Understanding Remote Digital Terminals for Industrial Control

Remote digital terminals are a game-changer for industrial control, allowing operators to monitor and control equipment from a distance.

They can be connected to a computer or other device via a network, making it possible to access and control equipment in real-time.

This can be especially useful for equipment that's located in hard-to-reach areas or in harsh environments.

Remote digital terminals can also be used to collect data from equipment, which can be used to optimize performance and prevent downtime.

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An RTU can be structured in different ways, including centralized, decentralized, or a mix of both. The choice of structure depends on the specific needs of the system.

In a centralized structure, the RTU is based on a common parallel system bus, such as VME BUS or PCI BUS. This includes system-CPU modules with PowerPC or ARM processors, as well as various passive and intelligent peripheral modules.

The centralized structure typically consists of a main CPU module, a different number of single board computers - bay controllers, and a different number and type of extension peripheral modules, as well as communication controllers. This allows all device signals to be delivered to a given RTU.

For more insights, see: Digital Access Carrier System

Here are some key components of a centralized RTU structure:

Alternatively, a decentralized RTU structure fetches device signals locally, directly on the technological devices, and delivers them to the main CPU serially or via local LANs. This approach is often used in systems where device signals need to be processed quickly and efficiently.

In some cases, an RTU may be structured as a single complex circuit card with various sections needed to perform a custom-fitted function. In other cases, it may consist of multiple circuit cards, including a CPU or processing with communications interface(s), and one or more of the following: analog input, digital input, digital output, or analog output cards.

This flexibility in RTU structure allows for a wide range of applications and system configurations.

A fresh viewpoint: Network Interface Device

An RTU, or Remote Terminal Unit, is a digital device that collects data from the real world and transmits it without loss to a specific object, like a controller or software.

RTUs support various function groups, including communication functions, acquisition and primary data processing functions, and control functions.

They acquire and process information inside the object, supervise and control technological processes, and manage data coming from neighboring objects.

RTUs also select, prepare, and deliver process data to different Control Centers, archive and log object information, and provide local operators with complete technological, operational, and diagnostic information.

Here are some key RTU functions:

These functions enable RTUs to collect and transmit data efficiently, making them a crucial part of many industrial and commercial systems.

A Remote digital terminal, also known as a Remote Telemetry Unit (RTU), plays a crucial role in data communication between remote locations and control rooms.

RTUs support two main communication levels: process and object. The process level involves data transfer between the RTU and Intelligent Electronic Devices (IEDs), such as protective relays, measuring devices, and Bay controllers.

RTUs can work with various communication protocols, including IEC 60870-5-101, IEC 60870-5-104, IEC 60870-5-103, IEC 60870-5-102, and Modbus.

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In addition to these protocols, RTUs can also support standard protocols like Modbus, IEC 60870-5-101/103/104, DNP3, IEC 60870-6-ICCP, and IEC 61850.

RTUs can work in parallel as Server/Slave to more than one subscriber – Clients/Masters. They can select, extract, or deliver required data to each subscriber.

In case of information loss caused by connection injury, the RTU preserves all events occurring in the meantime and resends them on connection recovery.

Here are some of the communication protocols supported by RTUs:

RTUs can also support wireless and wide area network applications, working well on High and low speed networks. They may be interfaced to multiple master stations and IEDs with different communication media, such as serial (RS232, RS485, RS422) or Ethernet.

The configuration of a remote digital terminal is designed to be user-friendly. The ruggedized tablet with touch screen operation makes it easy to navigate and interact with the system.

The interface of this terminal is also noteworthy, boasting simple and intuitive controls that make it accessible to users of all skill levels. This streamlined design ensures that users can quickly get up to speed and start using the system without any hassle.

A common database is also a key feature of this terminal, allowing for seamless integration and sharing of information across different users and locations.

Let's dive into the configuration options for our device. A ruggedized tablet is a great starting point, allowing it to withstand rough handling and harsh environments.

The ruggedized tablet comes equipped with touch screen operation, making it easy to navigate and interact with the device.

This configuration is perfect for professionals who work in the field, such as construction workers or first responders, who need a reliable and durable device to get the job done.

The interface of a product is what makes it easy to use and understand. Simple, intuitive controls are a hallmark of good interface design.

