According to an embodiment, a disk storage apparatus includes a disk with a servo pattern recorded thereon and a processor. When a signaling message is received, it is determined whether the signaling message includes a routing indication indicating route-on-point-code-subsystem-number. The ground sense pin is connected to a ground port of the circuit. The ring electrode has a fixation device disposed within the ring electrode, and the fixation device forms an interference fit with the conductor member, forming an electrical contact therebetween.