What is a programmable automation controller?

The programmable automation controller can be described as an improved version of PLC a PAC is capable to do everything that the PLC can. The PAC has advanced capabilities and it is already built into its design. The PAC is capable to do certain important functions such as data acquisition, latching, loop control. The PAC also has an advantage that, because the PAC has an open architecture it can be connected to any devices which are present today. A PAC can be described as a process controller with a flexible configuration and enterprise integration strengths of a PC-based system. This device consists of certain modules and all of these modules can do specific functions such as machine control, motion control, and it can also do many industrial control applications. 

What are the characteristics of PAC?

  • It operates by using a single platform and it will be the same for the single and multiple domains and also in drives motions and process control.
  • It only employs a single development platform, which means it would use a single database for different tasks in all the disciplines.
  • Because of its good integration of software and hardware control system performance would be improved
  • It can do complex functions without any usage of additional components
  • The control systems can be easily upgraded because of the compact size of the PAC
  • The PAC only needs one software to cover all the existing automation needs

What are the advantages of a PAC over PLC and how are they different?

A PAC can do tasks like counting, latching, PID loop control, and data acquisition and delivery, but a PLC-based control system would require expensive hardware to do this. The PAC has these capabilities built-in, a PAC is known for its modular design and construction. It has an open architecture and because of this, it can connect with any other device or with business systems. A PAC has good processing and I/O scanning ability. The PAC can handle many languages like relay ladder logic, instruction list, structured test, sequential functional chart, and functional block diagram. Certain PACs can also be programmed in other programming languages such as C. By using a PAC the automation professionals have multiple tools in one platform. The PAC has more memory when compared to a PLC. Mostly the PLCs are designed to control the machinery but the PACs are used for machine control, process motion control, and other applications. The PACs are capable to improve the performance of the control system without using any extra components like a PLC. Unlike the PLC the PAC uses only one software package to address existing and future automation needs.

The PAC has another advantage, we can easily upgrade the control system. The processor hardware can be replaced without removing the existing sensor and the actuator wiring. Because of the compact size of the PAC, it won’t take a lot of space. The PACs have modern networking and communication capabilities and because of this, we can know the details of the production in real-time. Thus we can collect the data more accurately and timely and this will improve industrial production. There is a lot of financial advantage because of using the PLC the cost of the control system is lowered because the hardware is less expensive and it would only require less integration and development time. A PAC is of low cost than that of the PLC which has similar capabilities. By using a PAC instead of PLC there will be an increase in return of the assets, reduced lifecycle costs, and lower total cost of ownership. The capabilities of the PLCs are limited to specific hardware and it cannot be moved easily from PLC to PLC’s its functionality is rooted in its portable control engine. The PLCs are strong in discreet control but they can’t perform like this in other areas. Users can create and implement discrete processes, and motion control applications from the PAC’s single platform with good reliability and agility.

Mostly the PLCs are built-in proprietary technologies, the PAC widely uses the products and technologies which is commercial on the shelf. Due to this, there will be reliability and availability of the systems and the hardware and software can be easily maintained. The system price and downtime are reduced because they are available on the shelf. The flexibility and scalability of the system will be increased because of the PACs.  The PAC’s has good communication capabilities, versatile I/O options, it can handle temperature and shock, and the PAC’s also uses today’s leading communication standards.

Limitations while using the PLC

  • The control system implementation is not quick or easy due to the multiple platforms from different vendors and all of them require different programming for discrete, processes and motion logic. 
  • In order to re-engineer an existing system, it would take a lot of time, and expenses will be high too while using the PLC.
  • The current automation system would find it difficult to keep pace with the need to accommodate an ever-increasing quantity of data.
  • The amount of development in the engineering tools and platforms would be a lot to handle and this would lead to a lot of delay in specifying and implementing the automation systems and this would affect the costs too.
  • The users would hesitate to implement the latest automation control technologies because they could be outdated.
  • So if it is all set and ready to run the specified control system could perform well in one application but it will be very difficult to handle other applications and this would be a big problem. So because of this, reengineering is required and it would be a loss of time and money.

Due to all these above reasons, the PLC functionality is being improved, and that’s how a PAC is created to overcome all these limitations.

What are the benefits of using a PAC?

The PAC’s control solution would satisfy the requirements of the plants and OEM’s.

  • It can increase productivity and also operational efficiency, the PAC’s control engine would allow rapid development, implementation, and migration.
  • Because of its flexibility and openness, it would enable true control convergence and seamless integration with the operation and enterprise-level business systems to streamline the plant process.
  • It would reduce the operational costs, by using the common standard based architecture and networks, the system engineers can choose different system components for a platform that uses cost-effective rather than proprietary products and technologies, it would also provide a seamless migration path that protects the investment in both the I/O and application development.
  • By using a PAC the user would get more control and flexibility over their control system. By using the PAC system the user would have the advantage of choosing the hardware and programming language which is best suited for the application.   

What are the features of a programmable automation controller and why do we need it?

The PACs are power by a single portable unit, and it would only use a single development tool for multiple applications. The PACs would do the proper control and integration of plant floor operations with the business systems.

Features of PLC

  • It has multi-domain functionality which includes logic, motion, HMI, and process control on a single platform
  • A PAC’s is a platform for the design and integration of multi-domain automated systems
  • The PACs would allow the OEM’s and end-users to use multiple control applications on a single platform.
  • It can facilitate open, modular control architecture, and thus highly automated plant environment can be created
  • It employs the de facto standards for network interfacing and also for languages etc. So that it can allow the data exchange as a part of network multivendor systems.
  • The PAC has certain features such as surge protection, visual indicator, watchdog timers, and real clock timers

The PAC module consists of analog I/O modules, digital I/O modules, relay modules, counter modules, timer modules, and data acquisition modules. The PAC system which has analog I/O modules are mostly used to control industrial automation devices such as sensors and actuators and the PAC system which has the digital I/O modules is also used for this application. A PAC system with serial modules can coordinate the flow of data, control signals, and timing information between the data terminal equipment and the data communication equipment. A PAC has certain slots in order to add the input and output modules, Some PAC systems have Ethernet, USB, video graphics array ports. Serial PAC systems have RS232, RS485, RS422 ports. There are PAC systems which have reset button, integral power supply, and built in the webserver. There are HOT swappable PAC systems that would allow the installation and removal of modules during the operation. The PAC is capable to control, monitor, and exchange data with a wide variety of devices and systems and it is possible because the PAC uses the same standard network topologies that these devices use.


post-graduate in Electronics & communication.

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