The OSRVTTM, a product used by the U.S. Army, has a common database that allows for streamlined access to information. This database is a key component of the product's interface.

A simplified HMI, or Human Machine Interface, is also a feature of the OSRVTTM. This means that users can easily interact with the product without needing extensive training.

All products are trademarks or registered trademarks of their respective owners, but the OSRVTTM's interface is designed to be user-friendly and efficient.

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Modern RTUs are capable of executing simple programs autonomously, simplifying deployment and providing redundancy for safety reasons.

This means that RTUs can modify their behavior in response to changes in the physical environment, such as when maintenance personnel toggle physical override switches.

For example, an RTU in a water management system might have code to prevent system operators from enabling power to a water pump that's being replaced.

Maintenance personnel should always disconnect equipment they're working on from power and lock it to prevent damage and/or injury.

In fact, this is a crucial safety measure that helps prevent accidents and ensures the system operates safely and reliably.

A remote digital terminal needs a reliable power supply to function properly, and it's good to know that a form of power supply will be included for operation from the AC mains for various CPU, status wetting voltages and other interface cards.

This power supply may consist of AC to DC converters, and in some cases, it can be operated from a station battery system. If AC power fails, the RTU may include a battery and charger circuitry to continue operation, which is especially important for critical applications where a station battery is not available.

RTUs can also drive high current capacity relays to switch power on and off to devices in the field through digital (control relay) outputs.

A power supply is a crucial component of any system, and for Remote Terminal Units (RTUs), it's no exception. A form of power supply will be included for operation from the AC mains for various CPU, status wetting voltages and other interface cards.

This power supply may consist of AC to DC converters, which are used when operated from a station battery system.

In critical applications where a station battery is not available, RTUs may include a battery and charger circuitry to continue operation in the event of AC power failure.

Digital (Status) Inputs are a crucial part of Remote Terminal Units (RTUs). They allow RTUs to read ON/OFF information from the field by checking if a contact, like a switch, is open or closed at the RTU location.

These contacts can belong to various devices, such as electrical breakers, valves, alarms, and machines. They can indicate whether a device is in a certain position or not.

RTUs can also count events, like how many times a contact opens or closes, but this feature is optional.

Digital control outputs are a crucial part of RTUs, allowing them to switch power on and off to devices in the field.

RTUs drive high current capacity relays to a digital output (or "DO") board, which switches voltage to the coil in the relay.

This action closes the high current contacts, completing the power circuit to the device.

RTUs are used in a variety of industries, including petrochemical refineries and nuclear power plants, where they ensure smooth operation and safety.

In harsh environments, RTUs excel, withstanding high temperatures, chemical exposure, and strong vibrations that might cause other controllers to fail.

Their reliability is crucial in remote and wide-area operations, where they can be the difference between system failure and smooth operation.

PLCs are designed for local use in automated manufacturing and excel at controlling devices like pumps, motors, and valves through high-speed, wired connections.

PLCs require complex programming languages such as Ladder Logic or Structured Text, which necessitate specialized skills.

RTUs, on the other hand, are built for monitoring remote locations over large areas and rely on wireless connections to communicate with the devices they oversee.

RTUs can often be programmed through a straightforward web interface, eliminating the need for specialized software.

PLCs operate locally, whereas RTUs can operate remotely, making them ideal for applications where local infrastructure is limited.

RTUs are used in a variety of industries, including petrochemical refineries, where they ensure smooth operation and safety in oil processing. They're also crucial in nuclear power plants, monitoring critical systems in high-stakes environments.

In harsh environments, RTUs excel where other controllers might falter due to high temperatures, chemical exposure, or strong vibrations. They're built to endure dust, high pressure, and other challenging conditions.

RTUs play a vital role in remote operations, allowing businesses to achieve reliable monitoring and control. This ensures systems run smoothly and efficiently.

RTUs support various function groups, including communication functions, acquisition and primary data processing functions, and control functions. They also provide local operators with complete technological, operational, and diagnostic information about the object.

Here are the primary functions of RTUs:

RTUs support communication functions, acquisition and primary data processing functions, and control functions. All communication processes occur in parallel and independently of each other.