Using function blocks to implement flexible and cost-effective ......prefer the function block...

Using function blocks to implement flexible and cost-effective automation projects

Flexible controls for small to medium-sized machinesWhite paper

Ulrich KanngießerFirst edition

2 EATON – Flexible controls for small to medium-sized machines

White Paper WP050002ENOctober 2019 edition

Using function blocks to implement flexibleand cost-effective automation projects

Content

1 The control relay programming language 04

2 Graphical programming functions 05

3 STRUCTURED TEXT (ST) in detail 05

4 EDP (EASY DEVICE PROGRAMMING) – programming on the device 06

5 Modular hardware and software 07

6 Highly dynamic drives – interrupt function blocks 08

7 easySoft7 – a universal software tool for project development 08

8 Display design tools – TEXT DISPLAY 09

9 Simulation 10

10 Conclusion 10

Author

Ulrich Kanngießer

Expert author and seminar leader

3EATON – Flexible controls for small to medium-sized machines


Smart automation – control relaysBy now, control relays have become firmly established in many areas of automation, and thanks to their easy handling, wide range of options and low training threshold, they have led to significant cost savings. In the past, however, the number of available inputs and outputs of the control system often proved insufficient, or the function blocks needed for more specialized applications were missing. If this was the case, or if the experts in charge simply didn’t like working with the ladder diagram or the function block diagram, automation concepts created with these methods frequently had to be converted to another control system.

It doesn’t make sense to dispense with control relays altogether, since a typical PLC cannot simultaneously be used for control, visualization, operation and configuration while also serving (in the EDP programming language) as its own programming device.

The latest generation of small controllers offers greater flexibilitySmall controllers benefit from recent innovations in networking technology, integrated visualization options and greater expandability of the input/output level. The manufacturers of small controllers offer technology modules for specialized applications, for example in order to support measuring functions, control tasks, drive systems and many others.

Manufacturers typically offer the following function blocks:

• data and register function blocks

• open-loop and closed-loop function blocks

• pulse output and pulse-width modulation

• scaling and conversion functions

Nevertheless, these manufacturer-designed function blocks are not sufficient to cover all possible applications. That's why it's all the more important that users can create their own user-defined function blocks (UFs), based on the logic of a higher level programming language. These UFs are not only able to handle user-specific technologies, but also

provide users with a technical advantage. Programming with structured text (ST) offers the flexibility required for these diverse tasks, and they can now be implemented using the new easyE4 small controller.

The costs of small controllersIn modern automation projects, the costs of software development, commissioning, system maintenance and the application software by far exceed those of the control system. Companies have to invest a lot of time and effort if the entire commissioning is to be carried out by IT and system specialists. In addition, the commissioning time can also be reduced by choosing a procedure based on tested software modules. Therefore, the advantages of comprehensive and powerful simulations cannot be overstated.

Summary: Modern control relays are no longer limited to smaller applications. In fact, they provide an economical alternative for tackling increasingly complex tasks and offer end users considerable added value at beneficial cost.

In the following, this will be illustrated using the example of the new easyE4 control relay.



1 The control relay programming language

The choice of programming language should always be based on the task at hand, as well as on the expertise of the personnel that will commission and service the future system. Graphical programming methods (such as the ladder diagram or the function block diagram) are unambiguous, generally understandable and easy to learn. However, these programming languages are not very popular with system specialists when it comes to more complex tasks such as extensive calculations, alternative decisions, loop constructs and data management.

1.1 Modular software

Apart from the specific capabilities of the programming languages and the possibility of combining them, cost-effective automation concepts also rely on the option to create software modules. When users define their own function blocks, they need to decide whether they simply want to combine individual language elements (such as contacts or coil assignments) and modules, of if they want to use a text-based programming language to create complex function blocks that can be managed in a library. Importing and exporting such tested and proven user-defined function blocks reduces the time required for implementation as well as the overall costs, as these modules can then later be reused for future projects.

