In the subject system for polarity detection, link initialization between a primary device and a secondary device may be performed in at least two stages, a half-duplex stage when only the primary device transmits initialization signals and any encoded handshaking signals may be set to false, and a full-duplex stage when both devices may transmit initialization signals. The gastrostomy feeding tube includes a coupling member, such as an elongate tract or thread, that is accessible about the second end thereof. A forward model of the SNAP is developed and used to test the approach on a simplified data simulation.