Programmable Logic Controllers are computer devices often used in industrial control systems as primary components that provide operational control and monitoring. The software running on these controllers is usually programmed in an Integrated Development Environment using a graphical or textual language defined in the IEC 61131-3 standard. Although traditionally, engineers have tested programmable logic controllers’ software manually, test automation is being adopted during development in various compliant development environments. However, recent studies indicate that choosing a suitable test automation framework is not trivial and hinders industrial applicability. In this paper, we tackle the problem of choosing a test automation framework for testing programmable logic controllers, by focusing on the COntroller DEvelopment SYStem (CODESYS) development environment. CODESYS is deemed popular for device-independent programming according to IEC 61131-3. We explore the CODESYS-supported test automation frameworks through a Grey Literature Review (GLR) and identify the essential criteria for choosing such a test automation framework. We validate these criteria with an industry practitioner and compare the resulting test automation frameworks in an industrial case study. Next, we summarize the steps for selecting a test automation framework and the identification of 29 different criteria for test automation framework evaluation. This study shows that CODESYS Test Manager and CoUnit are mentioned the most in the Grey literature review results. The industrial case study aims to increase the know-how in automated testing of programmable logic controllers and help other researchers and practitioners identify the right framework for test automation in an industrial context.