This paper presents the Hardware-in-the-loop (HIL) validation of a vertical stabilization algorithm for tokamak plasmas based on the Extremum Seeking (ES). This validation is performed by exploiting the rapid prototyping capabilities of the integrated software environment for the deployment of real-time systems based on MDSplus and MARTe2. Using a rapid prototyping tool, the code generated by Simulink Coder® is automatically wrapped into a module that is executed by the MARTe2 application running on a Linux host. HIL validation is then performed interfacing the real-time host with a plasma model executed on a SCALEXIO dSpace® target. The proposed setup is used to validate the ES-based plasma vertical stabilization algorithm in real time before the experimentation on the TCV tokamak. In particular, the maximum control delay that can be tolerated is also assessed.