topic Re: iLogic - CASE Statement Help in Inventor Programming Forum

iLogic - CASE Statement Help

arkelec — Wed, 14 Jun 2017 07:24:53 GMT

As a rookie in Inventor VBA & iLogic, can I ask for a quick steer on the right approach to solve what I think is a fairly simple problem.

I need to set a dimension in an iPart to be conditional on the "Length" parameter (this is the actual parameter name).

I have some other parameters, one of which is used as the dimension in question, it's called "Dist_1".

Dist_1 will be either of two values:

Condition 1: 0
Condition 2: The result of another calculated formula within the iPart parameters

The iPart has 20 or so different lengths programmed into it. For every length which is a multiple of 100mm, I need to set Dist_1 to condition 2. For all others, condition 1.

A bit of net trawling suggest using the CASE function. I have created an iLogic rule containing the following code:

Select Case Length
Case "100"
Dist_1 =Dist_2
Case "200"
Dist_1 =Dist_2
Case "300"
Dist_1 =Dist_2
Case "400"
Dist_1 =Dist_2
Case "500"
Dist_1 =Dist_2
Case "600"
Dist_1 =Dist_2
Case "700"
Dist_1 =Dist_2
Case "800"
Dist_1 =Dist_2
Case "900"
Dist_1 =Dist_2
Case "1000"
Dist_1 =Dist_2
Case "1100"
Dist_1 =Dist_2
Case "1200"
Dist_1 =Dist_2
Case "1300"
Dist_1 =Dist_2
Case "1400"
Dist_1 =Dist_2
Case "1500"
Dist_1 =Dist_2
Case Else
Dist_1 =0
End Select

Clicking Save & Run does not generate any errors but assuming the above is correct, I'm not sure what to do next.

Some questions:

Is the syntax for the length values correct (are the " " needed & do I need to specify the units used in the parameter setting - i.e. mm)?
How do I link the dimension in the sketch to the output of the iLogic rule?

Thanks 🙂

Re: iLogic - CASE Statement Help

MechMachineMan — Wed, 14 Jun 2017 14:58:46 GMT

1. The quotation marks depend entirely on what data type you are comparing. Given that it LOOKS like you are using Length as a parameter, I believe that means it's type will be "DoubleForEquals". Not sure what this means for the results of your code, but you can always write a simple example program to test it out.

2. Get the rule to set the PARAMETER, and have go into your sketch and make it reference that PARAMETER, like intended.

Re: iLogic - CASE Statement Help

arkelec — Wed, 14 Jun 2017 16:16:27 GMT

Thanks for replying.

I'm not sure what point one of your answer means but agree it can be tested.

MechMachineMan wrote:

2. Get the rule to set the PARAMETER, and have go into your sketch and make it reference that PARAMETER, like intended.

This is the bit I can't seem to work out - "Get the rule to set the PARAMETER". How & where is this done?

Dist_1 & Dist_2 are already parameters (user defined) & the sketch dimension (d27) already references Dist_1.

I assume that this will all work with an iPart?

Re: iLogic - CASE Statement Help

arkelec — Wed, 14 Jun 2017 18:17:49 GMT

OK, I think the problem might lay with updating.

In the "Driving Rule" column in the parameters box, it lists the name of the rule I created.

I also created a form with the parameter "Length" visible so when I change that from 500 to 550mm, the DIST_1 value changes from Dist_2 to 0 (as per the rule code).

But when I "Change Component" in an assembly, the 0 value (Dist_1 parameter) is not updated.

Edit:

There is something else wrong. It seems Dist_1 is either equal to Dist_2 or 0, but not both when there are two or more instances of the iPart in the same assembly.

Re: iLogic - CASE Statement Help

rossano_praderi — Mon, 19 Jun 2017 07:51:51 GMT

Hi,

I just would like to give you an alternative to "Select case" only for your information.

This is an "if" operator also called "ternary" with which you can get a shorter syntax for your code.

(https://docs.microsoft.com/en-us/dotnet/visual-basic/language-reference/operators/if-operator)

I'm also used the "mod" operator to check if the given number is a multiple of 100.

(https://docs.microsoft.com/en-us/dotnet/visual-basic/language-reference/operators/mod-operator)

Dist_1 = If((Val(Lenght) Mod 100) = 0, Dist_2, 0)

This doesn't solve your last question but can be helpful to make more readable your code.

Bregs

Rossano Praderi