Users may find it useful to create their own software modules for various reasons, and these will briefly be explained below.

Reusable modules significantly reduce the development time for circuits featuring identical interlocks and monitoring systems, such as those typically used in drive or pump controls. Similar requirements also exist, for example, in the areas of building services engineering, HVAC and lighting systems and door controls. Within certain limits, it is possible to create function blocks (UFs) in the ladder diagram or the function block diagram that can then be used again and again.

This is based on the principles of machine building and system integration, where modular thinking and standardization techniques (i.e. conveyor belts, pallet warehouses, transfer stations, automatic turners in cheese making, etc.) are used to reduce costs, shorten commissioning times and avoid errors. Based on this modular approach, software modules are now being developed that correspond to and represent the mechanical components.

An additional reason why users may want to create their own UFs is that the existing function blocks offered by the manufacturer are simply insufficient for the required functions or the complexity of the task at hand. In such cases, a powerful programming language like ST is required in order to be able to implement the application using a small controller.

Another reason why users may want to create their own UFs is to make efficient use of the controller's system resources (e.g. the cycle times or memory). Manufacturer function blocks provide a wide range of functions and are universally applicable, but also require more system resources. User-defined function blocks, on the other hand, are designed for specific functions and are optimized for the application in question.

Why is a modular set-up especially interesting when it comes to compact controllers? The functioning of these small automation systems is not based on programming, but on calling up, connecting and configuring ready-made function blocks (counters, timers, controllers, etc.). If ready-made function blocks are used consistently, solutions of this type can be deployed even for very large tasks while remaining comprehensible and traceable.

1.2 Ladder diagram

The ladder diagram (LD) is a standardized graphical programming language for programmable logic controllers (PLCs), based on the circuit diagrams of general electrical engineering. LD enables the connection of actuators (contactors, valves, etc.) and their interlocks with each other. It forms the basis of electrotechnical training and corresponds to traditional circuit diagrams with electromechanical switching elements and devices. In today's contact diagrams, this method of representation is combined with the function block diagram. However, it is important to distinguish between today’s free ladder diagram and the previous version of the ladder diagram, which was characterized by a limited number of serial contacts.

1.3 The function block diagram

The function block diagram (FBD) is another graphical programming option. It uses symbols from Boolean algebra and displays them in block diagrams. This makes it possible to display the logical structure of PLC programs in a clear and transparent manner. The function block diagram is especially suitable if a large number of function blocks need to be configured and connected. However, some companies also prefer the function block diagram simply for historical reasons.

1.4 Structured text

The possibility of developing powerful, ready-to-use user-defined function blocks in structured text (ST) represents a significant advance in automation. By defining, creating and integrating their own function blocks, users can implement special technologies at the same level as that of a manufacturer function block. This enables users to save costs and to store their know-how in a future-proof and reusable way. ST is based on the work of Isaac Nassi and Ben Shneiderman, which made jumps and rebounds in software design obsolete.

1.5 Combining programming languages

On its own, none of the programming languages is ideal for solving all the problems associated with implementing an automation project and meeting the expectations of everyone involved. A very abstract programming language, such as structured text, is helpful for specialists, but creates dependency on experts. For this reason, it is helpful if the programming languages can be combined with each other as required. Experienced engineers will appreciate the option to write complex rules or data processing code in ST, while the work of electricians is made easier if they can use the familiar ladder diagram to check and modify the interlocks and parameters. Function blocks created in ST can be integrated in the LD, the FBD or again in ST.

1.6 Comparing the programming languages / methods

While the ladder diagram and the function block diagram are very similar and also use the same terminology (coils, contacts, etc.), ST is based on the text-based programming languages that are now commonly used in technical training and engineering. While the LD and the FBD can be compared and exchanged at any time, ST differs considerably in terms of the tasks to be performed, the options for creating and editing programs and the requirements placed on the programmer or commissioning engineer.



