💡 You can upload your construction plans digitally at CENDAS. To fully utilize all functions, the plans must meet certain requirements and be correctly exported from the CAD tool used.
Table of Contents
➡️ Supported CAD Tools
It is recommended to use tools such as Revit, AutoCAD, DDScad, or Trimble Nova CAD, as compatibility is particularly high with these.
📣 Note:
If you use another CAD tool and inconsistencies occur, please contact us and we will analyze the problem.
➡️ General Requirements for the Plans
- The CAD plans must be provided in DXF or DWG format.
- The plans must be 2D assembly plans (only for these can tasks be created automatically)
- Components are only recognized as such if they have been planned as CAD blocks. Primitives (simple lines, circles, etc.) are not supported!
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All plans or layouts you want to use in CENDAS must have a visible and printable (plottable) plan frame and no visible components may lie outside this frame.
Detailed Description of the Above Minimum Requirements
- The CAD plans must be provided in DXF or DWG format.
Is PDF also supported as a format?
Yes, you can also upload plans in PDF format. However, in this case, no components will be automatically recognized and you would need to create the components as tickets manually on cendas.app.
How do I export a plan in DXF or DWG?
- The CAD plans must be 2D assembly plans. Other types of plans can still be uploaded and visually displayed, but tickets will not be automatically created for these plans.
- For components to be recognized, they must consist of CAD components. Parts made only of primitives (simple lines, circles, etc.) are not supported.
What is a CAD component?
A component or insert in a CAD plan is like a prefabricated part that you can reuse repeatedly, similar to a standard component or part in the real world.
Imagine you have a CAD model for a building in which you design various technical systems. Instead of drawing a pipe, an outlet, or a pump every time, you can use already created components. These blocks represent these parts and are already drawn and specified.
These CAD components contain metadata that allows us to recognize them as connected objects (e.g., an electrical outlet).
A component can accidentally be broken down into primitives. By "exploding" the component, it is divided into its subparts (lines, circles, etc.) and the metadata is lost, so we can no longer recognize it as a component.
When you click on a component in AutoCAD (similarly in other tools), it highlights, and its attributes show that it is a block:
- All layouts/plans you want to use in CENDAS must have a plan frame and no visible components may lie outside the frame.
What is a plan frame and how do I create it?
The plan frame is a border that surrounds the plan.
- The CAD plans must be provided in DXF or DWG format.
➡️ Requirements for Optimal PDF Creation of the Plan
If the requirements are not met, a PDF will still be created from the plan and displayed online, but perhaps not as expected.
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XREFs (external references) are embedded in the plan.
Detailed Description of the Requirements
- All XREFs (external references) should be embedded in the plan, as otherwise they cannot be considered.
What is an XREF and how can I bind (include) it?
An XREF (external reference) is a feature in CAD (Computer-Aided Design) tools like AutoCAD that allows you to embed one file into another. It lets you reference external drawings, plans, or objects without copying them directly into your current drawing.
Imagine you have a main drawing showing the floor plan of a building. Now you want to create a separate file with the electrical plan of the building. Instead of copying the electrical plan into the main drawing, you can embed it as an XREF into the main drawing.
Embedding an XREF is relatively simple. In AutoCAD and most CAD tools, you follow these steps:
- Open your main drawing in AutoCAD.
- Select the "External References" or "XREF" option in the menu.
- Choose "Attach" or "Insert."
- Select the file you want to embed as an XREF.
- Set the placement and scaling options for the XREF in your main drawing.
- Confirm the selection, and the XREF is inserted into your drawing.
It works similarly in other CAD tools.
Note: Plans are converted to PDF as AutoCAD would do it. All common CAD programs also create AutoCAD-like PDFs.
Could my CAD program create the PDF differently than CENDAS?
It can happen. However, in most cases, these should be only minor differences if XREFs are embedded.
Possible reasons include:
Settings: CAD tools often offer various options for displaying graphics and line styles. For example, a setting in your CAD tool might display lines in black on screen but print them in gold when plotting (creating the PDF). CENDAS will only show the view present in the DXF/DWG file. In this case, the line would be black.
