These input/output expansion modules are designed for use with KMC BAC-5900 series controllers. Multiple CAN-5901s can be connected to a controller via a CAN bus. Each CAN-5901 supports up to eight universal inputs and eight universal outputs. For example, a BAC-5901 with four connected CAN-5901s could access up to (internal and external) 40 inputs and 40 outputs connected via terminal blocks.