The CAN-I/O bus devices are designed with a modular approach in mind: One bus logic board attaches to the HA-CAN bus, manages the bus communications and handles the logical decisions required for changing actor state or reading sensor state information.
A separate controller or sensor module is then responsible for interaction
with the external actors or sensors, and isolates the HA system from the
electrical infrastructure outside of it.
This forms an additional layer of safety, together with the commercially sourced devices that are exclusively used when interaction with AC line voltages is required.
The form factor of the modules, connector placement, and interface between bus logic board and controller/sensor boards is standardized and defined in HA-I11.
The firmware running on the bus logic board is HA-P05.