09-07-2011, 03:37 PM
One of the problems of instrumentation systems is the interconnection between the multiple devices with different protocols. Minimizing the cabling cost and avoid degradation of the signal during transmission are the two typical requirements of the interconnection. Another problem in the field of manufacturing is instrumentation with different communication protocols. This seminar presents the development of a HART communication prototype for instrumentation networks. For many years, the field communication standard for process automation equipment has been a milliamp (mA) analog current signal. The milliamp current signal varies within a range of 4-2OmA in proportion to the process variable being represented. Li typical applications a signal of 4mA will correspond to the lower limit (0%) of the calibrated range and 2OmA will correspond to the upper limit (100%) of the calibrated range. Virtually all installed systems use this international standard for communicating process variable information between process automation equipment.HART Field Communications Protocol extends this 4- 2OmA standard to enhance communication with smart field instruments. The HART protocol was designed specifically for use with intelligent measurement and control instruments which traditionally communicate using 4-2OmA analog signals. HART preserves the 4- signal and enables two way digital communications to occur without disturbing the integrity of the 4-2OmA signal. Unlike other digital communication technologies, the HART protocol maintains compatibility with existing 4-2OmA systems, and in doing so, provides users with a uniquely backward compatible solution. HART Communication Protocol is well-established as the existing industry standard for digitally enhanced 4- 2OmA field communication.
