Cabling

[KPMcDonnell]

I have been tasked with creating cabling harnesses for a next generation space telescope for NASA at Goddard Space Flight Center.  Our traditional method of harness manufacture is to build a mock up structure, run all the cables on the mock up, and then transfer the harnessing to the actual spacecraft.  With this method we have to do an immense amount of guesswork and add in a lot of extra room to make sure that everything will fit. 

As of right now there are many many areas for improvement within the cabling module and Creo itself that I would like to submit for submission.

There is currently no method for making changes to a cable short of deleting it and rerouting it manually.  NOTHING updates parametrically.  This is a massive departure from the way that Creo works and markets itself.  Please change this.

If I run a cable and then have to change the spool or diameter - Delete and Rerun

If I run a cable and need to change the end location - Delete and Rerun

If the Connector moves, the cable will not reroute properly - It will keep the old route and then "add" another section from the old location to the new location - Delete and Rerun

I would also like to be able to calculate the mass of a cable.

In the photos attached you will see that I created a straight 1,000 mm cable run in order to test the mass calculating capabilits of Creo, I then calculated using Excel what the mass of the cable should be if density is calculated by unit length or unit volume.  I couldn’t obtain results that are in line with what Creo provides. 

I then looked around and found different values for density that were reported by Creo, both in the cabling module and the standard module.  I went back and calculated the mass of the cable with the many densities that I found within the module.  I couldn’t get any results that match my own calculations. 

• Why are there so many different densities?  Shouldn’t it be something that is set once?
• Is mass something that Creo can actually calculate?  Even in the standard Creo module I oftentimes have to “trick” Creo into giving me a correct mass or have to calculate it myself.  I’ve spoken with many designers here and have been told to not have too much confidence in Creo’s mass reporting function and to always double check or calculate the results yourself.
• Is there anyone at PTC that knows the cabling module that I can speak with?

I have provided video to PTC showing them these issues.  Please see PTC Technical Support Case #14610212

[RaymonDavies]

Agree, you got a vote from me. Maybe they should remove 'Parametric' from the name, and just call it Creo Modeler. It seems the parametric part has been forgotten. Unfortunately, we ended up developing our own Cabling applications with Toolkit. 

[KPMcDonnell]

I'm in a bind right now, I'm running cables to electronics boxes that are constantly moving. A simple move or rotation of a box will turn my carefully routed cabling assembly into spaghetti. I have been unable to figure out a way to get cable runs to reroute when the location of connectors change, and am at the point where I think that that functionality is simply not present in the cabling module. Are there an users groups for cabling that have experienced the issues I am having? @RaymonDavies - I am the only person at my work who uses the cabling module, I was hoping to carve out a nice specialty niche for myself as a cabling expert here, but have run into a great many roadblocks. How long did it take you to develop your own cabling application? What aspects of cabling do you use your application for? We would like to be able to use the application for developing harnesses from start to finish, but right now we would be content with running paths in the assembly and generating a mass.

[BillF]

There are people who use Cabling (I am primarily on the schematic end of things) that you can connect with. 

 - Consider joining the Routed Systems Technical Committee.  It has shifted more towards user information than the old "recommendation for direction" plan that it used to have.  There is a monthly meeting via Webex.  No requirements for attending specific conferences but it is moving to having sessions where people can talk about what they are doing on a user to user basis, especially in the January conference.
 - Consider getting help via a consultant.  The software is complex and sometimes different methods work better for different people's needs.

[BillF]

oops, forgot to send the link for the technical committees.

https://portal.ptcuser.org/technicalcommittees

[KPMcDonnell]

Thank you for getting back to me, I will sign up for the technical committee

[ptc-4424533]

For the initial message: The "density" that you put into the Spool definition dialog is actually "mass per unit length".  (make sure you also turn on the "MASS_UNITS" column.)  The density that the Creo "Mass Properties" report gives you is calculated based on taking the cable length, multiplying by the entered mass-per-unit-length, and then dividing by the actual volume of the 3D-modeled harness (which means that two harnesses with the same Spool might have different reported densities...)

As for the cable explosion woes: Cable harness models in Creo are extremely dependent on the references.  It's best to use datum references that are independently defined (that is, they use Part or Assembly Default Datums) rather than tying your cable routing to geometry.  MAKE EVERY POSSIBLE EFFORT TO AVOID EXTERNAL REFERENCES (a good policy for Creo modeling in general, but vital for cable harness models.)  

An important thing to remember is that you don't actually need to Designate Components.  When Routing a wire or cable, you can pick "Allow Location" in one of the boxes, and then you can choose "add location" when picking the start or end points and create a new location on a coordinate system.  And using coordinate systems as references makes updating the harness MUCH easier, because you just move the coordinate system (versus having to re-define and re-designate a Component.)

In general, modeling your harness using completely independent datum features is far more robust than using geometry.  It can be a pain in the seat to update the cables by moving datums around -- as RaymonDavies points out it basically stops being parametric -- but at least it keeps your cable model from exploding and dying when someone changes a fillet radius.  As you get more familiar with how the cabling system uses its references (and, of course, as the design settles down) you can start tying the datums to geometry references (or even using the geometry as references again, if you like to live on the edge, as it were.)

[olivierlp]

Hello,

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