All posts by garrys

Here is a Method That is Helping PLC Programmers to Program Faster

PLC programming involves both direct and indirect addressing. Direct address programming involves writing each ladder logic rung to do the operation required. We often forget about using the powerful indirect addressing to solve our logic.

The below animated picture will show a simple example of using indirect addressing. This will use the MOVE instruction and transfer a word indirectly to output word V100. V[V0] means that the value in V0 will point to the V memory to get the value to move. You can think of this as a pointer for the memory location to move.

Indirect Addressing Animation

Of course we need to monitor V0. Our values are in sequence from V1 to V6. We need to ensure that V0 is always in the range from 1 to 6.

Lets take a look at a program sample using the Do-more Designer Software. We will set up the sequence similar to the animation above, but expand the program.
Just like above we will set up the pointer at V0 and the output at V100 memory locations. V1 to V37 will hold our output data sequence. This is outputs that we want to set on each event and/or time frame. You can see some of the registers and the corresponding values. These are set as a hexadecimal value. The following link will provide a review of the numbering systems in the PLC. (WHAT EVERYBODY OUGHT TO KNOW ABOUT PLC (PROGRAMMABLE LOGIC CONTROLLER) NUMBERING SYSTEMS)

Indirect Addressing 4 Data

This is the logic to set up the move instruction. The source is V[V0] which means the pointer is V0 in this memory area. The destination will be V100.

Indirect Addressing 1 MOV

An internal timing bit ST5($100ms) is used to increment the pointer V0. This could also be done by an event or series of events. The pointer is then compared to ensure that it is between 1 and 37.

Indirect Addressing 2 Pointer

Finally the output word is then transferred to the physical outputs. This is done by using the MAPIO instruction. Each bit can be set independently.

This example uses indirect addressing to program a sequence based upon time. We could just as easily used indirect addressing to compare inputs to a table and set the outputs accordingly. You can see how this method can greatly reduce the amount of time to develop your program. This holds especially true if the sequence needs to be changed. It would be just a matter of changing data values in the table.

The following are separate posts that use indirect addressing:

Building a PLC Program You Can Be Proud Of – Part 1
This use the control of an intersection traffic light to demonstrate direct versus indirect addressing.

Building a PLC Program That You Can Be Proud Of – Part 2
A sample program to control valves. This uses indirect addressing for the inputs as well as the outputs.

Now You Can Have Robust Data Logging for Free – Part 1
Using indirect addressing, this sample program will log information in the PLC to be retrieved at a later time.

Indirect addressing is a powerful method of programming to simplify and program faster than you ever thought possible. You can even use indirect addressing in the PLC to scale a non-linear analog input signal. Let me know you thoughts on using indirect addressing. What can you come up with?

Watch on YouTube : Here is a Method That is Helping PLC Programmers to Program Faster

If you have any questions or need further information please contact me.
Thank you,
Garry



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.

The Secret of Using Counters

funny_counter

Counters  are used in the majority of PLC programs. This is especially true if part of your SCADA system. Counters like the animated picture above count things. In this situation we are counting the number of turns the little guy makes. The counter is displaying the total number. This is considered a totalizing counter. If an output turned on to do something then it would be a preset (target number entered for the count) counter. There are also a wide variety of off the shelf industrial counters that you can use. The implementation of counters can be vast, however it all starts with a TIMING CHART. This is the same as the timing charts we discussed in ‘The Secret of Timers’ post.

A timing chart is the secret behind understanding of the counter that you need in your application. Making a timing chart before writing the program will ensure that all of the information will be accounted.

The timing chart is mapped out on a x and y plain. The ‘y’ plain has the state of the input on/off (1 or 0). The ‘x’ plain will show time.

The following shows a timing chart for a counter:
timing chart counterAs you can see in this timing chart, you have an input, output and display.

Inputs:
Inputs are used usually sensors that are wired to the counter (PLC) to indicate the items that we need to count. They can be switches, photoelectric sensors, proximity sensors, encoders, etc. (Wiring of NPN / PNP devices) A counter will generally have only one input. In the case of an encoder input it is still only one input, however this is wired usually as a A, B and Z phase. Z is always the reset. A and B indicate the pulses and are leading or trailing each other by 90 degrees depending on direction. Allot of counters will also allow you to as a direction input signal. However this is all still only one input.
Output ModesInput Modes

Outputs:
Outputs from counters are generally discrete. This means that they are on or off, similar to the inputs. Outputs will trigger when the count value matches the set value. The duration that the output is on depends on the reset signal, to start the count again. (DC Solenoids protection) Allot of the counters today will allow you to have multiple outputs. These multifunction counters can have several preset outputs that trigger when the counter set value has been reached. Batch outputs are also available on some of the industrial counters. A batch output counts the number of times that the preset has been reached. This output will be turned on when the number entered for the batch has been reached.

