Bi-Directional Capabilities Bi-Directional Instrument: An instrument that both sends and receives data. IP Address: Each instrument at your facility must have an IP address. An IP address is a string of four integer numbers between 0 and 255 separated by periods. Port: The location of the instrument to which you send data and from which you receive data. HL7 Inst ID: The instrument ID in HL7 messages that identifies the instrument. The ID is provided by the vendor. HL7 Unv Svc ID: The universal service ID for HL7 messages identifies the type of procedure the instrument performs when the instrument is capable of performing more than one procedure. HL7 Link: There is one unique HL7 link for each instrument.