Security Gateways: The following information comes from the IoT Solutions World Congress 2016 held in Barcelona. One of the speakers at the conference was Andrew Ginter, VP of Industrial Security at Waterfall Security. The company offers solutions for one-way Security Gateways.
Can they replace firewalls in industrial network environments? They provide complete protection to control business systems and networks from attacks originating from external networks.
Unidirectional gates are a technology that is divided into two parts: there is a TX device that contains a laser, and an RX device that contains an optical receiver. 
Security Gateways pairs can easily transmit information from a business network, but prevent the propagation of any virus, DoS attacks, human error, or any information from the protected network.
Waterfall Security's software collects real-time data from every task of the servers located within the protected network. The software transmits the data to the external network, through replica servers that contain the data.
Waterfall Security provides capabilities for dozens of replicated industrial applications, including process history, database processes, server control systems, OPC servers, and low-level devices.
Replication solutions are also available for file servers, mail servers, print servers, SIEM servers, and other components necessary for integrating modern networks into enterprise networks.
The server-replication process is not visible to external users, and has no effect on the original servers' operations. External users have access to use the replicated servers in the same way they would use the original servers, without changing anything in the work processes.