Set Value – SV:
This is usually on the display and shows the preset value. It is the target number of counts.

Present Value – PV:
This is usually on the display and shows the current or accumulated value.

Roller Measurment

The PLC programming is usually not that much different then the industrial counter. Allot of the manufactures will have an up counter, down counter and/or an up/down counter. Just as the name implies the display is either counting up or down. You have to refer to the instruction manual of the manufacturer you are programming for the way in which the counter will be programmed.

Do-More Up and Down Counter

In the above example Do-More PLC program we have an up and a down counter. X0 is the input and X1 is the reset on both of these counters. (CT0, CT1)
The preset value is stored in memory location D0. This value is set to the number 3.
When the present value (accumulated) reaches the set value (preset) then the CT0.Done bit goes on and the output Y0 is active. Y0 will remain on until the reset input goes on.
The only difference for down counter is the display. You will see that the present value will count down to zero (0) before the CT1.Done bit is turned on.
These counters are memory retentive. So in order to make the counter non-memory retentive, use the first scan bit of the PLC to trigger the reset of the counter. (ST0 – $FirstScan)

Every PLC has counters. They all have different types depending on what you are trying to achieve. It will all start with your Timing Chart.

Watch on YouTube : Learn PLC Programming – Free 9 – The Secret of Counters

If you have any questions or need further information please contact me.
Thank you,
Garry



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.

Looking For Production Improvements – Then Do A Gemba Walk!

I recently went for a Gemba Walk with Ann Machan,  General Manager of Pentair. Instead of doing normal daily production meetings, their walk does everything you can do in a boardroom, plus so much more.

What is a Gemba Walk?
http://www.gembawalk.com/the-gemba-walk/

We met in her office and were explained the KPI (Key Performance Indicators) for the operation of the plant.  Each of these KPI’s are posted at each department where the work happens and are on a large white board.

The walk each morning starts at the shipping office with the rest of the staff. The operator in shipping  discusses how their department has done in the last 24 hours in relation to the KPI. Questions are raised about the next 24 hours and possible issues. Before we leave this department Ann asks a few personal questions to the shipper. He answers and they start to laugh. It is obvious that they have a good relationship in which information can flow freely.

Splitting up the group into three different teams to cover the entire plant, the walk continues. We went to three additional departments where again we were shown the KPIs and how they related to the department. Notes were taken and questions asked about possible issues and current problems. Information was exchanged from the previous days problem with the solution for one that was to be implemented that afternoon.footprints

We assembled back all together in a central location in the plant. A large board with people’s names (Responsible for Department) was listed on the left side and twenty one numbers were written on the top representing three weeks. The current week that they were on, followed by the next two weeks. This grid pattern was where they then discussed the walk and the issues raised. To the right of the board a chart was placed. This chart contained the total number of problems/issues solved for each department and total company. A graph was also displayed showing the growing trend. Underneath this chart were the KPI charts that all showed either sustained or improved performance.

We started with the previous days issues under yesterdays date. A status update was given and the posted note was moved to either the completion clip at the side or put under a future date. When this was complete, a representative of each of the three groups when through their list of issues. These were then assigned and placed on the board. Problems that required additional investigation were discussed briefly and then the 5 why process was assigned to the person who had the greatest knowledge.

This whole process took about one hour. The Gemba walk accomplished the following:

  • Everyone’s understanding on the current company situation based upon the KPIs
  • Everyone knowing exactly what is expected
  • Everyone taking pride and knowing they are doing a good job
  • Everyone knowing someone is there to help

I found the whole experience of the Gemba walk fascinating. It is the only way that I see that you can have clear lines of communication to all staff. The way in which to grow as a company is to learn from our workers and in turn we will teach them.  It was an opportunity to:

  • See the work being done
  • Experiment with ideas
  • Learn from all parties involved
  • Explain why things are this / that way
  • Watch what is being done

Take your own Gemba walk on your production floor. Let me know how it turns out.

