Sensor Time Stamping for Mixed IEEE 1451 Network Protocols

Many applications require that the precise time at which a sensor reading is taken be known. However, time correlation of data obtained from sensors which are distributed over a network or several networks are subject to errors or misinterpretation because different time stamp formats are used, the clocks used for the timestamp may be inaccurate and there may be uncompensated delays in the network data transmission. We propose to provide a precise time stamp which would be built into, or easily added to, all networks which use the IEEE 1451 smart transducer format. It would have time resolutions ranging from microseconds to seconds and not necessarily rely on the Internet or Ethernet network for time synchronization. NIST-based radio time clocks and features of the IEEE 1588 synchronization standard will be used to implement the reliable timing. The Phase I prototype will consist of an Internet type NCAP and two IEEE 1451.2 (RS232) TIMs with an actuator and sensors.