The hardware controllers accept standard instructions parsed from the test requirements, and execute them on the interface they are responsible for. The internal interface between the hardware controllers and the rest of the system is standardized; the hardware controller forms a module that isolates device-specific interface functions from the rest of the system design.

This reduces development cost, as many hardware interfaces can be developed in parallel with the rest of the system. It also reduces out-year maintenance of the design, as new devices with the same functions can be readily integrated without provoking a change in the configuration of the main software or the instructions.