If you have any questions or need further information please contact me.
Thank you,
Garry



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.

The Secret of Using Timers

Timers are used in the majority of PLC programs. There are also a wide variety of off the shelf industrial timers that you can use. The implementation of timers can be vast, however it all starts with a TIMING CHART.

A timing chart is the secret behind understanding of the timer that you need in your application. Making a timing chart before writing the program will ensure that all of the information will be accounted.

The timing chart is mapped out on a x and y plain. The ‘y’ plain has the state of the input on/off (1 or 0). The ‘x’ plain will show time.

Lets take a look at a timing chart for an On-Delay Timer. This is the basic operation for an Omron H3BR industrial timer.

Timing Chart On-Delay Basic

Power –  When dealing with PLC’s we must consider when power to the unit is removed what happens to the current time and output conditions.
Start – In this case the start signal is momentary to start the time cycle. (t) We could modify this signal to be maintained until the output switches.
Output – The output will show when it turns on. This can also indicate the opposite, and show when it turns off.
Time – Time is shown by the relationship between the start signal and the output. Our example shows timing starts on the leading edge of the Start. This could have also been on the trailing edge.

Here is the same on-delay timing chart with some more detail. Several conditions are added to the chart.

Timing Chart On-Delay Details

These conditions prompt us to ask the following questions.
What happens when:

  • Power is removed / restored
  • Multiple start signals are received
  • Do we need a Reset signal. If so what happens during its operation
  • Do we need a display of the time. Present Value (PV) / Set Value (SV)

As you can see the timing chart is vital in determining how the sequence will be performed. This is the exact same method that I use when determining timing sequences in a PLC program.

Lets look at an example.

Motor_Sequence

When we hit the start button, the warning light then comes on. After a fixed time the warning light goes off and the motor starts. The motor will run until the stop button is hit.

We will start by using the Start / Stop Circuit we did earlier.

Timer Program

You will notice that we have added an internal memory bit (C0) as our Start Sequence. This is a memory retentive bit, so we can use the (ST0) $FirstScan to make this circuit non-memory retentive. If power goes off, or the PLC is put into program mode the circuit does not remember the last state. It will default to be off.
The sequence is as follows:

  • Start pressed
  • TMR starts to time (10seconds)
  • Warning output comes on
  • After TMR (10seconds)
    • Warning output goes off
    • Motor output comes on
  • Stop pressed
    • TMR is reset to 0
    • Warning light off
    • Motor is off

Every PLC has timers. They all have different types depending on what you are trying to achieve. It will all start with your Timing Chart.

Watch on YouTube : Learn PLC Programming – Free 8 – The Secret of Timers

If you have any questions or need further information please contact me.
Thank you,
Garry



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.

Lubrication basics

I recently went to a seminar on lubrication basics. This was presented by Mike Deckert of Flo Components Ltd.

So why talk about lubrication on a industrial automation website? Lubrication is vital in maintaining uptime on equipment. It is often thought of near the end of most automation projects, but it should be a principle component of all projects. If a piece of equipment moves, it will probably need lubrication. We often talk about MTBF (Mean Time Before Failure) on equipment. MTBF will be very low if lubrication is neglected.

In a study conducted by a major component manufacturer, over 50% of failures are the result of improper lubrication.  (Pins and Bushing)

  • Lubrication Related Failures: 54%
    • Inadequate Lubrication – 34.4%
    • Contamination – 19.6%
  • Installation Errors – 17.7%
  • Overload – 6.9%
  • Storage and Handling Errors – 2.8%
  • Other 18.6 %

Bearings fail in a plant for many reasons. Manual lubrication is still the dominant method of lubrication for grease bearings. 95% of all bearings are manually lubed. With plant production increasing the scheduled service time between has lengthened. Maintenance staff have generally been reduced resulting in fewer people carrying out the lubrication requirements.

Lubrication has the following functions:

  • Reduce Friction
  • Reduce Wear
  • Helps Dampen Shock or Absorb Shock
  • Reduce Temperature
  • Minimize Corrosion
  • Seal out Contaminants

Lubrication interval depends on the following:

  • Metal to metal contact area of bearing
  • Environment (Application)
  • Machine Speed
  • Operating Temperature
  • Type of Grease

Not all grease is the same. Grease is a solid or semi-solid formed when a thickening agent is dispersed in the oil base. Additives give grease their final special properties. The National Lubrication Grading Index  (NLGI) will grade the grease from 000 to 6, but this is not the whole story. Always look at the manufactures specification. Base oil viscosity can be completely different but still have the same NLGI.

