A simple PLC motion control project

Automation industry , It's getting closer to the software industry .

quite a lot PLC Engineers are beginning to realize , Master a programming language , Becoming more and more important .

that PLC After engineers learn to program , What kind of experience will it be ？

I think the most direct experience is ： Know more about principled things , The technology stack is more comprehensive , Can complete the project evaluation independently 、 drawing 、 The selection 、PLC Program development and debugging , To the upper computer development , Even higher WEB End 、 Mobile .

Get down to business , This paper mainly shares a motion control case commonly used in industrial field , From hardware selection to program design , Then from local debugging to host computer development and debugging .

This case is a relatively simple case , But it can effectively PLC Combined with the upper computer , For beginners , It is a more suitable hand training project .

1、 Hardware selection

controller ： Siemens 200Smart PLC, Models for ST20（DC-DC-DC）

Driver ： Stepping driver

The motor ：42mm Stepper motor

Limit ：3 A limit switch , Corresponding to the origin respectively 、 Left limit 、 Right limit

platform ： Uniaxial module

Button indicator ： start-up 、 stop it 、 Running state 、3 A travel switch （ Analog completion signal ）

2、 Hardware wiring diagram

3、PLC Application development

S7-200 Smart PLC Motion control requires the use of a motion control wizard , The core procedure is as follows ：

4、 PC program development

（1）I/O surface ：PLC Program programming , The host computer interface will be reserved , Upper computer I/O The table is shown below ：

（2） Interface design ： Upper computer UI Interface design

（3） Function realization ： The upper computer mainly includes real-time status and data monitoring 、 Speed and position parameter setting 、 The system log shows 、 Communication parameter settings .

• Real time status and data monitoring

This case is similar to Siemens PLC The communication mode between is S7 signal communication , Use open source communication library s7.net To achieve , Real time data acquisition based on multithreading , Combined with practice I/O Data analysis .

        private void PLCCommunication()
        {
            while (!cts.IsCancellationRequested)
            {
                byte[] result = plc.ReadBytes(StoreType.DataBlock, 1, 0, 23);

                if (result != null && result.Length == 23)
                {
                    this.Invoke(new Action(() =>
                    {
                        // Real time status update here 
                    }));

                    Thread.Sleep(10);
                }
            }
        }

• Speed and position parameter setting

Independent setting interface is adopted for parameter setting , Pass values through the form to realize .

The code is as follows ：

        /// <summary>
        ///  The set value 
        /// </summary>
        public string setValue = string.Empty;
        private void btn_Set_Click(object sender, EventArgs e)
        {
            this.setValue = this.txt_SetValue.Text;
            this.DialogResult = DialogResult.OK;
            this.Close();
        }

• The system log shows

The system log is based on ListView Control development , Implementation log 、 Call the police 、 The warning is displayed differently in three different states , It can be stored in the database at the same time , Facilitate subsequent traceability .

        private string CurrentTime
        {
            get { return DateTime.Now.ToString("HH:mm:ss"); }
        }
        // Write to the log 
        private void AddLog(int index, string log)
        {
            if (this.lstInfo.InvokeRequired)
            {
                this.lstInfo.Invoke(new Action(() =>
                {
                    ListViewItem lst = new ListViewItem(CurrentTime, index);
                    lst.SubItems.Add(log);
                    this.lstInfo.Items.Insert(0, lst);
                }));
            }
            else
            {
                ListViewItem lst = new ListViewItem(CurrentTime, index);
                lst.SubItems.Add(log);
                this.lstInfo.Items.Insert(0, lst);
            }
        }

• Communication parameter settings

Communication parameters are system parameters , use Winform Of Settings To configure storage , Simple and quick .

The interface design is as follows ：

The code is as follows ：

        public SaveDefaultSettingDelegate SaveDefaultSetting;
        private void btn_Set_Click(object sender, EventArgs e)
        {
            CommSet set = new CommSet();
            try
            {
                set.IPAddress = this.txt_IPAddress.Text;
                set.CPUType = this.cmb_CPUType.Text;
                set.StoreTime = Convert.ToInt32(this.txt_StoreTime.Text);
                set.AutoStore = this.chk_AutoStore.Checked;
            }
            catch (Exception)
            {
                MessageBox.Show(" Please check whether the data format is correct "," Format error ");
                return;
            }
            SaveDefaultSetting(set);
            MessageBox.Show(" Configuration is successful , Immediate effect ", " Configuration is successful ");
            this.Close();                                                  
        }

5、 Written in the back

In recent years , As more and more devices begin to join IIoT The Internet （Industrial Internet of Things, Industrial Internet of things is short for IIoT）,IT And OT The boundaries between them will gradually disappear , Until it becomes one or the same system .

therefore , More and more electrical engineers begin to transform to PC development . Because on the basis of existing electrical skills , If you master the upper computer development skills , The salary reaches 20K, even to the extent that 30K, It's going to be easier .

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