This presentation provides a guide to fully utilize the two main operational modes of the DSSC engine, namely the Parallel Mode and the Serial Mode. These modes are selected based on the specific requirements of the Device Under Test (DUT) and are crucial for optimizing test efficiency and performance. In Parallel Mode, each channel of the engine is read per vector step. This is suitable when there is a need to read multiple channels simultaneously. On the other hand, in Serial Mode, the DSSC reads only one bit per vector step, reducing the DSSC readback time for a DUT with a single serial output pin. Notably, due to the limitations of the DSSC engine, even for device pins with serial communication, selecting Parallel Mode can be more beneficial for multi-site usage. The presentation will discuss the characteristics, advantages, limitations, and test times of these modes. It will also discuss how to appropriately select and apply these modes to optimize test strategies.