Lub1 Single Block Metering Valve

Why are automatic lubrication systems better?

  • Grease evenly distributed
    • The best time to grease is when the object is in motion. This spreads the grease evenly.
  • Will not over lubricate
    • Grease is delivered by measured injection. This prevents seals from blowing out.
  • Correct amount of grease is applied
    • This will ensure the maximum life of the equipment.
  • Environmentally safe

Lubrication is a vital component to automation. MTBF can be increase if we plan on ensuring that our moving parts are well maintained.

Flo Components Ltd. is an excellent company to help you understand and maintain your systems. They have a library full of information on their website.

www.flocomponents.com/Library.htm

I encourage you to check this out and make lubrication part of your automation projects. If you have any questions, or need further information please contact me.
Thank you,
Garry



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.

Here’s a Quick Way to Wire NPN and PNP devices

Here’s a Quick Way to Wire NPN and PNP devices

I get asked often on how to wire NPN and PNP devices to the programmable logic controller. This can be confusing at first when looking at the wiring diagrams. I have managed to destroy a few sensors in the process….. so lets get started and I will share my experiences.

E2A_7069B_7l E2A_7002A_7l
NPN and PNP refer to the transistor in the output device.
NPN – Negative Positive Negative Switching. Sometimes referred to as ‘Sinking’ the load.  People have told me that when the NPN sensor blows it has a tendency to blow in an open state. (No Signal)
PNP – Positive Negative Positive Switching. Sometimes referred to as ‘Sourcing’ the load. People have told me that when the PNP sensor blows it has a tendency to blow in a closed state. (Signal On)

When the sensor blows, (malfunctions) it usually will also take out the power supply. (Fuse) It generally does not matter if you use NPN or PNP sensors provided they are all connected to the PLC using isolated commons.

You cannot mix PNP and NPN sensors on the same common point for inputs to the PLC. If you do mix the sensors, then the different common points on the PLC must be isolated from each other. This means that the commons are not connected internally to each other. Not ensuring this takes place will provide a short across the power supply and blow your sensors and supply. In general, machines tend to use all NPN or all PNP only.

Colour coding of the wires vary. Do not always rely on the colour code of the wires for connection. Refer to the wire diagrams in the documentation.

The following is a wire diagram of an open collector PNP sensor. You will notice that the load appears between the 0V (Blue)  and Switching wire (Black). When connecting to the PLC, the PLC input acts as the load. The 0V (Blue) will be attached to the common input and the Switching wire (Black) will be attached to the input number.PNP1

The following is a wire diagram of an open collector NPN sensor. You will notice that the load appears between the +V (Brown)  and Switching wire (Black). When connecting to the PLC, the PLC input acts as the load. The +V (Brown) will be attached to the common input and the Switching wire (Black) will be attached to the input number.NPN1

As you can see a direct short will be created if NPN and PNP sensors are wired into the PLC on the same common. The following shows an example of wiring of the 3 wire sensors into a PLC with isolated commons.

NPN_PNP_PLC

Watch on YouTube : Wiring NPN Sensor to PLC

Watch on YouTube : Wiring PNP Sensor to PLC

Watch on YouTube : Wiring Contact (Discrete) PLC Inputs

Wiring Interposing Relays
Watch on YouTube
: Wiring NPN and PNP Sensors into the PLC with an Interposing Relay
If you have any questions or need further information please contact me.
Thank you,
Garry



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.

How to make a Start / Stop / Jog circuit in a PLC

Looking at a stop start jog circuit in the PLC will help us in understanding the differences in hard wiring the circuit and programming.

Lets start with the basic stop stop circuit.
Here is what it looks like hard wired. (Physical switches wired to outputs devices, such as motor contactor and relays.)
Latching Relay Circuit
When the start pushbutton (NO) is pressed the power is passed through the stop pushbutton (NC) to the control relay (CR). The CR contact closes and ‘seals in’  the start pushbutton. The start pushbutton can now be released because the CR contacts allow the power to pass through to the CR.

NO – Normally Open – This refers to the state of the input  device if nothing acts upon it. 
NC – Normally Closed – This refers to the state of the input device if nothing acts upon it.

