RTURemote terminal units are the devices connected to the sensors, loggers, meters, or other process equipment. RTUs work under supervisory controllers or SCADA (supervisory control and data acquisition) systems. They collect data automatically from the process or device and only transfer on the command from controller. RTUs operate near the process, acquire data automatically from the system, and transfer to the controller on command.

RTU specifications

Communication type, memory size, extra features, and number of ports are the important specifications while considering a remote terminal unit. Memory is selected according to the application such as for industrial applications it requires larger memories. RTUs contain both the input and output ports. Number of I / O ports defines that with how many devices a remote terminal unit (RTU) can interact or how many devices can be attached to it. Moreover both the ports support analogue and digital inputs and outputs.

RTU Communication Types

Communication type means what type of protocol an RTU supports. RTUs support almost all sorts of protocols. These include RS232, RS422, and RS485 for serial communication. Remote terminal units also support the most common network protocol, Ethernet. RTUs support fiber optic cables that are used for long distance communication. Moreover they allow fiber optic devices supporting optical cables. Remote terminal units supporting radio, current, telephone, and video communication are also available. Web-enabled remote terminal units are also available to use Internet for communication.

RTU Physical Layout

For safety purposes Remote Terminal Units are developed to work in hazardous or risky places. I such context some devices RTUs contain entirely tight chassis that prevent them from environmental contaminants such as water or moisture. Some RTUs contain all the necessary equipment such as processor, transceivers, and encoders. Such extra equipment not only provides support to RTU functionality but also overtakes in case primary RTU stops functioning. Such remote terminal units are known as redundant RTUs. The control choice for a closed loop system includes P (proportional) Control, PD (proportional & derivative) Control, PI (proportional & integrated) Control, and PID (proportional, integrated, & derivative) Control.

RTU Features

Besides the basic specifications RTUs may contain extra features. Some RTUs contain LEDs or other blinking lights as indicators. Some have alarms indicating an error or a specific condition. Some RTUs come with auto-dialing feature. Such feature allows calling a non-dedicated number in case the data needs to be transferred. Some support differential inputs, some isolated, and some support both. Often RTUs have slots for adding FLASH or other storage devices. Some allow connection processor chips to RTUs. A few RTUs are designed to monitor only weather conditions and also for oil field exploration. Some RTUs operate indoors only, some outdoors, and some both. RTUs also differ in mounting styles such as rack mount RTUs. Almost all the RTUs contain an embedded software, real time clock, backup battery, and data logging functionalities.