PLC Solutions for Industrial Noise Monitoring and Control

In industrial production, noise control directly relates to employee health and equipment lifespan. This article introduces a noise monitoring and control system solution based on the Siemens S7-1200, achieving fully automated noise monitoring and early warning control.

1. Hardware Configuration Scheme

PLC and Expansion Module Selection

• CPU: S7-1214C DC/DC/DC
• Analog Input Module: SM1231 4AI
• Analog Output Module: SM1232 2AO
• Digital Input Module: SM1221 8DI
• Digital Output Module: SM1222 8DO

I/O Point Allocation Table

Input Points:

%I0.0 - System Start Button

%I0.1 - System Stop Button

%I0.2 - Alarm Acknowledgment Button

%IW64 - Noise Sensor 1 Data

%IW66 - Noise Sensor 2 Data

%IW68 - Noise Sensor 3 Data


Output Points:

%Q0.0 - System Running Indicator

%Q0.1 - Alarm Indicator

%Q0.2 - Sound and Light Alarm

%QW80 - Soundproof Door Control

Peripheral Device Selection

• Noise Sensor: BSWA Sound Level Meter, measuring range 30-130dB
• Sound and Light Alarm: LED + Buzzer Combination
• Soundproof Door Actuator: Servo Motor Control
• Touch Screen: Siemens KTP700 Basic

2. Control Program Design

A. Variable Definition Specification

Global Variable Table (DB1):

NoiseValue[3]: REAL    // Noise Value Array

AlarmLimit: REAL       // Alarm Threshold

WarningLimit: REAL     // Warning Threshold

SystemStatus: INT      // System Status

AlarmStatus: BOOL      // Alarm Status

B. Program Architecture Design

System Initialization (OB100):

// System Parameter Initialization

AlarmLimit := 85.0;    // Alarm Threshold 85 Decibels

WarningLimit := 75.0;  // Warning Threshold 75 Decibels

SystemStatus := 0;     // System Initial Status

Main Control Program (OB1):

// Noise Data Acquisition and Processing

CALL "NoiseDataAcq" 

    Input := %IW64

    Output := NoiseValue[1]
    

// Noise Alarm Control

CALL "NoiseAlarmCtrl"

    NoiseValue := NoiseValue[1]

    AlarmLimit := AlarmLimit

    AlarmOut := %Q0.1

C. Function Block Design

Noise Data Acquisition FB (FB1):

FUNCTION_BLOCK "NoiseDataAcq"

VAR_INPUT

    Input : WORD;    // Sensor Raw Data

END_VAR

VAR_OUTPUT

    Output : REAL;   // Converted Decibel Value

END_VAR

VAR

    TempValue : REAL;

BEGIN

    // Data Conversion Formula

    TempValue := INT_TO_REAL(WORD_TO_INT(Input));

    Output := (TempValue / 27648.0) * 130.0;

END_FUNCTION_BLOCK

D. Data Storage Design

Parameter Configuration Data Block (DB10):

STRUCT

    SamplingTime : TIME := T#100MS;  // Sampling Cycle

    FilterCoef : REAL := 0.8;        // Filtering Coefficient

    RecordInterval : TIME := T#1H;   // Recording Interval

END_STRUCT

3. User Interface Design

Interface Layout

• Main Screen: Real-time Noise Curve, Current Value Display
• Parameter Settings: Threshold Settings, Sampling Cycle Adjustment
• Alarm Records: Alarm History, Acknowledgment Status
• Trend Analysis: Daily Report, Weekly Report Generation

4. System Debugging Plan

Step-by-Step Debugging

1. I/O Point Testing: Confirm Signals One by One
2. Data Acquisition Testing: Verify Data Accuracy
3. Control Logic Testing: Check Alarm Trigger
4. System Integration Testing: Full Process Function Verification

5. Experience Summary

System Optimization Suggestions

1. Use Moving Average Filtering to Eliminate Interference
2. Implement Remote Data Upload Functionality
3. Increase Predictive Maintenance Features
4. Optimize Alarm Strategy to Avoid False Alarms

If you have any questions about the content of this article, feel free to leave a message for discussion. Let’s explore the application and development of industrial automation technology together.