Control Functions

Inconsistencies in ISO 13849 – 1:2006

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This entry is part 7 of 8 in the series Cir­cuit Archi­tec­tures Explored

I’ve writ­ten quite a bit recently on the top­ic of cir­cuit archi­tec­tures under ISO 13849 – 1, and one of my read­ers noticed an incon­sist­ency between the text of the stand­ard and Fig­ure 5, the dia­gram that shows how the cat­egor­ies can span one or more Per­form­ance Levels. If you look at Cat­egory 2 in Fig­ure 5, you will notice […]

Standards

Standards in Music

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Work­ing in a field that is stand­ards heavy, I often get ques­tions from cli­ents and stu­dents about the ori­gin of stand­ards. Recently I heard a dis­cus­sion on CBC radio talk­ing about the ori­gins of music­al nota­tion, and I real­ized that this is prob­ably one of the earli­est examples of stand­ard­iz­a­tion. Here’s the story as I under­stand it. In the early days […]

Control Functions

Interlock Architectures Pt. 6 – Comparing North American and International Systems

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industrial Control Console
This entry is part 6 of 8 in the series Cir­cuit Archi­tec­tures Explored

I’ve now writ­ten six posts, includ­ing this one, on the top­ic of cir­cuit archi­tec­tures for the safety-related parts of con­trol sys­tems. In this post, we’ll com­pare the Inter­na­tion­al and North Amer­ic­an sys­tems. This com­par­is­on is not inten­ded to draw con­clu­sions about which is “bet­ter”, but rather to com­pare and con­trast the two sys­tems so that […]