Various connection detection assemblies for a robotic surgical assembly are disclosed. The robotic surgical assembly can include a carriage, a carriage housing releasably connectable to the carriage, a motor housing configured to house a motor pack for driving the surgical instrument, wherein the motor housing is releasable connectable to the carriage housing, and an interface module configured to releasably secure the robotic surgical assembly to the surgical instrument. The robotic surgical assembly can also include a series of interconnections defined by mating portions of the carriage, the carriage housing, the motor housing, and the interface module. A control circuit configured to detect a fully engaged configuration of the mating portions based on the interconnections.