Machinery Safety 101

Understanding Safety Functions: the start/restart function

Car engine start/stop button

After the safety-related stopping and the reset functions, the start/restart function is the next most common. Without a start/restart function, there is no way to make the machine do what it’s supposed to do. If you’re designing a machine control system, you need to understand this function.

Read More

Understanding Safety Functions: the Safety-related stop function

A stop sign - A red octagon with a white border, and white block text reading STOP.

The most used safety function on machinery is the safety-related stop function. The requirements discussed in this post are not generally applicable to process-related stop functions unless the process and safety stop functions share the same control system hardware and software. Copyright secured by Digiprove © 2021Acknowledgements: ISOSome Rights ReservedOriginal content here is published under these license terms: X License Type:Non-commercial, Attribution, Share…

Manual reset using an HMI

A Siemens HMI displaying control functions and data.

Question: Can a safety-related stop function, for example, be reset via a graphical object representing a reset button on an HMI? The short answer: No, with an exception. Read on if you’d like to know more. If you’re interested in knowing more about the manual reset function, see our previous post on the manual reset…

Understanding safety functions: Manual Reset

A reset button graphic

Following the risk assessment, risk reduction is the next step. Whenever the control system is called upon to reduce the risk, a safety function is needed. Safety functions are defined in safety requirement specifications. ISO 13849-1:2015 [1] offers descriptions of some of the more common safety functions. One of the most poorly understood is the…

Read More

ISO/DIS 13849-1 Available for Public Review

Decision tree used to determine PL based on risk parameters.

Update 2020-10-11: The next three-day ISO/TC 199/WG8 meeting runs Tuesday-Thursday this week. Our committee members will be wading into the next 1 600 comments along with expert members from around the world. We’ll update you again as the changes get closer. Update 2020-09-29: Over 1 920 (!!) comments were received by the committee from the…

Read More