Summary: It is only by combining the various programming languages that the full potential of small controllers can be harnessed. The resulting diversity contributes to shorter implementation times, a lower degree of dependence on experts, greater user acceptance and powerful solutions at lower costs. This supports the consistent application of the modular principle in machine building.

2 Graphical programming functions

Graphical programming methods are helpful if the commissioning of a system primarily involves testing the interlocks and configuring the manufacturer and/or user-defined function blocks. Traditionally, there are a lot of people in companies who are familiar with the LD and the FBD and their application, and this knowledge is not usually limited to trained electricians.

2.1 Ladder diagram – LD

The ladder diagram is one of the oldest and most traditional programs in automation technology and is therefore both widely known and accepted. Even electricians who have not worked with automation systems before know the ladder diagram from their daily work – and thanks to the latest generation of small controllers, it now offers even more flexible and powerful programming options.

Like the function block diagram, the ladder diagram is structured around networks, which have been used in automation for many years. As soon as a new circuit-diagram network is created, a system-generated number will appear in the header along with the user-definable jump label. In addition, a free comment can also be assigned. This is already the first element of a modular system.

The jump label (or simply label) is necessary if jumps are to be used and, alongside the network number, it also serves to identify the network in question. Jumps are sometimes inevitable in the ladder diagram, and it is only in ST that they can be completely avoided.

Fig. 1: A network in the ladder diagram

2.2 Function block diagram – FBD

The function block diagram uses standard logic modules to represent the logical elements. These modules are connected to the electronic components in the logic diagram. The number of inputs and outputs of the logic modules can be adjusted by means of the [+] or [-] keys. This option creates a high degree of programming flexibility and makes the program or circuit diagram more user-friendly and comprehensible.

Fig. 2: A network in FBD: The AND function can be extended with the "+" key.

2.3 Configuring the function blocks

In the LD as well as in the FBD (and also in ST), the configuration of the manufacturer and user-defined function blocks uniformly takes place below the circuit diagram, as soon as the corresponding function block has been selected.

However, as part of this configuration, users do not only assign the necessary variables or values, but also select and set the functionality. This uniform set-up makes it easy to handle the system and to quickly learn how to use it.

Fig. 3: The process of adjusting and configuring the function blocks (timing relays in this example) is the same across the different programming methods.

2.4 The limits of graphical programming methods – jumps

More complex structures, including looping, are also possible in the LD or the FBD, but only in conjunction with jump statements. However, these are no longer being used in today's software technology. Instead, ready-made and generally accepted constructs such as alternative decisions (IF ... THEN ... ;) or standardized loop constructs or case decisions such as "WHILE...", "CASE..." etc. are used.

3 Structured text (ST) in detail

The use of ST in the easyE4 devices is aimed at achieving a high level of performance combined with easy handling and short training periods, as is typical for a control relay.

The capabilities of the integrated manufacturer function blocks are a hallmark of the quality of small controllers, which also go by many different names, depending on the manufacturer. One option for expanding the functionality of an existing device is to turn to the manufacturer for additional, supplementary technology modules. However, it is much more appealing for users to create their own protected function blocks using a text-based language such as structured text. The easyE4 from Eaton offers this option, which also corresponds to the existing command set, memory model (markers and net markers) and operands of the controller.



3.1 Indirect addressing of operands

The language range has been optimized for the requirements of a small controller, but more complex data processing tasks can be realized by means of pointer access (pointer or index) to the easyE4 operands.

Example of direct addressing in ‘easy’ ST:

The value of MW100 is transmitted to MW51: MW51 := MW100 ;

Example of indirect addressing in ‘easy’ ST:

The value of the MW that is determined by MW20 (pointer) is transmitted to MW51: MW51 := MW[MW20] ;

This means that the necessary loop constructs, alternative and case decisions required for using the extensive possibilities of indirect addressing are available.