Lets take a look at the PLC program for the above wiring diagram.
start stop 001
The first thing that you will notice is that the input for Stop is NO contact and not NC. This is because the actual signal wired in the input is NC and we do not want to inverse this signal. You can see that the stop input is currently on in the program.
If we hit the start pushbutton then the circuit is complete and the output CR turns on.

start stop 002Letting go of the start pushbutton, the output remains on because the CR input seals in the start pushbutton.
start stop 003
Pressing the stop pushbutton will break the circuit and turn off CR.
start stop 004
Letting go of the stop pushbutton will return us back to the original state shown above.

Adding a jog input to the hard wiring diagram will look something like this:
start stop Jog
You can see that the diagram will work the exact same as the circuit above with the start and stop pushbuttons. The jog when pushed will break the sealing contact, and then make a bypass of the start pushbutton. This will keep the M coil on as long as the jog button is pressed. Letting go of the jog will stop the bypass of the start pushbutton which will stop M coil. When the jog returns to the original state M input will already be off so it will not keep M coil on.
The action on the jog is referred to as a Break before Make device. The jog pushbutton will break the circuit before making another connection.

Sometimes in programming a PLC it can be beneficial to think of the inputs as Make before Break. Inputs are made before the previous ones are broken. The programmable controller will scan the program from left to right, top to bottom. The outputs from the rung above are available to the rungs below. Here is a previous article on PLC scanning.
Lets take a look at PLC program with a jog that will not work.
start stop 010
Even though this looks like it would work… Remember that the contacts in the PLC are make before break. You can jog the unit and it will turn on but as soon as you release your finger off of the pushbutton the not jog input will seal the CR in. The output will not be able to turn off.
start stop 011

We must consider the delay from on to off when looking at the PLC program for this circuit.
Here is a circuit that will work:
start stop 020

Notice that we create a delay from on to off by turning on an intermediate bit in the program.

Another way to do start stop circuits in the PLC is to use the instructions Set (SET)  and Reset (RST).
The set will have all of the conditions to turn on a bit in memory and the reset will have all of the conditions to turn off a bit in memory. These instructions are used to make the program easier to view and troubleshoot.
Here is the same logic above using the set and reset instructions.
start stop 021

Notice that X10 Jog2 is in parallel with the Start. We use a trailing edge one shot in parallel with the Stop. This sets our delay so the output will turn off.

Watch on YouTube :  Learn PLC Programming – Free 4

If you have any questions or need further information please contact me.
Thank you,
Garry



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.

Adjusting Daylight Savings Time In Do-More

Adjusting for daylight saving time in Do-More PLC.

When does it start and end?
Canada Daylight Saving Time begins at 2:00 am local time on the second Sunday in March. On the first Sunday in November areas on Daylight Saving Time return to Standard Time at 2:00 am local time. When Daylight Saving Time begins turn your clocks ahead one hour. This is what happens in most parts of Canada.



There are several methods in the Do-More PLC to account for Daylight Savings Time. You can use the internet time clock, manual adjustment or use an internal bit to set daylight savings time. Since websites for internet time may not always be reliable and we do not want to wake up at 2 am in the morning to set the real time clock, we will use the internal bit method.

ST768 $SummerTime Configuration
Set this bit ON to add one hour to LocalTime to account for Daylight Savings Time.

The first line of code will check for the 3rd month (March). Then ensure that the day is between 8 and 14 so that we are viewing the second week. Next make sure the day of the week is 0 (Sunday). Finally it will check to make sure the hour is 2 (2am). The ST768 $SummerTime will then be turned on to add one hour to the real time clock in the PLC.

Daylight Savings Program ON-min

The second line of code will check for the 11th month (November). Then ensure that the day is less than 8 first week. Next make sure the day of the week is 0 (Sunday). Finally it will check to make sure the hour is 2 (2am). The ST768 $SummerTime will then be turned off to subtract one hour to the real time clock in the PLC.

Daylight Savings Program OFF-min

Adding this code to your existing logging information in the PLC can be helpful when determining the correct time.

If you have any questions or need further information, please contact me.
Regards,
Garry

P.S. In the contact section, send me a email and I will send you a link for the download of this code.



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.

