Machinery Safety 101

Safe Drive Control including Safe Torque Off (STO)

Graph illustrating STO Function

Ed. Note: This article was revised 25-Jul-17 to include information on safe standstill. Safe Drive Control including STO Motor drives are everywhere. From DC variable speed drives and indexing drives, through AC Variable Frequency drives, servo drives and stepper motor drives, the capabilities and the flexibility of these electronic systems has given machine designers unprecedented…

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ISO 13849-1 Analysis — Part 7: Safety-Related Software

General architecture model of software

Post updated 2019-07-24. Ed. Safety-Related Software Up to this point, I have been discussing the basic processes used for the design of safety-related parts of control systems. The underlying assumption is that these techniques apply to the design of hardware used for safety purposes. The remaining question focuses on the design and development of safety-related…

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ISO 13849-1 Analysis — Part 2: Safety Requirement Specification

This article was updated 2019-07-24. Ed. Developing the Safety Requirement Specification The Safety Requirement Specification sounds pretty heavy, but actually, it is just a big name for a way to organize the information you need to have to analyze and design the safety systems for your machinery. Note that I am assuming that you are…

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ISO 13849-1 Analysis — Part 1: Start with Risk Assessment

This post was updated 2019-07-24 I often get questions from clients about how to get started on Functional Safety using ISO 13849. This article is the first in a series that will walk you through the basics of using ISO 13849. Keep in mind that you will need to hold a copy of the 3rd…

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Why you should stop using the term ‘Deadman’

The Deadman Control Do you use the phrase ‘deadman’ or ‘deadman switch’ when talking about safety-related controls on your machinery? I often run into this when I’m working with clients who use the terms to refer to ‘enabling devices’ – you know, those two or three-position switches that are found on robot teaching pendants and…

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