Machinery Safety 101
12 July, 2021

Understanding Safety Functions: the Safety-related stop function

by Doug Nix
in Complementary Protective Measures, Control Functions, Emergency Stop, Functional Safety, Interlocks, Interlocks, ISO 13849
A stop sign - A red octagon with a white border, and white block text reading STOP.
This entry is part of 3 in the series Under­stand­ing Safety Functions

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… 

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19 May, 2021

Understanding safety functions: Manual Reset

by Doug Nix
in Control Functions, Functional Safety /
1 Comment
A reset button graphic
This entry is part 1 of 3 in the series Under­stand­ing Safety Functions

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… 

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2 June, 2021

Manual reset using an HMI

by Doug Nix
in Complementary Protective Measures, Control Functions, Control Reliability, Emergency Stop, Functional Safety, Inherently Safe Design, ISO 13849 /
1 Comment
A Siemens HMI displaying control functions and data.
This entry is part 2 of 3 in the series Under­stand­ing Safety Functions

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… 

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