What is FDM?
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What is FDM and what are its functions?
FDM is the abbreviation for Frequency Division Multiplexing. In Chinese, it is referred to as “频分多路复用”. It involves using different frequencies to transmit various messages, thereby enabling multiple simultaneous communications. This method is also called frequency reuse.
The last edit to this post was made by lsv on 2016-3-10 09:07. Field Device Manager is a system for managing field devices; it is equivalent to Emerson’s AMS. It is a software package that can be installed on its own server or shared with other servers. It collects HART signals from field smart devices such as transmitters and valve positioners via the DCS network, enabling the analysis and management of these field devices.
Your explanation seems correct. What is HART, and what are its functions? Can the information from all the instruments on site be transmitted to the engineer station?
The HART protocol is a standard communication protocol developed in 1986 by the American company Rosemount. Its full name is Highway Addressable Remote Transducer, which translates to an addressable highway for remote sensor data. In the sense of field buses, the HART protocol is characterized by an architecture similar to that of field buses, featuring bus-based digital communication; however, HART is not a true field bus ； It superimposes an FSK (Frequency Shift Keying) digital signal on the 4–20mA analog signal; this allows for both the transmission of the 4–20mA analog signal and digital communication, with the digital communication signal not affecting the transmission of the analog signal. The HART communication protocol is based on the \"ISO/OSI\" model standard, with layers 1, 2, and 7 of that standard being simplified and adopted ； The HART protocol uses FSK frequency-shift keying signals based on the Bell202 standard. It superimposes a sine modulation wave with an amplitude of 0.5mA on an analog signal ranging from 4 to 20mA; 1200Hz represents logic “1”, while 2200Hz represents logic “0”.
Thank you, the explanation was very clear; I need to study hard**