Category Archives: management

Omron C20K, C28K, C40K, C60K Troubleshooting

The Omron C20K, C28K, C40K and C60K shoebox programmable logic controllers have been discontinued since March of 2002. These ‘K’ series PLCs were a popular controller and have been in installations for over 25 years. We will take a look at this PLC and review some troubleshooting techniques. Planning for the eventual fatal failure of the CPU will also be discussed. Continue Reading!

The 7 Essential Parts of a PLC System

When I was in school PLC’s were just in their infancy. We were taught that the PLC consisted of the central processing unit (CPU), analog and digital inputs and outputs. Everything was programmed with dedicated handheld devices and/or software devices on specialized hardware. We now have modern PLC systems that are capable of so much more. Let’s look at how we can now break up these modern PLC system into the seven essential components.

Inputs and Outputs (I/O)
Analog I/O
Specialty I/O
Programming Tools
Networking Continue Reading…

Horner XL4 Establishing Communication

We program the Horner XL4 OCS all-in-one controller by using Cscape. We will now use our Cscape software to establish communication. Last time we customized Cscape with icons to make it easier to find, communicate and control the unit. There are two different ways to communicate to the XL4 OCS controller, Ethernet and Serial. There are several different methods within these two ways that the XL4 will communicate. The Cscape software package will communicate both of these ways. We will look at establishing communication using Ethernet, USB (Serial) and Serial RS232.Another two serial ways to communicate would be RS485/RS422 (Serial) and CAN Bus (Serial). These two methods allow multiple controllers connected to the communication network. This is similar to Ethernet. Continue Reading!

Click PLC AdvancedHMI Communication

Advanced HMI is a powerful, adaptable HMI/SCADA (Supervisory Control and Data Acquisition) development package that takes advantage of Visual Studio. There is no coding required and you can simply drag and drop items onto the page. The best thing is that the software is free. We will look at using AdvancedHMI with the Click PLC. Our sample Click PLC program will read the present value (PV) and the indicating lights on our Solo Process Temperature Controller. It will then write the set value (SV) to the Solo. This communication will be done using Modbus RTU protocol over a RS485 serial port on the Click. The AdvancedHMI package will communicate Modbus TCP over Ethernet to the Click PLC. We will be able to monitor our PV and set our SV on the Solo via the AdvancedHMI window.  Keep on Reading!

Click PLC Drum Instruction

Drum instructions are great tools when you have a simple sequence of events that need to occur at a set time interval or as a result of an event. They mimic an electromechanically drum sequencer. The Click PLC has a drum in the instruction set. We will discuss the drum instruction and look at an example of controlling traffic lights.  Keep on Reading!

Understanding the PLC Program Scan

Understanding how the PLC will scan and update your program is critical in programming and troubleshooting your system. Typically a PLC will solve your logic from left to right, top to bottom. The status of the memory from the previous rung, are available for the next rung to use. We will look at a few examples to determine how the PLC will solve logic to illustrate the above program scanning.  Keep on Reading!

Click PLC Numbering System and Addressing

Continuing our series, we will now look at the numbering systems and addressing used in the Click PLC. Previously we have discussed:
Click PLC System Hardware
Click PLC Installing the Software
Click PLC Establish Communication
The programming software and manuals can be downloaded from the Automation Direct website free of charge. These are being used exclusively in our Click PLC series.  Keep on Reading!

Deploying an AdvancedHMI Project

Deploying an AdvancedHMI project on the industrial floor sounds like an easy task, but there are a few things that you should consider. The HMI (Human Machine Interface) user interface will run on a computer. The industrial environment is one in which temperature, dust, electrical noise, etc. are always present. This can also be combined with workers wanting to play with the new computer. We will look briefly at the hardware and software items that will make your install more reliable and user friendly in the field.

The hardware that you deploy in the field should match the environment that you expect it to work in. Computers come in many shapes, sizes and price points. Here are a few items that you may want to consider.