Now You Can Have Robust Data Logging for Free – Part 12

Now You Can Have Robust Data Logging for Free – Part 12

HTML and Scripting Languages

 We have the following accomplished:
  • PLC program
  • Visual Basic Program
  • Data collected in a Database
  • IIS web service established
  • ASP Script Written
iis106
Lets take a closer look at the ASP Script ( AccRL.asp) that was written in part 11:
The <html> is at the start of the file and the </head> is at the end of the file. These tags all have to have a start and end.  The ‘/’ indicates the end of the tag.
The <head> is used to place the information for the web page. The refresh will load the page after 300 seconds (5 minutes). This way the information will always be the latest. Title is used to label the page. This is the information at the top of the browser. The SHORTCUT ICON is used for the icon at the top of the browser near the page address.
<html>

<head>
<meta HTTP-EQUIV=”Refresh” CONTENT=”300″>
<title>ACC Automation – Robust Logger</title>
<LINK REL=”SHORTCUT ICON” HREF=”http://192.168.1.3/ACC_Do.ico”/></head>

ActiveX Data Objects (ADO) is used to access databases from your web pages. ADOVBS.inc is a file that has all of the ADO constants defined.  Be sure to add this file in your root web application directory.
<!– #include virtual=”/adovbs.inc” –>

The <% and %> symbols indicate the start and finish of VBScript in the page. We dimension our variables for StartTime and EndTime. These will be used to determine how long our script took to execute.
<%
Dim StartTime, EndTime
StartTime = Timer

We dimension the variables that are used for the connection to the database file.
Dim OBJdbConnection
Dim rs1
Dim objCmd

We set up the connection to the database and determine what information we need to retrieve.
Set OBJdbConnection = Server.CreateObject(“ADODB.Connection”)

OBJdbConnection.Open “Provider=Microsoft.ACE.OLEDB.12.0;DATA SOURCE=C:\AccRL\data\AccRL.accdb;Persist Security Info=False;”
set rs1 = Server.CreateObject(“ADODB.recordset”)
with rs1
 .CursorType = adOpenForwardOnly
 .LockType = adLockReadOnly
 .CursorLocation = adUseServer
 .ActiveConnection = OBJdbConnection
 .Source = “SELECT * FROM Minute_Log;”
end with

Using getrows will allow us to execute the Select command and retrieve all of the information in one pass from the database.  This is the quickest method to get the information out quickly.
rs1.Open

arraytime = rs1.getrows()
rs1.close

We now write the information from the database to the page.
Response.Write arraytime(0,0) & “<br>”
Response.Write arraytime(1,0) & “<br>”
Response.Write Year(arraytime(1,0))& “/” & Right(“0” & Month(arraytime(1,0)), 2) & “/” & Right(“0” & Day(arraytime(1,0)), 2) & “<br>”
Response.Write arraytime(2,0)& “<br>”
Response.Write arraytime(3,0)& “<br>”
Response.Write arraytime(4,0)& “<br>”

The EndTime is now set and the total time it took for the process is displayed.
EndTime = Timer

Response.write “<p>Processing took “&(EndTime-StartTime)&” seconds<p>&nbsp;”
%>
</body>
</html>

Now that you have information into the database and IIS running, you can display the data in various ways.
Charts:
iis109 display
Graphs:
iis108 display Gauges:
iis107 display
This ends our robust logger design. For the complete PLC program, VB source code and web page file please send me an email and ask for the ACC Robust Logger Program. I will be happy to email you the information.
If you have any questions or need further information, please contact me.
Regards,
Garry

Now You Can Have Robust Data Logging for Free – Part 1
Now You Can Have Robust Data Logging for Free – Part 2
Now You Can Have Robust Data Logging for Free – Part 3
Now You Can Have Robust Data Logging for Free – Part 4
Now You Can Have Robust Data Logging for Free – Part 5
Now You Can Have Robust Data Logging for Free – Part 6
Now You Can Have Robust Data Logging for Free – Part 7
Now You Can Have Robust Data Logging for Free – Part 8
Now You Can Have Robust Data Logging for Free – Part 9
Now You Can Have Robust Data Logging for Free – Part 10
Now You Can Have Robust Data Logging for Free – Part 11
Now You Can Have Robust Data Logging for Free – Part 12




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.

Now You Can Have Robust Data Logging for Free – Part 11

Now You Can Have Robust Data Logging for Free – Part 11

HTML and Scripting Languages

 We have the following accomplished:
  • PLC program
  • Visual Basic Program
  • Data collected in a Database
  • IIS web service established
The machine that has the IIS web service must have the Microsoft Access Database Engine 2010 installed. This can be obtained by the following link:
You can select the 32 bit or 64 bit version that matches your computer.

