RT-101: Real-Time Operating Systems (RTOS)

What is a Real-Time Operating System?

Known as an RTOS, the Real-Time Operating System is the heart of any Real-Time Solution. An RTOS is capable of executing programs with extremely accurate timing creating a very deterministic system. This key benefit is often highly desired for many scientific, engineering, and industrial automation projects.

Real Time Operating Systems can be great replacements for PLCs where harsh conditions and extended run periods require robust execution. An RTOS also provides an excellent solution for safety monitoring applications or any critical process where interruptions in execution can have extreme consequences. Real Time control can even be incorporated into existing systems (i.e. vision or motion applications) to add reliability and performance.

Common Real-Time platforms such as VxWorks, Phar Lap ETS, QNX and many others can provide the following benefits:

Determinism

In many measurement and control applications, the use of a general purpose operating system (i.e. Windows or MAC OSx) is not acceptable. General purpose operating systems are designed to efficiently run numerous applications at one time. While highly beneficial to the average consumer, these characteristics can mean failures within mission critical programs. Imagine a laboratory safety program running on a Windows PC. At any given moment the OS may decide to pull resources away from the safety program to update user interface graphics, run a virus scan, perform any of numerous background tasks and more. This lack of resources and/or delay could cause the safety program to fail putting lab technicians at risk.

In contrast, all RTOS platforms are designed to execute a single program. This ensures that resource juggling does not occur and the system maintains highly deterministic execution. Specifically, an RTOS allows the programmer to do the following:

• Execute actions and events with a guaranteed processing time
• Identify any missed timing goals
• Accomplish extremely precise loop timing (often within microseconds)
• Separate different sections of the program and assign priorities to each

Dependability

In addition to deterministic execution, an RTOS can provide robust and reliable long term operation. A real-time computing system can be designed to run for weeks, months or even years without interruption. Additionally, it has the “turn-it-on-and-it-works” operation expected of dedicated industrial controllers. This provides piece of mind to engineers designing systems that need to operate 24 hours a day 7 days a week, but can also be extremely beneficial when system down-time can mean significant financial costs.

RT-201: PLCs vs. Real-Time Systems

RT-301: Capabilities of Distributed LabVIEW Real-Time

Learn more about DMC's LabVIEW programming for real-time and FPGA services.