Remote IO Panel

FAQs Guide

Data is the foundation of all Industrial IoT. Without data, subsequent visualization and analysis would be impossible. Devices that transmit data to or from computers play a key role in the monitoring and utilization of many key devices and instruments in the industrial control and automation industry. In industrial control systems, I/O (input/output) devices provide interfaces that enable communication between field instruments and control devices. Field instruments may include sensors and actuators, etc., while control devices usually refer to programmable logic controllers (PLCs) or industrial PCs. In short, it is the connection that allows PLCs and other computers to receive inputs from sensors and send outputs to connected devices in the system.

In addition to ensuring field equipment operation, remote I/O modules provide a variety of data to maximize productivity. This technology enables data communication between the central processing unit and remote devices within a wide network. Remote I/O technology is crucial because it helps bridge the gap between data processing units and peripheral devices. It allows devices to be placed far away from the controller, making the system more flexible and scalable, and eliminating the need for extensive and expensive wiring.

In this article, we will go through the basic differences between local I/O and remote I/O, how remote I/O works, the communication protocols, and some of its advantages.

1. How Remote I/O Works

In a remote I/O system, multiple components come together to ensure efficient communication between the central processing unit and peripheral devices. Components such as remote I/O, remote bases, field devices, communication networks, and CPUs or programmable logic controllers can be found here.

At the heart of remote I/O is the exchange of data between a computer’s central processor and a remote device. This data exchange occurs through an I/O module that acts as an intermediary in the communication process, even over great distances. This module is crucial because it acts as a bridge between the CPU and the remote device. It decodes the output signals of the central processor into a format that the peripheral device can interpret, and vice versa.

A remote base is a housing unit for I/O modules. It can usually contain multiple modules and acts as a node for communication between the CPU and remote devices. This base can be rack-based, where different input or output modules are plugged into the rack or distributed in multiple locations.

Field devices, such as sensors and actuators, are devices that provide input to or receive digital output from I/O modules. Sensors are used to collect data from the environment, such as temperature or pressure, and send this data out for processing. Actuators, on the other hand, perform actions based on commands received from the CPU, such as opening or closing a valve.

The communication network facilitates the data exchange between all these components. Depending on the specific requirements of the system, the communication network can be wired or wireless and have different data transmission speeds and protocols.

For a remote I/O system to work, it must rely on the CPU or PLC, which is the brain of the entire system. Inputs and outputs of PLCs can be handled simultaneously. Therefore, these devices are able to read and receive data from the I/O parts of the PLC equipment. These parts may include separate I/O cards as well as fully integrated parts that connect to the PLC hardware. Regardless, the PLC is the device that reads and interprets the data, not the remote I/O system. In addition, the PLC is also responsible for sending commands, while the remote I/O only acts as a way for the data to reach the PLC. Therefore, in many I/O setups, the PLC is located completely different from the I/O card or hardware.

Regardless of where it is located, the PLC must be able to receive data collected by the I/O hardware. Usually, some type of Ethernet protocol or other specialized transmission technology is used to communicate large amounts of information between the remote I/O portion of the hardware and the PLC. Essentially, the remote I/O devices will communicate with the PLC using an adapter module that connects to the backplane of the PLC rack.

2. Types of Remote I/O Systems

In industrial automation applications, there are two main types of remote I/O systems: wired and wireless. The main difference between them is the communication method between the controller and the input or output module.

1). Wired Remote I/O System

Wired remote I/O systems are the traditional form of I/O systems where physical cables are used to connect the I/O modules to the controller. These systems can use a variety of remote I/O protocols such as Ethernet/IP, EtherCAT, Profibus, Profinet, or DeviceNet, among others.

2). Wireless Remote I/O System

As the name implies, wireless remote I/O systems use wireless technology to communicate between I/O modules and controllers. These systems offer unique advantages, especially in challenging environments where wiring is not feasible or cost-prohibitive.

WirelessHART, ISA100.11a, or ZigBee are some of the wireless protocols that can be used in wireless systems. These protocols are designed for industrial environments and have the characteristics of low energy consumption, strong anti-interference ability, and the ability to form a mesh network to improve reliability and coverage.

Having to install an infrastructure is one of the major disadvantages of wired systems. Installing and maintaining network cables can be time-consuming and costly, especially in large industrial plants. In addition, the presence of physical cables can limit the flexibility of the system layout. Wireless systems also have limitations in terms of distance and bandwidth. The maximum communication distance is usually limited by the power of the wireless signal, which can be affected by obstacles and interference. Bandwidth (i.e., the amount of data that can be transmitted per unit time) may also be lower compared to wired systems.

Overall, wireless remote I/O systems offer significant advantages in terms of flexibility, reduced infrastructure costs, and scalability. However, these advantages must be weighed against challenges in reliability, speed, distance, and bandwidth. As with wired systems, the choice of a wireless system depends on the specific needs and environment of the application.

3. Local I/O and Remote I/O

Local I/O usually refers to I/O modules installed in the same cabinet. It can be an I/O module directly connected to the PLC backplane, a PCI/PCIE card installed on a PC, or a USBI/O module used in close proximity. In short, it is often used in small to medium-sized control systems where all components are close together and plays a vital role in fast response time and minimum signal delay. Since centralized management can be achieved, the corresponding layout cost and maintenance cost are much smaller.

Local I/O also has the characteristics of high speed and high channel density. High-speed measurements requiring more than 100K samples/second are usually implemented using local I/O.

I/O modules that are remote from controllers (PLCs/PCs) are usually used to obtain data or send commands from sensors or actuators that are physically far from the controller. Equipment in large industrial plants is often distributed over a wide area, making it difficult to centrally wire. There may also be harsh environments where it is impossible to install a PLC with local I/O modules near field equipment. At this time, the use of remote I/O enables modular and scalable applications, allowing easy expansion by adding more remote I/O modules, greatly reducing the wiring complexity of large engineering equipment and improving installation flexibility.

In summary, remote I/O offers significant advantages in flexibility, scalability, and reduced wiring complexity, making it an ideal choice for large distributed systems. Local I/O may be suitable for small, compact control systems, but its advantages diminish as the size and complexity of the system increases.

4. Communication Protocol of Remote I/O

Data transmission on remote I/O devices usually follows specific protocols, depending on the design of the system and adapter used. These protocols control the identification of the device, the format and sequencing of data, and the detection and handling of communication errors. The protocol we choose depends largely on the support of the device, so it is important to confirm that the controller and remote I/O devices support the same protocol.

Depending on your needs and existing equipment, one protocol may be better suited for a particular task than another. The following is an overview of common communication protocols used in remote I/O systems.

• The EtherNet/IP protocol is used in industrial automation as a way to communicate. It uses standard Ethernet technology to provide high-speed, reliable communication between devices on the factory floor.
• Industrial automation relies heavily on Modbus, which is one of the oldest and most widely used protocols. It is easy to implement and has a wide range of uses.
• Profibus (Process Fieldbus) is another popular communication protocol in industrial automation, especially in process automation and factory automation applications.

Of course, the richness of communication protocols is more than the above items, and more details will not be described in this article.

5. Conclusion

Remote I/O is widely used in today’s industrial field due to its rich functions, diverse designs, and flexible use. It can ensure reliability even under the worst conditions, thereby improving system availability. At the same time, remote I/O systems and distributors also provide a flexible, scalable, and efficient method for controlling and monitoring various processes in the automation of the manufacturing industry. This improves productivity, reduces maintenance costs, and ultimately increases profitability.