technologyspotlight AUTOMATION - Part II Using Visual Basic in ESPRIT It s not just for the gurus! Part II The story goes like this:

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1 DAN PARRY - manufacturing engineer with Belvac Production Machinery, Inc. Using Visual Basic in ESPRIT It s not just for the gurus! Part II The diverse world of CNC programming and machining is forever evolving. As machinists and programmers, we have more power and technology at our fingertips on a daily basis than our predecessors saw in entire careers. Innovation is delivered by the truckload with every new CAM software release, cutting tool development and cutting-edge machine design. One result of this inundation of progress is the necessity of choice. We must choose which of these ingenious tools best suits the interests and goals of the companies we strive to make successful. When it comes to CAM, I know my company made The Right Choice with ESPRIT. In Part I of this article, I made an effort to entice those who are aware of ESPRIT s ability to implement Visual Basic into the programming environment, but who may think they are not capable of doing so, to give the process a try. I understand this can t-do mentality because I once entertained it myself. As a programmer, I understand the daily life spent chipping away at a list of ever-growing demands that seem to never diminish. Even if I thought my intelligence level was high enough to learn another programming language, when would I have the time to learn and apply it? These thoughts remind me of a little story about a king and a woodcutter. The story goes like this: One afternoon, the king went for a walk in the woods near his castle and he came upon a man who was working feverishly, sawing down a tree. What are you doing? the king asked the man. Can t you see? came the impatient reply from the man, I m sawing down this tree! You look exhausted! the king exclaimed. Then the king asked, How long have you been at it? Over five hours, the woodsman replied, and I m beat. This is very hard work. Well, the king suggested, why don t you take a break for a few minutes and use those minutes to sharpen your saw? I m Parts sure, machined explained the in king, ESPRIT that by would Central make Utah your Tool. sawing go a lot faster. The man looked the king in the eye and said angrily, I don t have time for a little thing like sharpening this saw. I m too busy sawing! Surely, if this very busy, powerful king could take the time to walk in the woods, which to him must have been like pausing to sharpen his saw, then it makes sense for each of us to take the time to reflect upon the benefits we can gain from doing the same. It wasn t until I decided to sharpen my saw that I realized I didn t need to learn a new programming language to get started and, thanks to DP Technology, you don t need to fluently understand Visual Basic to start using it in ESPRIT. As illustrated in Part I of this article, there are enough predefined functions and expressions to painlessly set anyone who wants to automate their programming process on the road to success. In Part I, I used the Expression Builder to apply if statements. The focus was on ESPRIT s ability to automatically set the lead-in/lead-out fields of a contouring page based on the properties of a milling feature. While the power and simplicity of the if statement are matched by few, sooner or later an endeavor for less clicks and more automation will require even more functionality. This article will cover a division of that next level. 1

2 In Part I, the if statement was used to determine if a feature is open or closed. Depending upon whether or not the result of testing the feature is true or false, the lead-in/ lead-out properties were set accordingly. In this example, we will explore the possibility of adding another condition by creating a custom function within the API and then calling that function from within the technology field. Before a function can be called from within a technology field, a few settings within ESPRIT must be turned on. First, check the Show Rule Processor Project in VBA box within the KnowledgeBase Document Setting dialog box shown in Figure 1. Figure 1 It is necessary to close ESPRIT and then open it back up before the KBM (Knowledge-based machining) Rule evaluator can be seen in the Visual Basic editor. Once ESPRIT is reopened, it is a good idea to verify that the change has been made by opening the editor (ALT > F11 or Tools > Macro > Visual Basic Editor). There should now be three VB Projects: the default project (shown in Figure 2, encompassed by the blue box), the KBM Rule Evaluator (shown in Figure 2, encompassed by the red box) and the local project (shown in Figure 2, encompassed by the green box). Another setting within the KnowledgeBase document settings to be aware of is found on the File Locations tab. The two locations noted on this tab should be the same and should display the location of the modules within the KBM Rule Evaluator. Modules/functions can be added to the KBM Rule Evaluator in one of two fashions. A new module can be inserted through the VB Editor (Right click on KBM Rule Evaluator > Inset Module) and saved in the same file location set in the KnowledgeBase Document Settings. Another method for adding modules/functions to the KBM Rule Evaluator is to create a new text document in the directory set in the KnowledgeBase Document Settings. Once the text document is created, replace the.txt extension with.bas; restart ESPRIT and the new module will appear in the KBM Rule evaluator. Once a new module has been added to the KBM Rule Evaluator, it is time to expand on the logic used to automatically set the lead-in field of a Contour Milling operation. To do this, the module must be defined as a function and given a name. It is best to name the function and the module after the task for which it is being used. To name the module, simply click on it and type the name using the Name Property of that function (shown in Figure 3). If the Properties Window is not visible, simply turn it on Figure 3 Figure 2 2

