Hi JoelMckone,
Typically we would create a user parameter in the assembly (ex: Length_IAM) , and then include that parameter in the form. Then have a rule in the assembly that triggers on the change of Length_IAM and pushes its value to the Length parameter in all of the parts to be adjusted.
If the Form Rule resides in the assembly you could use something this, and Length_IAM would update automatically:
Length_IAM = Length_IAM
Parameter("Test_Part1:1", "Length") = Length_IAM
Parameter("Test_Part2:1", "Length") = Length_IAM
Parameter("Test_Part3:1", "Length") = Length_IAM
InventorVb.DocumentUpdate()
If it is a Global form External rule I think it would be like this, and you'd need an Apply button to run the rule.
(I might be forgetting something, here, working form memory, I didn't verify this)
Parameter("Length_IAM") = Parameter("Length_IAM")
Parameter("Test_Part1:1", "Length") = Parameter("Length_IAM")
Parameter("Test_Part2:1, "Length") = Parameter("Length_IAM")
Parameter("Test_Part3:1", "Length") = Parameter("Length_IAM")
InventorVb.DocumentUpdate()
I hope this helps.
Best of luck to you in all of your Inventor pursuits,
Curtis
http://inventortrenches.blogspot.com