Introduction
Although airfreight is the most efficient mode of transportation available to transport many types of goods, ocean shipping still plays an essential role in global commerce. One of the reasons for this is that cargo ships are the only feasible option for transporting large quantities of some items, such as oil, wood, minerals, and other raw materials.

Oil tankers, for example, are used to transport crude oil from the Middle East to other countries around the world. All oil tanker owners strive to build efficient fleets so that they can better manage their ships and maximize the company's profit. But how can we make the operation of oil tankers more efficient? For oil tankers, the key to efficiency is fuel monitoring and control.

New oil tankers come with newly-designed engines that save on fuel. However, a critical point to ensure safe and efficient operation is to balance the remaining fuel on the ship. Tankers have several fuel tanks located in different places on the tanker. If the remaining fuel swings, pitches, or rolls, the ship could move at a slant, resulting in a lot of fuel being wasted. To get around this problem, a system that manages and controls the 3D balancing of fuel tanks is required. Several kinds of valves and controllers control the interlinked fuel tanks. Once a sensor detects that the fuel is not balanced, the appropriate valves will be opened, and oil will be pumped from one tank to another. Since the fuel tanks are distributed around the ship and all the monitoring information must be transmitted to the control center, a redundant ring is the best solution to connect the entire system and transmit data to the control center.

Recommended Solution
Several sensors and meters are connected to the controller. A workstation in the control center takes care of gathering information of how much fuel remains, and keeps track of which fuel tanks should have fuel removed. An Ethernet network with a redundant ring collects and exchanges messages between controllers and the control center. Some controllers come with a built-in Ethernet interface, whereas others support an RS-232/485 interface. The entire system is integrated into a single communication network with industrial serial to Ethernet device servers and Ethernet switches. This type of configuration not only makes the system easier to maintain, but also makes the monitoring and control of the fuel tanks less complex.