Analog quantity input module of DCS

Abstract

The invention discloses an analog quantity input module of a DCS. The analog quantity input module comprises a power supply circuit, a CPU module, a communication circuit and a channel acquisition circuit, wherein the power supply circuit is used for supplying power to whole AI module, the channel acquisition circuit is used for transmitting onsite signals to the CPU module, the CPU module is used for communicating with a control station with the DCS through the communication circuit, the channel acquisition circuit is provided with a common-mode inhibition circuit with high input impedance and a common-code inhibition capability, and the common-mode inhibition circuit is used for performing differential mode amplification on the onsite signals and realizing common-mode inhibition at the same time. According to the invention, through the common-mode inhibition circuit with common-mode inhibition, amplification can be performed on a differential mode, a common mode is inhibited accordingly, and the problem of poor anti-common-code interference capability in an AI module in a conventional DCS is solved.

Description

technical field [0001] The invention relates to the field of DCS control systems, in particular to an analog input module of the DCS system. Background technique [0002] In the DCS control system, the use of AI analog input modules is very popular. In the field, it is often encountered that the common mode signal is coupled on the transmission signal line due to the poor site environment. When the common mode signal is relatively large, it will have a great impact on the signal, resulting in inaccurate signal detection. The current general method is to add a voltage follower amplifier to the input for signal acquisition, but the voltage follower amplifier cannot suppress the common mode signal, and because of its low input resistance and high requirements on the matching degree of the resistance ratio in the circuit , so the common-mode rejection capability is not very strong. Contents of the invention [0003] The purpose of the present invention is to address the defi...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to address the deficiencies in the prior art, to provide an analog input module of a DCS system, through the common mode suppression circuit of the present invention, only the differential mode can be amplified, and the common mode can be suppressed, so as to solve the problem of DCS system The problem that the anti-common-mode interference ability of the AI ​​module is not very strong

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