3.2 Program controls – case distinctions and looping

Since the 1970s, jumps and rebounds have been considered outdated, and structures have been developed that make jumps fully obsolete. These structures are known as Nassi-Shneiderman diagrams (or NS diagrams) and have resulted in the software constructs that are in use today.

Description: Application of a WHILE loopA marker WORD group (MW100 to MW109) is to be searched for the presence of a specific value. If the value is found, the address of the MW is to be stored in MW97 and a message bit M10 is to be set.

While MW 99 < 110 and not M10

Test value reached?

YesNo

Transfer MW number

set message bit

Increment MW99

Fig. 4: Nassi-Shneiderman-Diagram for "search value"

Fig. 5: The associated program (WHILE – loop) in the easyE4 version of structured text.

These advanced concepts were also adopted in the easyE4 version of ST. This includes case decisions such as the IF...THEN... and CASE...OF statements, as well as loop statements such as the WHILE...DO, FOR...NEXT, and REPEAT...UNTIL constructs. In easySoft7, these language constructs are represented graphically as text modules.

Fig. 6: Working in ST is supported by ready-made text modules.

Summary: With today’s control relays, the manual drawing of circuit diagrams is a thing of the past. ST provides programmers and commissioning engineers with a powerful tool that has been optimized for more complex tasks that were previously not possible.

4 EDP (easy device programming) – programming on the device

From the beginning, small controllers/control relays were always available with a display and programming keys – in other words, they offered a fully programmable control unit, programming unit and operating and display unit in a single device.

The easy device programming language (EDP) makes it possible to carry out the entire programming process on a computer. In addition, EDP can also be used to simulate the application software and to visualize it on a PC. However, the technicians commissioning the controller will generally find it useful to be able to check the current status of logic links, to adjust the parameters and to carry out reprogramming without a PC or other aids, simply via a browser, tablet or smartphone.

That being said, the EDP programming method does not permit subroutines and is not compatible with the programming languages described above. However, a device that has been programmed in EDP can be integrated into a state-of-the art ‘easy’ network, with all the communication options it offers (data exchange).

Fig. 7: Using a PC for programming offers greater flexibility than entering data on the controller.

4.1 Online diagnostics – EDP

The EDP programming method offers the unique advantage that the circuit diagram can be displayed on the device itself. Consequently, status tracking is also possible via a web browser, provided that an Ethernet connection is available.

MW97 : = 0; // Marker WORD with ConcordMW97 : = 88; // Value to search forMW99 : = 100; // Set pointer to startM10 : = FALSE; // Bit - Value is correct - RESET// Search value using the WHILE loopWHILE MW99 < 110 AND NOT M10 DO IF MW98 = MW [MW99] THEN // Test value reached MW97 := MW99; // Value reaches MW-No at MW97 M10 : = TRUE; // Set bit value rached END_IF ; MW99 ;= MW99 + 1 ; // increament pointer END_WHILE;



Fig. 8: Status tracking in EDP via web browser on a PC, tablet or smartphone.

4.1.1 Programming on the device / web programming

Via a web browser, the same actions can be performed as on the device itself, including programming or reprogramming. Normally, controllers are not programmed directly on the device. Nevertheless, this option is available and may be helpful in certain challenging situations.

Fig. 9: Reprogramming via a web browser.

Summary: The option to program the control relay directly via the display enables quick interventions and provides an overview of the controller status at all times. However, the option of programming the device via a PC offers greater flexibility. Depending on the application at hand, either option or mode of operation can be selected.

5 Modular hardware and software

Modular designs have made a significant contribution to reducing costs and shortening the development and commissioning times in machine building and systems engineering. With standardized, uniform machine components, higher production quantities become possible. These components also simplify the planning and construction of machines. At the same time, production facilities can also be designed with a high degree of flexibility for future expansions or conversions. As a result, modular systems enhance investment security.

The easyE4 meets all these requirements, thanks to the easySoft7 development software, the device hardware and the networking concept (local easyConnect as well as remote easyNET or Modbus connections).

