What is the difference between local instruments and primary instruments?
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The existing equipment requires the installation of local instruments and primary instruments. What is the difference between local instruments and primary instruments?
Local instruments are instruments installed at the site; they are generally used for on-site indication and do not send signals； Primary instruments are also instruments installed on-site; they are those that send signals to the control room, as well as actuators that receive signals from the control room (usually control valves, and control valves are also considered instruments).
Display only on-site; send signals to the control room once to receive instructions