For any digitally monitored or automated equipment, controllers interact with physical sensors and output devices using electronic input/output (I/O) signals. Equipment of all types needs I/O systems able to physically connect and functionally interface to a multitude of wired electrical signals. These systems provide seamless connectivity from the field to the controller and support Industrial Internet of Things (IIoT) initiatives.
Depending on the application, designers may use one or more PCs, embedded microcontrollers, programmable logic controllers (PLCs), and/or other components to automate their systems. So many controller choices can lead to a situation where designers must apply numerous types of I/O systems, driving up the design effort, hardware cost, and spare parts requirements. Fortunately, there are remote I/O systems available, based on industry standards, that enable equipment builders to maintain design consistency, simplify work, and increase automation flexibility.
Standardized remote I/O (Figure 1) helps equipment designers in many ways: designers and technicians only need to learn one platform, it avoids costly and proprietary hardware and software, provides more choice for I/O signals, and reduces required spare parts inventory.
For almost any controller, an equipment builder may select — and for just about any discrete or analog field signal conceivable — a standardized remote I/O platform is the right fit.
Because I/O signals can be anywhere on a machine, wiring them back to one centralized location can be cumbersome. Remote I/O enables builders to install I/O modules in logical and convenient locations where groups of points are localized, and then connect them to the controller with a single network cable.
Following are some key remote I/O system requirements:
Compatibility with standard industrial communication protocols
Flexible and scalable architecture arrangements
Compliance with IEC and UL standards
Compact form factors, quick assembly, simple wiring
Variety of I/O modules accepting any signal type
Clear status indication for modules and points
Traditionally, RS-485 serial communication media has been widely used but today, Ethernet is rising to prominence.
In either case, Modbus (RTU and TCP, respectively) is an industry-standard protocol that I/O platforms should support for best interoperability.
Remote I/O systems with gateway or master modules provide the best architectural flexibility and scalability, while compact form factors, snap-in modular assemblies, a wide selection of I/O modules, and industry ratings compliance enable installation where needed. Users should also ensure I/O systems are easy to install and wire, and use push-in wiring for tool-free connectivity and long-term vibration resistance (Figure 2).
Users will find it most convenient if the I/O system can be pre-configured on the workbench with simple software and a standard micro-USB cable. Once installed, LED status lights and marking provisions should be provided to help users commission and maintain the I/O.
Choosing the right standardized remote I/O platform simplifies the task of automating equipment and creating IIoT applications, and provides seamless connectivity between almost any type of field devices and controllers.
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