Extend RS232 RS422 or RS485 protocols over multimode fiber so different types of equipment can talk to one another in point to point or multipoint environments. Serial extenders work well in factory automation building automation and process automation where PLC's with RS232 RS422 or RS485 interfaces are used to control devices. The ability to extend the distance to their devices over fiber while also adding protection from electrical interference which can be caused by large motors which are prevalent in these environments is very beneficial.