Microsoft Access Database Engine 2010 Redistributable
Note:  If you have office installed on your machine already then you probably will already have this file.

ActiveX Data Objects (ADO) is used to access databases from your web pages. ADOVBS.inc is a file that has all of the ADO constants defined.  Be sure to add this file in your root web application directory. How to add this code to a web page is shown in the sample code below .
You can download ADOVBS.inc from this site in text format. (Just rename to ADOVBS.inc from ADOVBS.txt)
ADO Introduction:
http://www.w3schools.com/asp/ado_intro.asp

Lets set up ASP on IIS to display any error messages to our browser.
Call up Control Panel and then goto Administrative Tools. Call up Internet Information Services (IIS) Manger.iis100

From IIS Manager, double click on ASP under IIS. Expand Debugging Properties and change the Send Errors To Browser to True.

iis102

iis103

Lets also ensure that your browser is set to display the error messages in internet explorer (IE). Call up Internet options from the main settings.

iis104

iis105

Click the setting for ‘Show friendly HTTP error messages’. This will ensure that the error messages show up in your browser.

The last part  of our project is to display the database information to the network. We do this by using a webpage. The HTML and VBScript can be writing in any editor. (Like Notepad)

There are also a great number of online editors that you can visual see what your page will look like while developing your code.
To learn more about VBScript following the link below:
Lets take a look at the AccRL.asp file:


<html>
<head>
<meta HTTP-EQUIV=”Refresh” CONTENT=”300″>
<title>ACC Automation – Robust Logger</title>
<LINK REL=”SHORTCUT ICON” HREF=”http://192.168.1.3/ACC_Do.ico”/></head>
<!– #include virtual=”/adovbs.inc” –>
<%
Dim StartTime, EndTime
StartTime = Timer

Dim OBJdbConnection
Dim rs1
Dim objCmd

Set OBJdbConnection = Server.CreateObject(“ADODB.Connection”)
OBJdbConnection.Open “Provider=Microsoft.ACE.OLEDB.12.0;DATA SOURCE=C:\AccRL\data\AccRL.accdb;Persist Security Info=False;”
set rs1 = Server.CreateObject(“ADODB.recordset”)
with rs1
 .CursorType = adOpenForwardOnly
 .LockType = adLockReadOnly
 .CursorLocation = adUseServer
 .ActiveConnection = OBJdbConnection
 .Source = “SELECT * FROM Minute_Log;”
end with

rs1.Open
arraytime = rs1.getrows()
rs1.close

Response.Write arraytime(0,0) & “<br>”
Response.Write arraytime(1,0) & “<br>”
Response.Write Year(arraytime(1,0))& “/” & Right(“0” & Month(arraytime(1,0)), 2) & “/” & Right(“0” & Day(arraytime(1,0)), 2) & “<br>”
Response.Write arraytime(2,0)& “<br>”
Response.Write arraytime(3,0)& “<br>”
Response.Write arraytime(4,0)& “<br>”

EndTime = Timer
Response.write “<p>Processing took “&(EndTime-StartTime)&” seconds<p>&nbsp;”
%>
</body>
</html>

Place this AccRL.asp file into the root directory of our web server. Call up the page though our browser (http:\\localhost\AccRL.asp) and the following output will be seen.
iis106
In part 12 we will break down the ASP code and modify. For the complete PLC program, VB source code and web page file please send me an email and ask for the ACC Robust Logger Program. I will be happy to email you the information.
If you have any questions or need further information, please contact me.
Regards,
Garry

Now You Can Have Robust Data Logging for Free – Part 1
Now You Can Have Robust Data Logging for Free – Part 2
Now You Can Have Robust Data Logging for Free – Part 3
Now You Can Have Robust Data Logging for Free – Part 4
Now You Can Have Robust Data Logging for Free – Part 5
Now You Can Have Robust Data Logging for Free – Part 6
Now You Can Have Robust Data Logging for Free – Part 7
Now You Can Have Robust Data Logging for Free – Part 8
Now You Can Have Robust Data Logging for Free – Part 9
Now You Can Have Robust Data Logging for Free – Part 10
Now You Can Have Robust Data Logging for Free – Part 11




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.