Modules have different mounting options and irrespective of the mounting method chosen, the address switch is both visible and accessible for selection. Provided with built-in short circuit protection for the communications loop, to increase application flexibility, the isolators can be selected/deselected on an individual module basis. To help technicians in the maintenance and fault-finding process, multi-colour light pipes have been enlarged to increase visibility even in the most challenging space constrained application, providing diagnostic information regarding the status of each individual input/output.