you must select an object property that can take a specific value. In the figure, the section for custom properties is selected. At the final stage, the property itself is selected, which must be found. Which is convenient: only those properties that are really present in the project are visible in the list — in my case, these were NO_DRC and NO_SWAP_PIN. You can optionally enter the desired property value to narrow the search field. As soon as the request is formed, the result appears at the bottom of the window. By clicking on a particular line in the table of results, we move the focus of the screen to the object that has the desired property or satisfies the conditions of the search query.
As I discovered after some experimentation, the advanced search capabilities of OrCAD are very wide. For example: you can find in the project all the conductive lines of a given width. To do this, you need to form a search query (see picture). Using the SHIFT key in the list of found objects, you can select several objects at once and perform some action on them. For example, change the width of the conductor.
Search queries can be saved for future use as files on disk. It is very convenient. At least, I will now definitely check for the presence of the NO_DRC property, and other specific properties, not only in my old projects, but also in Internet reference designs in the OrCAD / Allegro format, when I take them as the basis for subsequent developments.
Since I work in OrCAD, I’ll write about working in this program. I hope this will be useful to someone.
I found here how to get around the problem of losing information about assigning custom properties to individual components in a project. The PCB editor OrCAD offers a set of properties that can be assigned individually to various objects in a PCB design. Such properties are called “custom”. An example of assigning such a property to the selected pin of the connector for which I want to prohibit swapping (exchange between pins).
You can apply some useful properties to each object - for example, set a “special” thermal or continuous connection for a specific pin lying on a polygon, while all other pins will be connected to this polygon in a typical way, through standard thermal contacts.
However, such freedom in the assignment of properties is fraught with danger. If after some time the user continues to work on the project, then he risks forgetting about the added properties for specific objects. For example, my colleague recently forgot about the property “NO_DRC”, which he attached to one pin of the component, and which, “horrified”, completely cancels the checks for this object. If, when working on a project, a short circuit occurs between one circuit and another on this contact, the system will not signal this error. This can lead to inoperability of the board if such a circuit was not planned by the developer.
In principle, of course, it would be nice to accompany such “powerful” corrections in specific objects with a change in the name of these objects. For example, my colleague could name the changed pin something like PIN_WITH_NO_DRC_PROPERTY, and the component COMPONENT_WITH_NO_DRC_PIN, so that those who will use this project in the future can at least somehow see the “peculiarity” of this pin.
In fact, it’s very difficult for a person to keep in mind all the “special” places in projects to which he assigned user properties. Keeping a kind of log of added properties will also not be a guarantee against errors. After all, you can forget to make an entry in the journal, if it is a person, not a robot.
It turned out that it is much easier after a long break in working with a particular project to perform simple checks on added custom properties. This is very easy to do using the advanced OrCAD object search tool called “Find by Query”. Its launch from the Find panel in OrCAD version 17.2 looks like this.
Using this tool, I can generate almost any search query and immediately get acquainted with the results. In the left part of the dialog box, you must select the type of objects among which the search will be performed. In our case, I select the pins. Next, in the middle part of the “Fields” dialog box, you must select an object property that can take a specific value. In the figure, the section for custom properties is selected. At the final stage, the property itself is selected, which must be found. Which is convenient: only those properties that are really present in the project are visible in the list — in my case, these were NO_DRC and NO_SWAP_PIN. You can optionally enter the desired property value to narrow the search field. As soon as the request is formed, the result appears at the bottom of the window. By clicking on a particular line in the table of results, we move the focus of the screen to the object that has the desired property or satisfies the conditions of the search query.
As I discovered after some experimentation, the advanced search capabilities of OrCAD are very wide. For example: you can find in the project all the conductive lines of a given width. To do this, you need to form a search query (see picture). Using the SHIFT key in the list of found objects, you can select several objects at once and perform some action on them. For example, change the width of the conductor.
Search queries can be saved for future use as files on disk. It is very convenient. At least, I will now definitely check for the presence of the NO_DRC property, and other specific properties, not only in my old projects, but also in Internet reference designs in the OrCAD / Allegro format, when I take them as the basis for subsequent developments.
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