Different PDF conversion methods: CAD tools can use different methods to convert CAD drawings into PDFs. These methods may differ in accuracy, compression, or formatting, leading to different results. At CENDAS, we use the conversion method from Autodesk (AutoCAD, Revit) as the standard and generate PDFs accordingly. The result should still be the same or nearly identical to your CAD tool's result.
Can I use my own PDF (visual representation of the plan in CENDAS)?
Yes.
You can export your own PDFs and upload them to CENDAS to replace the automatically generated ones. It is important that the PDF has the same aspect ratio as the CAD plan.Instructions: 🔷Plan Requirements
- All XREFs (external references) should be embedded in the plan, as otherwise they cannot be considered.
➡️ Requirements for Optimal Analysis of a Plan (DXF/DWG)
If the requirements are not met, the analysis of the plan will still be performed, but perhaps not as expected. Analysis of the plan means the automatic recognition of components.
- The layouts have ≤ 10 layout viewports
- Plan size as DXF is < 1.5 GB and as DWG is < 150 MB
- No IDs are in the names of the components
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There are no anonymous components
Detailed Description of the Requirements
- DXF files must not be larger than 1.5 GB and DWG files must not be larger than 150 MB
How can I reduce my plan size?
The best way to reduce the size of CAD plan files is to delete unnecessary information and check the plan for issues. This varies depending on the CAD tool. Many tools have functions like "Clean" and "Audit" that can be used for this purpose.
Specific instructions for AutoCAD
CLEAN
1) Select the "Clean" function. If your AutoCAD version does not have this, there are various add-ons available for AutoCAD that you can install.
2) Select all options and click "Clean All". To ensure nothing breaks in the plan, test this command first on a copied version of the plan or create a backup of the plan first.
- Corresponding Autodesk instructions: https://help.autodesk.com/view/ACD/2020/DEU/?guid=GUID-62DDB935-61B1-49DA-8238-3EF1CC45259B
PURGE
Deletes duplicate objects and redundant geometries. It is recommended to back up the file beforehand. Components on locked layers cannot be purged. It is recommended to unlock these.
- Corresponding Autodesk instructions: https://help.autodesk.com/view/ACD/2020/DEU/?guid=GUID-A9927B3C-7C30-43FB-B6A9-29843B35001C
AUDIT
Checks for errors in the CAD file and fixes them.
- Corresponding Autodesk instructions: https://help.autodesk.com/view/ACD/2020/DEU/?guid=GUID-62DDB935-61B1-49DA-8238-3EF1CC45259B
Other possible measures:
- Instructions to further reduce the size of a 2D AutoCAD plan: https://www.autodesk.de/support/technical/article/caas/sfdcarticles/sfdcarticles/DEU/how-to-reduce-the-size-of-a-dwg-file-in-autocad.html
- Instructions to further reduce the size of a 3D AutoCAD plan: https://www.autodesk.de/support/technical/article/caas/sfdcarticles/sfdcarticles/DEU/Reducing-the-size-of-3D-DWG-files.html
→ If all these measures do not help, this workaround can be used:
1) Export the plan as PDF
2) Save the plan as DWG/DXF
3) Open the DWG/DXF and delete all layers that do not contain components (e.g., architectural layers). Delete all remaining geometries that are not components. Save the DWG/DXF
4) Upload the plan to CENDAS.
5) Replace the PDF with the PDF you created.
Specific instructions for Revit
Instructions to remove unnecessary information in Revit (like in AutoCAD) and reduce plan size:
- Revit 2023: https://help.autodesk.com/view/RVT/2023/DEU/?guid=GUID-4EBBDE76-E019-486E-BFBF-EE326CAAE2C4
- Revit 2022: https://help.autodesk.com/view/RVT/2022/DEU/?guid=GUID-4EBBDE76-E019-486E-BFBF-EE326CAAE2C4
- Revit 2021: https://help.autodesk.com/view/RVT/2021/DEU/?guid=GUID-4EBBDE76-E019-486E-BFBF-EE326CAAE2C4
- Revit 2020: https://help.autodesk.com/view/RVT/2020/DEU/?guid=GUID-4EBBDE76-E019-486E-BFBF-EE326CAAE2C4
- Revit 2019: https://help.autodesk.com/view/RVT/2019/DEU/?guid=GUID-4EBBDE76-E019-486E-BFBF-EE326CAAE2C4
- Revit 2018: https://help.autodesk.com/view/RVT/2018/DEU/?guid=GUID-4EBBDE76-E019-486E-BFBF-EE326CAAE2C4
- The layouts of the plans must not contain more than 10 layout viewports.