3 Figure 4 by clicking View > Properties Window from within the VB Editor. The next step is to begin describing the function by stating a Public Function containing the object that will be evaluated. For this example, we will use the following to begin our function: Public Function LeadInSelect (Feature As Object) As Long Through closer examination of creating the function, there are a few fundamentals that, when properly understood, will carry over into future function creation and macro writing. Firstly, the use of a Public Function is necessary so that it can be called from anywhere within ESPRIT. Without the keyword Public, the function can be used only with the module in which it was created. Next, LeadInSelect is the name that will be used within the technology field to call this particular function. Thirdly, Feature As Object is the object that will be used to evaluate the properties of the chain to which the contour milling operation will be applied. An Object as defined by Microsoft is a structure containing data and methods that manipulate the data. Lastly, the Long data type will be used. The data type of a programming element refers to the kind of data it can hold and how it stores that data. For a list and detailed explanation of the different data types that can be used, search data types in the ESPRIT API and Macro Help. The next step in creating the function is to declare the variables that will be used. A variable is declared in order to specify its name and characteristics. The declaration statement for variables is the Dim Statement (Dim is short for dimension). The Dim Statement s location and contents determine the variable s characteristics. In the case of this example, it is necessary to use the variable as shown below. Figure 5 to how they will be used. A closer look at EF illustrates that we will be accessing the Esprit.FeatureChain Class by using it as a data type. The Esprit portion of Esprit.FeatureChain refers to the Esprit Library. One way to identify which Class Members belong to a specific Library is by using the Intellisense utility within the editor. The Intellisense utility is initiated when the user types a. after the name of a Library, as shown below in Figure 4. Another way to understand which members are included in the FeatureChain Class is to type F2 or select Object Browser from the View menu within the VB Editor. By selecting Esprit Library from the pulldown menu on the search tool within the Object Browser, the Feature Chain Class can be quickly found. Once the class is located, its members are displayed in the window to the right (shown in Figure 5). Reference the ESPRIT API and Macro Help for further Object Browser information. Next, it is necessary to Set the Feature Object equal to the variable in order to define it. To get the IsClosed Property of the Feature, it is necessary to cast the Feature Object into a Feature Chain. Otherwise, ESPRIT will not know the element for which we want the IsClosed Property. Setting the EF variable equal to a Feature is shown below. Dim EF As Esprit.FeatureChain Set EF = Feature When it comes to naming variables, it is up to the user s discretion, but it is also a good idea to name them according Now we can begin expanding on the if statement. The first part of our logic states that if the IsClosed Property of the 3

