Design Support

 

Digital input modules are frequently used in Programmable Logic Controllers (PLCs), Computer Numerical Control (CNC) and Railway Signaling Data Loggers, to detect 24 V or higher voltage Digital Inputs (DI) from sensor transmitters. In some larger PLCs and Data Logger systems, more than 1000 digital inputs detection circuits need to be integrated in one board. Traditional Optocoupler solutions result in high board temperatures (heating up to 120℃ with ambient temp at 58℃), which can lead to reliability concerns. The implementation of high wattage resistors and cooling fans to counter these temperatures add unneeded cost.