Automated Verification Environment for TwinCAT PLC Programs

The European XFEL will have three undulator systems SASE1, SASE2, and SASE3 to produce extremely brilliant, ultra-short pulses of x-rays with wavelengths down to 0.1 nm. The undulator gap is adjustable in order to vary photon beam energy. The corresponding motion control is implemented with industrial PCs running Beckhoff TwinCAT Programmable Logic Controllers (PLCs). So far, the functionality of the PLC programs has been verified on system level with the final hardware. This is a time-consuming manual task, but may also damage the hardware in case of severe program failures. To improve the verification process of PLC programs, a test environment with simulated hardware has been set up. It uses a virtual machine to run the PLC program together with a verification program that simulates the behavior of the hardware. Test execution and result checking is automated with the help of scripts, which communicate with the verification program to stimulate the PLC program. Thus, functional verification of PLC programs is reduced to running a set of scripts, without the need to connect to real hardware and without manual effort