Glossary · Distributed automation and IEC 61499
Resource model
Also known as: Resource (IEC 61499)
German: Ressourcenmodell
In IEC 61499, the resource model describes a resource as a functional unit within a device that has independent control of its operation, executes function block networks and provides interfaces to the device's process and communication functions, including scheduling of algorithm execution.
- IEC 61499
- Standards
In one sentence
The IEC 61499 resource model describes an independent unit inside a device that executes function block networks and schedules them.
Example
A controller device has one resource for fast machine control and one for data exchange, so the data resource can be stopped and changed without affecting control.
How it applies
- Engineering: Resources partition a device. Each resource can be configured, started and stopped independently of the others, which isolates functions and allows reconfiguration of one part without stopping the rest.
- Scheduling: The resource's scheduling function determines when algorithms run in response to events. Its behavior is implementation-specific and influences timing, which matters when comparing runtimes.
- Comparison: An IEC 61499 resource plays a role comparable to a resource in IEC 61131-3, which contains tasks and programs, but its execution is event-driven.
- Documentation: Document the resources of each device type, their intended use and scheduling characteristics, and which applications are mapped to them.
Resource vs. device
The device is the physical unit with its interfaces; the resource is a logical execution unit inside it. One device can host several resources, see Device model (IEC 61499).