The article discusses options for solving the problem of slowing down the operating cycle of programmable logic controllers that occurs when implementing complex algorithms. For most modern programmable logic controllers, the operating cycle directly depends on the volume of the user program. The program is executed pseudo-parallel, so the complexity of the algorithm affects the slowdown of the cycle indirectly, through an increase in the code volume. The growth of the program leads to a slowdown in the controller's response to changes in the state of the inputs. In some cases, controller developers provide programmers with options that allow them to disrupt the natural order of the operating cycle, thereby reducing the response time. The advantages and disadvantages of such methods are discussed in detail in this article. As an alternative way to reduce the controller's response time, the possibility of transferring the execution of a part of the algorithm to the operator's touch panel is considered. Modern touch panels, in addition to their main task - implementing the human-machine interface, have many additional functions, including the ability to use macros. The main functionality of macros is given and the possibility of exchanging data between the controller and the panel is demonstrated. This feature is a prerequisite for delegating some of the functions of the panel controller. The limitations and risks that arise when using this approach are discussed in detail, and situations in which it is preferable to use this method are identified.

Keywords: programmable logic controller, operator touch panel, controller operation cycle, distribution of computing resources, macros

The article discusses various methods for solving the problem of lack of inputs and outputs of programmable logic controllers during construction of automated control systems. The control signals that the controller operates can be divided into two categories: the first one is responsible for direct control of the equipment system and the second one organizes the human-machine interface (HMI). The methods described in the article allow to significantly reduce the load of HMI on controller or delegate them to the operator's touch panel completely. An example of interaction between the controller and the operator panel via the MODBUS protocol is given. The pros and cons of the described methods, as well as the conditions under which they are preferable, are listed.

Keywords: programmable logic controller, programmable relay, operator touch panel, human-machine interface, control signal

The article discusses the development of a software module for controlling electric drives as part of the ModBus industrial network, which was intended for modernize the automated control system of the production line section of the "Zarya" bakery plant. Frequency converters are used to change the speed of motors in the available control system, and the operator has to manually control each converter. The rotation speed of the motors is controlled by setting the frequency value, which is inconvenient for the operator. It is impossible to simultaneously change the operating speed of all production line equipment with this control method, which leads to mismatch in equipment operation. To solve this problem, a network is being built based on the ModBus protocol, based on available equipment. The article describes the main peculiarities of the ModBus protocol, developed method, that allows the operator to specify the required system run time instead of the frequency value for each motor, and developed software module, that implements the proposed method.

Keywords: programmable logic controller, ladder diagram, ModBus protocol, controlling without feedback, frequency converter

The article deals with the imported used in the educational process controllers replacement problem. There was a need to replace imported products with domestic ones due to the withdrawal of leading import manufacturers from the Russian market, so it seems reasonable to exclude imported equipment from the educational programs of universities. The course "Digital Automation and Control Systems" is based on the study of various industrial controllers. The first place among industrial controllers in SUAI is occupied by Siemens products, which officially left the Russian market. The question of searching for similar controllers of domestic production arose, at the same time, the manufacturer should not depend on the supply of imported components. Controller PR200 by OWEN was chosen as such a manufacturer. The article compares PR200 by OWEN with LOGO! by Siemens and comes to the conclusion about the interchangeability of these controllers in the educational process. The peculiarities, advantages and disadvantages of the development environments of both manufacturers are considered in the article. It also tells about the experience of using the stand based on PR200 in the educational process, therefore, the possibility of a complete replacement of LOGO! has been proved.

Keywords: programmable logic controller, programmable relay, functional block diagrams, specialist training, substitution of imported products, development environment

The article reveals the problem, that arises as a result of generalized training of specialists according to the International Electrotechnical Commission standard 61131-3. The standard regulates the languages in which software is developed for programmable logic controllers. Training according to the standard allows a specialist to work with any controllers developed by any manufacturers, the downside of which is an insufficiently in-depth studying of the additional potentials of controllers, that are typical for the models of the particular manufacturer. Further, we consider a number of specific special functions of the FBD language using the example of programmable relays LOGO! by Siemens, which are not typical for the other devices, that work in this language, then we observe the examples of using these functions in various technological processes. Also, we get to know the abilities to transfer the parameters betweenparts of the program by using so-called link and the features of the implementationof pulse-width modulation in LOGO! controllers.And finally,we comprehend methods of working with analog signals including analog calculations and the option of non-standard using of the minimum/maximum search function as a storage element.A lot of developers ignore similar functions, because they are not covered in the training courses. Using of special functions simplifies the development of programs and provides additional capabilities for the programmer.Therefore, the necessity of a deeper studying of the capabilities of a certain controller seems to be apparent.

Keywords: programmable logic controllers, functional block diagrams, specialist training, analog signal processing, rarely used functions