Distributed I/O places I/O modules closer to sensors and actuators in the field, often with some level of local processing capability. Each node can pre-process signals, execute local logic, and communicate results back to the main controller. As we mentioned earlier Remote I/O is sometimes also referred to as Distributed I/O. These modular devices provide a flexibility distinctly lacking in traditional devices, like Programmable Logic. An optocoupler, also known as photocoupler or opto-isolator, is a device which can transfer an electrical signal across two galvanically-isolated circuits by way of optical coupling. Opto-isolators prevent high voltages from affecting the system receiving the signal. Commercially. There are many different applications for optocoupler circuits, so there are many different design requirements, but a basic design for an optocoupler providing isolation for example between two circuits, simply involves the choice of appropriate resistor values for the two resistors R1 and R2.
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