AS-Interface safety at work: An introduction to networked safety

Nov. 21, 2005
AS-Interface Safety at Work (SaW) is a unique concept enabled by the modifications to NFPA 79-01 which allows emergency stopping action to be executed over a data/logic circuit under certain conditions. This White Paper describes how SaW accomplishes this.
By Michael J. Bryant, AS-Interface USA, and Dr. Helge Hornis, Pepperl+FuchsSAFETY SYSTEMS are designed to stop unsafe motion in such a way that operators are not harmed by a machine, even if the operator performs an action that would otherwise result in danger or harm. As a consequence, a safety system takes the conservative approach, always assuming that the motion must be stopped. This means that the devices involved in transmitting safety relevant information constantly transmit a “system is safe” message. If this message is not transmitted correctly (for any reason) the safety system must immediately stop the unsafe motion.AS-Interface Safety at Work (SaW) is a system that allows networking of safety devices using standard AS-Interface (AS-i) networks. With SaW users can quickly implement a safety system that satisfies the rules and regulations needed for Category 4 Safety. The simplicity of the successful AS-Interface network is retained and is a major reason for users to implement SaW systems. This White Paper outlines the features that make SaW both unique and powerful.