algorithmic modeling for Rhino

How to connect to Excel, text files or other external data

Grasshopper can connect to many external data sources. Many times these connections can update real-time. Both reading from external data or writing data out of Grasshopper is possible. It seems that a connection to Excel spreadsheets, text files and other software are most common.


Excel and other spreadsheet programs:

A plug-in is required to read and write from/to Excel.  The current gHowl plugin is the most common. While gHowl connects to many sources, there's a spreadsheet component built in that may get you where you want to go. You can read from or create Excel data real-time. To give this a try, see the gHowl group.


At the moment gHowl uses OpenOffice for its spreadsheet support (even with Excel), so you might want to download that if you don't have it installed on your computer already. It's free and you can get it at


Reading data from text files:

David Rutten has made reading data from external text files easy.  Use the built-in Read File component. This component is in the Params toolbar.  The component will continuously read the contents of the specified text file. 



Writing data to text files:

You can write out to a text file from Grasshopper using the panel component. Any input to the Panel component can be streamed out to a text file by right-clicking on the Panel component and selecting Stream Contents.



Connecting to other software products:

Depending on the product you are trying to connect to, you may use a number of strategies.

  1. If the other product can read or write text files, then you can use the strategies above to connect the products together.  This is a good strategy for many products including Processing.
  2. The gHowl plugin has many different ways it can communicate with other products including UDP port processing.
  3. If the other product has a .NET interface, use the Vb.NET or C# code components in Grasshopper to attach to other products through the .NET API.


Connecting to hardware and the outside world:

If you would like to connect Grasshopper to sensors, controllers or other machines in the real-world there are a number of controls you can use.  Currently there are two plug-ins that make this connection easier, see gHowl plugin and the FireFly arduino interface.



Last updated by Jody Mills Dec 20, 2010.





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