What does decoupling the hardware and software do?

[Rodrigo_Garcia]

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[Anonymous user · Accepted solution]

The decoupling between hardware and software is basically achieved through 2 mechanisms:

- Mapping of function blocks to different devices

- Association of symbolic links to the device's I/O (which represent a basic variable)

You start by defining your application(s) logic without caring much about the way it will be distributed/executed on the different devices.

You then select the devices you want to buy and map the execution logic (function blocks) to them. The program is calculating automatically the information that needs to be exchanged between the devices.

Finally, you may need to associate the symbolic links from your logic to the I/Os and this is again a mapping that you do once you have mapped the function blocks (that may contain some symbolic links to associate to I/Os)

In case you want to change the hardware device, you simply have to repeat this process again on the new hardware.

[Anonymous user · Accepted solution]

Yes indeed. The IEC 61499 standard enables application-centric design by separating the application model from the system model. Application programming is performed independently of the underlying control devices/resources and communications infrastructure topology which is defined by the system model.

The standard lends itself to both distributed and centralized architectures. The system model maps/distributes one or more applications by defining which parts of the applications are executed on which particular devices/resources.

A device/resource model manages the connection to the process interface (sensors/actuators via the device IO bus) and the communication interface to other devices used by the distributed application.

The combination of application, system and device/resource models enables applications to be designed independently of the underlying automation hardware, to be distributed across heterogeneous devices with zero programming effort, and for those devices to interoperate following standardized communications/data models across networks (again without additional programming).

For more information on IEC 61499, download the whitepaper "IEC 61499: The Industrial Automation Standard for Portability that Unleashes Industry 4.0".

[Anonymous user · Accepted solution]

To compliment what Adrien has said, decoupling the hardware and software has several advantages

1. I can design the application independently of the underlying hardware, and deploy at the last minute. In other words I don't have to wait to define the hardware architecture to complete the application
2. During commissioning, if last minute changes require adding more CPU's, it's a 15 minute job to redistribute the application to the new hardware configuration, with zero errors as the system auto-generates the programs and communication between controllers
3. Over the life time of the plant, it is much easier to upgrade the controllers, keeping them continuously current.
4. User's can build hardware independent  proven-in-use application libraries, that can be re-used time-and-again, irrespective of the hardware controller.
5. Calculation intensive FB's can be deployed to the appropriate hardware type, such as edge computers.