5.1.1 Modular hardware design

The hardware design allows for modular scaling, i.e. whether the controller is set up in a central or remote manner depends only to some extent on the number of inputs and outputs. When it comes to hardware design, the decisive factors are the end customer's installation needs, the mounting and wiring requirements, the anticipated functional tests and the available commissioning time.

5.1.2 Modular software design

Machine and system assemblies can be represented as user-defined function blocks, which enables the creation of software in line with the mechanical solution approach. In other words, just as a production facility is assembled from prefabricated systems, the software is also assembled from proven modules (user-defined function blocks / UFs).

Main program establishing Interrupt-Routine

same main program

UF-user function arbitrary

LDLD

UF01 ST

UF02 LD

UF03 FBD

UF04 ST

UF05 FBD

FBDFBD

STST

EDP

Fig. 10: Modular software designs and the applicable programming methods.

5.1.3 Designing modular networks

The easyE4 connects the individual devices (and thus the mechanical modules) via easyNet-based networks and, if required, also via MODBUS TCP IP, using the same Ethernet cable. The easyE4 offers these networking options without any additional costs.

The network set-up also has to follow the 'easy' logic to ensure that the technology does not create any dependencies on experts. For this reason, users can rely on proven manufacturer function blocks (PT, GT or PUT GET) and also have numerous variables at their disposal that are automatically exchanged via the Ethernet-based easyNet network. This means that there is hardly any additional programming effort, irrespective of whether a central or remote approach is used.



In addition, individual easyNet networks can communicate with each other as a group (NET group), and this modular approach can also be used to design large-scale production and other systems.

Summary: The hardware design, the application software and the available networks all support the implementation of modular systems.

6 Highly dynamic drives – interrupt function blocks

As a rule, machines and systems are evaluated based on their productivity, performance speed and daily output variations (set-up and changeover times).

Counters, like those used in distance measurements or conveyor technology, require rapid reactions in real time, and the same is true if inputs need to be switched to enable the precise positioning of packages, workpieces or products. The processes used for speed measurements, part tracking and positioning as well as weighing similarly require short response times or even interrupt capabilities. Precisely for this reason, the new easyE4 control relay comes with integrated interrupt capability.

The interrupt routines enable the control relay to react to external signals, error messages or similar signals without any time delay and to execute the corresponding responses, much like a PLC.

Counter-controlled, edge-controlled and time-controlled interrupt routines are available, similar to those of a more complex PLC.

IC - Counter-controlled interrupt

ID - Edge-controlled interrupt

IT - Time-controlled interrupt

Interrupt function blocks

Fig. 11: Examples of using integrated interrupts to start programmable routines: an interrupt routine triggered by a counter, an interrupt triggered by a signal edge (e.g. the speed of a conveyor belt) and a time-triggered interrupt.

6.1 Programming the interrupt routines

Interrupt processing also follows the 'easy' concept based on modular function blocks and relies on familiar programming methods. The necessary interrupt responses can be defined by means of the corresponding routines. Programming is done in the ladder diagram, the function block diagram or structured text.

However, the scope of the individual languages has been adapted to the requirements of interrupt routines. Within each interrupt routine, both the inputs and outputs of the function block and the physical inputs and outputs of the base unit are available. It therefore makes sense to reserve the I/O level of the base unit for faster processes.

Summary: Modern control relays can be used to successfully implement time-critical, complex and highly precise control processes in a cost-effective way.

7 easySoft7 – a universal software tool for project development

easySoft7 is the universal project development tool for the easyE4 devices, as well as for the associated network connections and the necessary settings. Besides the capabilities of the available programming methods (LD, FBD, ST, EDP), the decisive factors for the cost and performance of an automation solution are the tools used to create the project and develop the application software.

The requirements for modern automation development tools therefore go far beyond programming and range from the selection of the devices to the simulation of user-created programs. For this reason, it makes sense to use the term ‘integrated development environment’ (IDE).