4 feature being evaluated is false, then we set the lead-in as equal to Tangent. In order to specify which lead-in type will be used, the corresponding enumeration must be specified. In the ESPRIT API and Macro Help, a list of Constants can be found. Within each Constant, the enumeration list is present. For example, to find the enumerations for the lead-in parameter, open the ESPRIT API and Macro Help to select the API Reference section and expand the Enumeration list. It is here that espmillleadintype Enumeration is found. It is then shown that espmillleadintangent = 11 and espmillleadindistance = 0. The above will be described in our function as seen below. If EF.IsClosed = False Then Next, we will clarify the result of the lead-in based on whether the IsClosed Property of the feature is true. If so, the lead-in will be set to Distance or a 0 enumeration. Note the keyword Else is actually written as opposed to being illustrated with a comma as was done in Part I. Else LeadInSelect = 0 The next step is to add the final condition. To accomplish this, another if statement is used. It is not possible to apply multiple if statements using the Expression Builder; thus, it is necessary to create the function here and call it from the technology field. This final condition is shown below. It explains that if the Feature Name Property is Profile, then the lead-in type will be again set to Tangent. This will accommodate the scenario of needing a Tangent lead-in even when the IsClosed feature property is true. Browse to directory set in the KnowledgeBase Document Settings > Save File). If it was created using a text document, save the text document and re-open the VB Editor to expand the KBM Rule Evaluator; the new function should then appear. A final look at the new function appears below. Public Function LeadInSelect(Feature As Object) As Long Dim EF As Esprit.FeatureChain Set EF = Feature If EF.IsClosed = False Then Else LeadInSelect = 0 If EF.Name = Profile Then End Function In conclusion, this function is explained as such: If the feature is closed, use the Distance lead-in type. If not, use the Tangent lead-in type. However, regardless of whether the feature is open or closed, set the lead-in to Tangent if it has the Name Profile. The only thing left to do is to add the function to the lead-in technology field within a Contour Milling operation. If this function is to be used as a default, it can be added to the Default Technology using the ESPRIT KnowledgeBase. The function is called by inserting the name of the function and the Object into the Expression Builder as shown in Figure 6. Figure 6 If EF.Name = Profile Then The last step in preparing this function is to end the if statements (each one must be ended individually) and the function itself by inserting the code below. End Function At this point, it is necessary to save the function. If the function was created using in the VB Editor and a module, then export the module to the location set in the KnowledgeBase Document Settings (File > Export File > Take a minute to consider the possibilities now that this function has been created. One could create another function based on this one for the lead-out technology field. For example, my company uses this LeadInSelect function for the Lead-in field and a LeadOutSelect function for the lead-out field. The only difference between the two is that the LeadOutSelect function sets the lead-out to Distance if the feature name is Profile. 4

5 The lead-in/lead-out distances are then set based upon the tool being used and the feature to which the operation is being applied (refer to Part I for further explanation of this functionality). The conditions covered in these functions/ expressions accommodate 95 percent of the lead-in/lead-out types necessary for the type of machining that we do. ESPRIT s ability to maintain and deploy defaults allows for minimal time needed to apply a Contour Milling operation. This also provides our machine operators with consistency between programmers. Regardless of who writes the program, the machine operator can depend upon things like Clearances, Speeds and Feeds and Overcut Percentages to be the same. Instilling this confidence in our operators makes way for less dry running time and a better quality part. In closing, I d like to urge all my fellow ESPRIT users to take the time to sharpen the saw. The tools to do so have been brilliantly set before us; we need only pick them up and use them. Unlike other software I ve used, ESPRIT is truly a Windows-based software package. Baring this in mind, we are limited only by our imagination. There seems to be this notion that automation is only for Job Shop environments or family-of-parts programming. While these situations are perfect for automation, as well, there are areas within every shop that can be optimized. So, the next time you find yourself performing that perfunctory task over and over again, remember that using Visual Basic and the ESPRIT KnowledgeBase is not just for the gurus. It s for everyone, at any skill level and in any shop environment. DP Technology Corp. Phone: Avenida Acaso Outside the US: Camarillo, CA USA esprit@ ESPRIT is a registered trademark of DP Technology Corp DP Technology Corp. All rights reserved. 5