  • Fanless Computer – This will keep the dust out but temperature may be a problem.
  • Monitor – Location and type – Do you need touch screen?
    Keyboard and mouse – Washable?
  • Enclosures – If you are in a wash down environment then an enclosure is a necessity. Sometimes these enclosures are worth more than the contents in them.
  • UPS – The uninterruptable power supply will usually serve two purposes. It will act when power is removed so the computer will be able to shutdown correctly. The UPS will usually also act as a power conditioner. Most power has surges on the line and this can be amplified when in the industrial environment. The surge suppressors in the UPS will protect the computer.
  • Program backup – Have multiple copies of the software saved in different places. You never know when the unexpected will happen. (Fire / Thief etc.) This includes the backup disks for your operating system as well as the programs (versions) that you are running on the computer. (AdvancedHMI, Visual Studio)
  • Documentation of the backup (Hardware / Software) – Ensure that you have documentation of the hardware and software versions that you are using. I would also include where everything was purchased. This way if records are missing we can track this down through the supplier.

The software that we have on the production floor should be robust. This means that we should know what happens if thing go wrong. Backups as mentioned above should happen on a regular basis. Memory is inexpensive so backup your files regularly. We usually use a networked computer to automatically back up the production files each day. The following is a list of items that you should pay attention to when deploying a computer on the production environment.

  • Turn off windows update – Windows is great at keeping itself up to date. However this can cause programs to stop working. When dealing with an AdvancedHMI deployment we set windows to ‘Download updates but let me choose whether to install them’. It can take several minutes for windows to update. You want to be sure that the machine being controlled will not be affected.
  • Security – Set permissions – When setting up your windows computer for the factory floor, do not give the account that boots up and logs on automatically Administrator Privileges. It should be set up as a Standard User. This will prevent unauthorized software being loaded onto the system.
    Internet Explorer comes standard on any new computer with windows 8.1 or older. No other browser is present out of the box. It is good to set a supervisor password on the internet connection. This will allow you to restrict the internet use.
    On the run prompt type: RunDll32.exe msrating.dll,RatingSetupUI
    Goto the General tab to select a supervisor password
  • AdvancedHMI – There are a few thing that we can do in the AdvancedHMI project. We will look at the AdvancedHMI project that we did for Creating a HMI Login Screen on AdvancedHMI.

    o ControlBox – Remove the ControlBox on the main screen form. This will ensure that the user cannot minimize, maximize or close the application.

    o Maximize for screen size – Make the main screen form maximized so it will fill the entire screen.

    o Form.TopMost = True – This command will ensure that your application will be on top of all other windows forms.

    In this example the calculator has focus, but the our windows form will always be on top.

    If you have only one form then you can use the Properties settings for the form you always want on top. Multiple pages will have to include some additional programming to ensure that they are on top and visible.
    Here is the code for the returning to the main form of the program.
Private Sub ReturnToMainButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCancel.Click
    Me.TopMost = False
    MainForm.TopMost = True
End Sub
  • Shortcut on the desktop – Place a shortcut to the AdvancedHMI application on the desktop. This will allow someone to quickly start the application if the application unexpectedly closes.

Following the above recommendations will ensure that your computer will perform and last as expected on the factory floor. Your AdvancedHMI project will work reliable and efficiently.

If you would like a copy of the PLC and AdvancedHMI programs, please contact me and I would be happy to send them to you.

Watch on YouTube : Deploying an AdvancedHMI Project
If you have any questions or need further information please contact me.
Thank you,

Archie Jacobs from Manufacturing Automation, LLC  has another tip for disabling the windows error recovery on startup.
On the PC that will run AdvancedHMI, click the start button and type CMD to find the Command Prompt. Right Click on the command prompt and select Run As Administrator
Once the Command Prompt opens, type the following:
bcdedit /set {current} bootstatuspolicy ignoreallfailures
This will prevent problematic startup when the PC is not shut down properly as often happens in the industrial environment.

If you’re like most of my readers, you’re committed to learning about technology. Numbering systems used in PLC’s are not difficult to learn and understand. We will walk through the numbering systems used in PLCs. This includes Bits, Decimal, Hexadecimal, ASCII and Floating Point.

To get this free article, subscribe to my free email newsletter.

Use the information to inform other people how numbering systems work. Sign up now.

The ‘Robust Data Logging for Free’ eBook is also available as a free download. The link is included when you subscribe to ACC Automation.