7.1 The functions of easySoft7

The functions of modern development platforms include:• defining project designs

• setting up device configurations• controlling access via web• setting up email transfers

• creating programs for all project devices using different programming methods (LD, FBD, ST)

• transferring programs / communication• formatting SD cards and administering data • transferring logged data to a computer• scanning, detecting and identifying IP participants in the

network• simulation

• verification of logic functions• testing and documenting the visualizations• verifying the mathematical calculations• checking the indirect operand addressing for robustness• carrying out tests that would hardly be possible once a

system is running (e.g. adjusting the breakpoints)

7.2 Advanced options for creating programs in ST

Experienced programmers tend to prefer ST because it allows them to create programs using a simple text editor. Word processors (such as Microsoft Word) usually come with extensive copy, search and replace functions, as well as text modules and macro options. The program code and the corresponding comments can then be transferred (copied) to the development platform of the automation device and checked for syntax errors using the standard word processor (programming). The software can then be tested in simulation, including the setting of breakpoints. A further advantage is the option, within limits, to transfer program code from other ST-programmable automation systems.



7.3 Tools for creating the application software

In addition to easySoft7, which is used to develop the application software, the computer platform and the required operating system also need to be taken into account. easySoft7 makes only minor demands on a PC or laptop in terms of processor performance and memory expansion. Although the use of Windows 7 is generally declining, this operating system shouldn’t pose any problems, and it also allows for easySoft7 to be quickly installed on older computers.

7.4 Project development via web browser

Another possible commissioning tool is the internet in combination with a web browser. In all programming methods (LD, FBD, ST, EDP), the states of operands and of the manufacturer and user-defined function blocks can be read and set by means of a web browser running on Windows, Apple, Android, etc. The web browser can also display visualizations in color, and the activated P keys can be used accordingly. If the programming was realized in EDP, the device can even be reprogrammed via the internet browser.

Summary: The hardware needs for developing the user software are not very high; the powerful easySoft7 development platform meets all modern requirements, the demands on the PC are low, and the internet browser options are groundbreaking.

8 Display design tools – text display

Modern automation systems are not only used for control tasks, but also for implementing simple display and operating levels. A special feature of control relays or smart automation systems is that they are equipped with a display and keys that can be used to implement a simple HMI.

The necessary tools are integrated in easySoft7. The configuration form, which opens when a function block is called up, activates the tools for creating a simple user interface in color.

8.1 Designing the visualization

The integrated visualization can be set up with various objects and in several languages. The underlying philosophy is the same: a lean tool with powerful capabilities and a low training threshold. Nevertheless, structured language management is possible (the visualizations can be designed in several languages) and variable-dependent message texts are also available. The multi-color display is only one of many available features.

8.1.1 Elements and objects

The display screens are created from different objects or elements with several options (display only / display and operability), and they can also be displayed in different colors.

Fig. 12: The word ‘alarm’, the bar graph and a color change from green to red are used to indicate the presence of an alarm message.

Display elements:• Value display• Bar graph• Bit display• Running text• Rolling text• Message text• Date and time display• Timing relay value display

Input elements:• Value input• Latching pushbutton• Message text selection• Date and time input• Timing relay value input

D

V

M

A

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m

i

a

a

c

v

x

x

t

E

.

B a c k : P 1

r r I n K r :

: 9

9

9 9

9

9 9 9

c m / S

e f

F

o

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r

r

m

m / h

Fig. 13: Creating a visualization – the display is an important feature of small controllers.



8.1.2 Designing human-machine interfaces

The visualization options outlined above are of particular interest in system integration and machine building applications, as they allow users to create their own commissioning menus, including process controls with position windows, performance monitoring and many other functions. Since the integrated display of the small controller is not always sufficient for operating a machine or system, additional external displays are often required, which is why it is possible to transfer the display information to a touch screen via the integrated Ethernet interface. No additional visualization software is required on these devices if the easyE4’s IDE representation is deemed sufficient. This makes it possible to implement cost-effective human-machine interfaces. And given the option to install additional visualization software on the touch displays or to use different display sizes, ease of use is guaranteed.

