COMMUNICATION ADAPTER

A communication adapter that can notify occurrence of power supply interruption to external management device in response to power supply interruption is provided. The communication adapter includes a power storage configured to receive power supply from an external device and store power, a communication unit configured to receive power supply from the power storage, and a control unit capable of communicating with an external management device via the communication unit. A capacity of the power storage for the control unit to communicate with the external management device has variable lower limit. Lower limit of the capacity of the power storage while the power storage is receiving power supply from the external device is first capacity value. Lower limit of the capacity of the power storage in a case of power supply to the power storage from the external device being interrupted is second capacity value lower than first capacity value.