Modbus TCP Data Logging to Database

Using Visual Basic 2015 we will log three holding registers from the PLC along with time and date into a Microsoft Access Database. We will log every minute into the database with the information that we collect from the PLC via Modbus TCP (Ethernet). All code will be done and shown so you can implement this in your application with different parameters. The information collected in the database can then be distributed or analyzed in the future.

Visual Basic 2015 will be used with the EasyModbusTCP client/server library for .net. We will communicate to an Automation Direct – Do-More PLC. Using the free simulation software of the PLC Designer Software, we will retrieve three values of the Modbus Holding Registers using Modbus TCP. Once we have this information out of the programmable logic controller it will be placed in a Microsoft Access (2010) Database. This will be done by using a SQL command to insert the data.

Automation Direct has a powerful simulator with their Do-More PLC. The PLC software is available from Automation Direct as a free download.

We will start with the PLC program. The first  three holding registers will be used. That will be MHR1, MHR2 and MHR3 in the Do-More PLC. This will correspond to register numbers 40001, 40002 and 40003. The following is a table with all of the references for Modbus communications to the Do-More.

Coil/Register Numbers Data Addresses Type Do-More PLC Table Name
00001-09999 0000 to 270E Read-Write MC1 to MC1023 Discrete Output Coils
10001-19999 0000 to 270E Read-Only MI1 to MI1023 Discrete Input Contacts
30001-39999 0000 to 270E Read-Only MIR1 to MIR2047 Analog Input Registers
40001-49999 0000 to 270E Read-Write MHR1 to MHR2047 Analog Output Holding Registers

Note: The Do More PLC uses the Modbus area to communicate. This is because having direct access to the digital I/O can be dangerous when connected via Ethernet to the internet. Data must move in and out of this area via the PLC program.

Here is the PLC program that sets the three registers.

The next thing to do is set up our Microsoft Access 2010 Database. Our database will be named ACC_Database and it will be located at the following location: “C:\AccLog”. We will have one table called ACC_Log. In the table we will have five fields; LogDate, LogTime, Register1, Register2, Register3.

Visual Basic 2015 is free and is part of Visual Studio 2015. It can be downloaded at the following location:

EasyModbusTCP is free software. It will be referenced in our visual basic program.  It can be downloaded from the following location:
After downloading you must extract the files.

EasyModbusTCP is a Modbus TCP, Modbus UDP client/server library for .NET and Client library for JAVA. .NET (.dll) Client/Server also supports Modbus RTU. It supports the following function codes: – Read Coils (FC1)
– Read Discrete Inputs (FC2)
– Read Holding Registers (FC3)
– Read Input Registers (FC4)
– Write Single Coil (FC5)
– Write Single Register (FC6)
– Write Multiple Coils (FC15)
– Write Multiple Registers (FC16)
– Read/Write Multiple Registers (FC23)

Now we will call up visual studio and create our project. The first thing that we must do is reference our EasyModbus.dll file.

Our program will log the three registers based upon a timer function. When the time expires we will set the interval to 1 minute and call a subroutine (Button1). This subroutine will communicate to the PLC via Modbus TCP and get our three registers. It will then insert the data from the registers along with the time and date into an access database.

Here is what our visual basic form will look like:

Here is the visual basic code for our project. We use the Imports command for the EasyModbusTCP namespacing.

Imports EasyModbus 'Import the EasyModbus 

Here is the part of the subroutine that will communicate to the PLC via the EasyModbusTCP, You will notice that we have used the ‘Try’ command on the ModbusClient.Connect() statement. This way we can track if we are communicating or not to the PLC.