Fig. 14: External easyE4 display running the powerful GALILEO visualization software.

Summary: Control relays can be used to implement small, tailor-made visualizations that come close to the possibilities offered by a fully-fledged visualization system, and in combination with larger external touch panels, they can also be used to implement a complete HMI.

9 Simulation

Simulations are an important tool for ensuring that the commissioning process starts with software that is as error-free as possible. Certain errors, which may lead to the sudden termination of the automation program’s cyclic processing, can thus be eliminated before the actual commissioning takes place. This significantly reduces the commissioning time of the system and also lowers the costs.

For this reason, the easySoft7 development platform comes with an integrated simulation option. This makes it possible to carry out numerous checks before commissioning, which will be explained in detail below.

9.1 Simulating the functions

Simulating the circuit functions is the ideal way to test and verify automation ideas and solution strategies before implementing the actual controls.

9.2 Setting breakpoints

It is very difficult to isolate mathematical calculation errors during the cyclic processing of a typical PLC. With the simulation programs for small controllers that are available today, it is possible to carry out mathematical calculations instruction by instruction and to test various parameters. In this way, complex mathematical calculations can be thoroughly checked before commissioning.Even more serious are pointer errors in indirect addressing. Operating errors, defective input devices or interruptions in the power supply can lead to erroneous pointer access to operands in the software, which may result in damage. It is therefore necessary to thoroughly investigate the likely causes of pointer errors as well as the possibility of safe error responses (the robustness of the user software).

9.3 Settings and monitoring made easy with the oscilloscope function

With the control relay's oscilloscope function, analog signals can be tracked and viewed in relation to other variables. This makes it very easy to test analog signals before they are put into operation, and to eliminate or detect sources of error.

In this example, the oscilloscope has recorded a ramp that was generated by a constant cycle time (ST function block).

Fig. 15: The oscilloscope function makes it possible to adjust and monitor the settings of analog values.

9.4 Simulating the visualization (text relay)

The entire visualization can be tested in simulation mode. In addition, this option can also be used to train commissioning and maintenance staff or to create project-specific manuals.

Drive Form

MaxErrInkr:

Act. Form/h

Back: P1

4

Vmax: 55cm/s

2978

Fig. 16: Example of the commissioning and maintenance screen of a control relay (simulation).

Summary: The powerful simulation function saves valuable time during programming, commissioning and delivery of the project.



10 Conclusion

In recent years, many experts have questioned the usefulness of control relays because circuit-diagram-based graphical programming is widely perceived as too restrictive and inconvenient. In addition, the devices were often simply not flexible or expandable enough for more complex applications. However, as this white paper has shown, the scope of application for small controllers has increased considerably thanks to scalable programming languages and the option of modular expansion – and for many applications, even those of medium complexity, they now offer a cost-effective and user-friendly alternative to a classic PLC. • And the fact that the digital and analog inputs and outputs of

the easyE4 can be easily expanded means that later system changes usually won’t be necessary.

• The modular software supports the implementation of equally modular machine and system designs. In addition, it can also be reused in similar applications, which significantly reduces commissioning times.

• By using their own tailor-made and protected function blocks, companies can build up a specialized library of function blocks that can then be reused in any small controller and even – in slightly modified form – by a PLC.

• Numerous other functions such as interrupts, highly-precise off-grid time synchronization, several language versions within one system and the integrated visualization option turn modern control relays into a new class of smart automation device.

Further reading

Ulrich Kanngießer: Programmierung mit Strukturiertem Text, Berlin 2018, VDE Verlag

Ulrich Kanngießer: Steuerung und Regelung mit easyE4, Berlin2019, VDE Verlag

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