What you probably don’t care to know about ParamOnLine in Plant 3D

Every now and then we get a random urge to answer a question no one asks, such as when the Fixed Issues for P&ID say, “The order of assets in P&ID Line List is based on the direction of the flow now, that is from upstream to downstream.” We feel like diving in to figure out what changed. To be fair, I’ve had the urge to resolve this for a while, and the recent update provided the excuse. One of the things I enjoy about working with Owen Whitehouse at Applied Software is that when one of us makes a comment about something like this, both of us end up digging into it separately, unaware of the other’s efforts.

To provide a little context, if you open up the P&ID database (ProcessPower.dcf, I’m using SQLite Expert Personal) to the EngineeringItems table, you’ll see a column ParamOnLine. This is where the story starts…

We found the article on AKN (Autodesk Knowledge Network) and it helped a little bit, but we needed more info.

https://knowledge.autodesk.com/support/autocad-plant-3d/learn-explore/caas/sfdcarticles/sfdcarticles/AutoCAD-P-ID-Wherefore-is-the-property-ParamOnLine.html

Here are the key takeaways. Note that to get the actual coordinates for valves, you would need to use the AutoCAD api to read the position of the linesegments, but if you’re doing that, you could just read the coordinates of the valves directly.

The Integer value is the segment of the line that contains the inline asset. This comes from using the AutoCAD api, where each segment in a polyline has a zero-based index. The indexes are identified with multi-leaders.

The decimal value is a percentage of the overall distance. Because this needs to work both on metric and imperial projects, the developers needed to use a scale factor rather than an exact measurement.

To convert to an actual distance, we multiply the scale factor * the overall distance (red dimensions). The distance is measured from start of the segment for the line to the start of the inline asset.

Now that we have that resolved, be sure to check back for our next article that talks through how to migrate shared content from Plant 3D 2021 to 2022.