Further explanation
Layout viewports are areas in CAD software that allow you to display different views of a plan or drawing simultaneously. You can think of them as windows through which you can look at different parts of a drawing (model space).
Imagine you have a drawing of a house. With layout viewports, you can display different views of the house, such as floor plans, side views, or top views, side by side. Each of these areas is a layout viewport.
Since CENDAS must analyze the model space for each layout viewport, the analysis time increases with each layout viewport. The duration also depends on the size of the model space. Roughly, no more than 10 layout viewports should be present in a layout, as otherwise the analysis time might become too long.
- For optimal grouping of components, no IDs should appear in the names of components
What happens if IDs are present and how can I recognize them?
Simply put, IDs (identification numbers) are unique identifiers used to identify different components in CAD plans. They serve to distinguish individual elements and name them uniquely.
To recognize IDs in a CAD tool like AutoCAD, you can check the names of the components. IDs are often specific character strings or number combinations embedded in the names. For example, an ID might look like "1234" or "C-567". It is important to note that not all components contain IDs, but it is good to look for specific patterns or formats that might indicate IDs.
To remove IDs in AutoCAD, there are various methods. A simple way is to manually edit the name of each component and delete the ID from the name. You can use the text editor or renaming function in AutoCAD.
If IDs are present in the names, optimal grouping in CENDAS might not be possible. CENDAS tries to recognize and automatically remove IDs in names, but depending on the ID, this might not always be possible.
- For optimal grouping of components, no anonymous components should appear in the plan
What happens if anonymous components are present and how can I recognize them?
Anonymous components are elements in CAD plans that have no unique designations. They are marked by special codes beginning with a certain letter and a three-digit number, such as "*U###".
These anonymous components usually arise from certain actions during the CAD design process. For example, if a designer creates a block but does not give it a unique name, it is automatically marked as an anonymous block.
Since these components have no names, no names can be displayed for them and grouping is also not possible.
Note: The more layout viewports in the layouts and the more content (components, architectural drawings, etc.) in the model space, the longer the analysis phase will take.
- DXF files must not be larger than 1.5 GB and DWG files must not be larger than 150 MB
➡️ Requirements for Optimal Revision of a Plan (DXF or PDF)
Detailed Description of the Requirements
Revision Using DXF/DWG
If changes are made in the CAD plan, these can also be applied in CENDAS by re-uploading the DXF/DWG plan. The corresponding tickets and the PDF (visual representation) will also change accordingly.
If a DXF/DWG is replaced, it should have the same aspect ratio as the original plan.
More information
The original and new (revised) DXF/DWG CAD plan must have the same aspect ratio. In other words, the ratio between height and width must be the same in both CAD plan files.
If the aspect ratio is not the same, this would result in shifted tickets.
Note: Plans uploaded before 11/25/2022 may lead to unexpected results during revision.
Note: The fewer CAD tools involved in editing the plans, the more accurately the revision can be performed. This is because we consider metadata for the revision, which can be distorted by using different CAD programs.
Revision Using PDF
If changes are made in the CAD plan, these can also be visually applied in CENDAS by re-uploading the PDF plan. However, tasks will NOT be updated. Only the visual representation of the plan changes.
- If a PDF is replaced, it should have the same aspect ratio as the original plan.
More information
The aspect ratio of the new (revised) PDF must be the same as the original DXF/DWG plan file. In other words, the ratio between height and width must be the same in the PDF and the CAD plan.
If the aspect ratio is not the same, this would result in shifted tasks.
The new PDF or DXF/DWG must have the same aspect ratio (size/width) as the already existing plan.