Public Class Form1
  Private Sub Button1_Click() Handles Button1.Click
 'This subroutine will communicate using the EasyModbusTCP to the PLC
 'This will execute when the user clicks the button or at specific intervals from the Timer1
 Dim ComError = 0 'Set communication error flag to 0
 'Specify the IP Address and Port Number that we are connecting
 Dim ModbusClient As EasyModbus.ModbusClient = New EasyModbus.ModbusClient(TextBox1.Text, 502)
 ModbusClient.Connect() 'Connect to the PLC
 Catch ex As Exception 'What to do when an error occurs
 Label10.ForeColor = Color.Red
 Label10.Text = "Communication Error!"
 ComError = 1 'Set communication error flag to 1
 End Try
 If ComError = 0 Then 'Do the following when communication is OK
 Label10.ForeColor = Color.Black
 Label10.Text = "Logging..."
 Dim Registers As Integer() 'Where to store the information
 Registers = ModbusClient.ReadHoldingRegisters(0, 3) 'Read three registers starting at the first one
 Label1.Text = Registers(0) 'Value of MHR1
 Label2.Text = Registers(1) 'Value of MHR2
 Label3.Text = Registers(2) 'Value of MHR3
 ModbusClient.Disconnect() 'Disconnect from the PLC

Here is the code to open the database connection and insert the data into our ACC_Database file. We use the ‘Try’ command to ensure that if errors occur it will not stop our program. The connection string ( Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\AccLog\ACC_Database.accdb) may be different then yours. In order to get your connection string, please review the following from a previous post and search for connection string.

'Log values into an Access Database
 'We will use a SQL instruction to insert a record into the table
 Dim SQL As String 'SQL Command String
 Dim objCmd As New OleDb.OleDbCommand 'Command
 'Connection String to the Access Database
 Dim Con = New OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\AccLog\ACC_Database.accdb")
 'SQL Statement - All values must be set for the table
 SQL = "INSERT INTO ACC_Log VALUES ('" & Now.ToString("yyyy/MM/dd") & "', '" & Now.ToString("hh:mm:ss") & "', '" & Registers(0) & "', '" & Registers(1) & "', '" & Registers(2) & "')"
 Con.Open() 'Open the database connection
 objCmd = New OleDb.OleDbCommand(SQL, Con) 'Set the command
 objCmd.ExecuteNonQuery() 'Execute the SQL command
 Con.Close() 'Close the database connection
 Catch ex As Exception 'What to do when an error occurs
 Label10.ForeColor = Color.Red
 Label10.Text = "Database Error!"
 End Try
 End If
 End Sub

This timer is originally set for 100ms. When the program starts, it will log the first time and then set the timer interval to 1 minute. (60000ms)

 Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
   Label9.Text = Now 'Display time and date
 Timer1.Interval = 60000 'Set interval for 1 minute
 Timer1.Enabled = True
 Call Sub() Button1_Click() 'Call the routine to get the PLC information and store in a database
 End Sub

This will handle the LinkLabel on the form.

 Private Sub LinkLabel1_LinkClicked(sender As Object, e As LinkLabelLinkClickedEventArgs) Handles LinkLabel1.LinkClicked
   ' Specify that the link was visited.
 Me.LinkLabel1.LinkVisited = True
 ' Navigate to a URL.
 End Sub
 End Class

Running the program:
The status will show ‘Initializing..’ so that the imports can be loading in the program. This will happen each time the software starts.

Logging will be displayed in the status to indicate that everything is working correctly.

Error messages will show in the status when an error has occurred. We have programmed two errors:
Communication Error! – Information is not being received from the PLC. This could be due to the wrong IP address or communications links have been broken.
Database Error! – Information cannot be written into the database, the database is not present, etc.

Here is what our database looks like after collecting a few samples.

As you can see, collecting information from the PLC via ModbusTCP and inserting it into an Access database can be easily done. The next steps would be to ensure that the data is always collected. What happens when the communication to the PLC is cut? Robust logging is required. This is when we create a buffer in the PLC of the logged values. Please refer to our EBook ‘Robust Data Logging for Free’ .

Download the sample database, visual basic and PLC code for this project here.

Watch on YouTube : Modbus TCP Data Logging to Database
If you have any questions or need further information please contact me.
Thank you,

If you’re like most of my readers, you’re committed to learning about technology. Numbering systems used in PLC’s are not difficult to learn and understand. We will walk through the numbering systems used in PLCs. This includes Bits, Decimal, Hexadecimal, ASCII and Floating Point.

To get this free article, subscribe to my free email newsletter.

Use the information to inform other people how numbering systems work. Sign up now.

The ‘Robust Data Logging for Free’ eBook is also available as a free download. The link is included when you subscribe to ACC Automation.