Revit Dynamo

[Anonymous]

I'm trying to output values from Revit to an excel spreadsheet in tabular form. And then from there be able to alter the data in excel to change the data in the model. I understand the basics of Dynamo, and I can get this feature working for lots of different parameters, for example changing the length of an Air Handling Unit or something from a family. 

The problem I'm having is when I try to do this for the flow rate (in L/s), it messes up the values. For example, if I set the supply air (a parameter I created, then set it to instance rather than type) to 230L/s and then put a "watch" block on the value, it will say it is 8.12 (approximately a factor of 28.3 smaller).

Then when I have it outputting to an excel sheet it does the same. When I set it to read from the file it does the same thing. For example, if I change the 8.12L/s from above to 68L/s and then run it, the supply air will show as 1925.55L/s in the model (approximately a factor of 28.3 larger).

I've checked for any differences in units and it all seems to check out. I've also done this for other measurements and it works fine, so I'm not sure why this problem is occurring just for the flow rates.

Thanks

[Anonymous]

I've noticed this a few times while working with Dynamo.  Rather than trying to understand what was going on, I added a simple "*" function to multiply by a factor that would get me where I wanted to go.

By the way, I've tried to do this very thing you're doing: sending data out to Excel, having Excel perform a function, and then pulling the data back into Revit, and it would invariably lead to a nasty recursive loop in which Excel and and Dynamo were endlessly changing the same parameter back and forth, and I'd have to kill the process in order to stop it.  In my case, i was trying to create link Thermostats and HVAC Zones to VAV Terminal Units, so that the names would match the VAV.  I was using Excel to perform a VLOOKUP, but after encountering problems I abandoned Excel and created my own "VLOOKUP" in Dynamo with a very large array of String.IndexOf, IndexOf, and List.GetItemAtIndex nodes.  I didn't think it was possible when I started out, but the Dynamo interface is so conducive to trial-and-error problem solving that I eventually figured it out. 

[robert.klempau · Accepted solution]

Hello @Anonymous and @Anonymous,

A guy I know (Taco Pover) wrote this on the Dynamo forum:

"You can always figure out the conversion by setting it to 1 and then see what shows up in Dynamo or vice versa.
Or you could use one of the nodes in the MEPover package to get and set the values as you see them in the Revit UI:" 

Please have a look at these packages.

The might help to solve your problem.

Please let me know if they do so I can tell him.