Code completion is a very important feature of modern integrated development environments. Research has been done for years to improve code completion systems for general-purpose languages. However, only little literature can be found for (AI-based) code completion for domain specific languages (DSLs). A DSL is a special-purpose programming language tailored for a specific application domain. In this paper, we investigate whether state-of-the-art code completion approaches can also be applied for DSLs. This is demonstrated using the domain-specific language TTI. TTI is used in transformer construction in an industrial context, where an existing code completion shall be replaced by an advanced machine learning approach. For this purpose, implementations of two code completion systems are adapted to our needs. One of them shows very promising results and achieves a top-5 accuracy of 95 percent. To evaluate the practical applicability, the approach is integrated into the existing editor of a power transformer manufacturer.