Industrial automation systems require a large amount of safety control devices. The number of binary switching components, such as emergency-
stop buttons, door switches and pull cords placed on a typical safety system has grown over the years.
Point-to-point wiring is still the most common wiring method used in safety today. One cable from each device results in large wire bundles running through the system. Due to the sheer volume of wires, installation time is considerable and troubleshooting is complex.
Solution … ifm’s Safety at Work system
As part of an international consortium of companies, ifm efector has developed Safety at Work as one of the first fully approved industrial safety networking systems. ifm’s Safety at Work system is a simple solution to integrating safety components with one simple two-wire cable, completely eliminating wire bundles. Its plug-and-play wiring supports all topologies and can be connected to most standard plc’s and higher level networks.
Plug-and-play wiring reduces installation time and eliminates junction boxes and additional input cards. The system provides fast and flexible expansion. Any modifications to the system, such as changing or adding e-stop buttons can be made quickly and easily. Safety zones can be configured and changed through a drag-and-drop configuration software.
Safety at Work provides status indication and diagnostic information for each safety device. The system offers increased diagnostic feedback for trouble-shooting and indicates where and when a fault occurs – without the need of additional wires for feedback.
Safety at Work system overview
Safety at Work utilizes the standard AS-i protocol. This provides the backbone for the system to transmit safety related information. The basis is the transmission of dynamic code sequences (8×4 bit data sequence) which are stored in every safety module.
During installation and start-up, the safety monitor must learn these code sequences. While in operation the safety monitor constantly compares the target sequence with the current sequence of the safety module. If the safety module provides a wrong code sequence (e.g. 4×0 bit), the safety monitor switches to the safe state.
Below is an illustration of a Safety at Work system.