Defining the I/O Board

what is an i/o board? i/o boards are available in many styles and forms, and they serve the important function in projects and applications of applying the relay effect the primary role of the i/o board is to activate a relay based on an input, and in this role, you have a low voltage actuating a higher voltage i/o boards enable low voltage systems to interact with high voltage systems since embedded devices operate at both dc voltage far below what is needed to actuate i/o boards can be completely electronic with no mechanical aspect to them, but for the purpose of the introduction, we will be focusing on an i/o board with the relay effect being put into action i/o channels an i/o channel is the combination of an input, the actuator, and then the output a transistor can be usedeither to drive the transistor or as the actuator depending on the requirement in the diagram below, the functional blocks of the channel are detailed input the input may be via an opto isolator, a darlington driver, or a similar implementation this side of the process, is the low voltage side, and may switch from 3 3 vdc to as high as 24 vdc depending on the application requirement the role here is to provide a buffer or translator between the low voltage and high voltage side an opto isolator, using the small integrated led, provides the input or trigger to switch the higher voltage, which may be 5vdc actuator the actuator is the step that processes the receipt of the input signal as an example, an optocoupler when the led illuminates, switches the integrated transistor the transistor then switches the higher voltage depending on the requirement, the actuator may be a microcontroller where rules are being processed based on the input this is an advanced topic and will be discussed in a later article relay the final step in the process is the activation of the relay coil when the input requirements have been met, the voltage is then applied to the coil (which is omnidirectional), and the relay activates relays have three contacts a common, a normally open, and a normally closed when the relay is not activated, the contacts is sitting in the normally closed position by connecting wires to the common and normally closed you have a closed circuit as soon as you activate the relay, the internal contact moves, opening the normally closed breaking that circuit and closed the normally open circuit it stays in this position so long as the coil remains active or its latched when the power is removed from the coil, the coil de energises and the internal contact returns to its original position when to use i/o boards are used in applications where the requirement is for a low voltage system to activate a high voltage system; it acts to translate the action of providing an input to a system the low voltage system may be a switch or an mcu output and this in turn actuates the high voltage side of the system learn more about this in the next article