Romilly's HART® and Fieldbus Message Board
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HART signal acceptance
Message posted by Fred Zhang (z_jd@hotmail.com : 216.220.44.141) on 03 November 2005 at 16:33:46.
I am confused with the mechanism of HART bidirectioal communication signal. If we have a DCS system with the HART field instrument (both valve and transmitter), during the configuration of instruments, the communication is 2-way, is it by the way of voltage signal instead of current since the field instrument is not supposed to work and there is no analog current value (>=4mA)existing in the loop? If the instrument is working and DCS is receiving the diagnostic message from the field by HART, which signal is used by telegram sender and receiver, voltage or the current,or both?
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