This document discusses, among other things, n implantable device comprising a communication circuit configured to communicate with an external device, a logic circuit communicatively coupled to the communication circuit, and a processor, communicatively coupled to the logic circuit and the communication circuit. The processor is configured to communicate information with the external device, via the communication circuit and the logic circuit, using a set of communication messages. While in a device safety mode, the processor is held in an inactive state and the logic circuit is configured to communicate with the external device using a subset of the set of communication messages.