6DS4, also known as 6-Digit Serial 4, is a serial communication protocol developed by Omron for use in industrial automation systems. It is typically used in factory automation, process control, robotics and security systems. This protocol uses prefixed and variable-length data frames to transfer information. The 6-digit serial number is a unique identifier that allows the controller to process commands and data. It has features such as time stamping, CRC error checking and data segmentation. It enables reliable and secure data transfer between control systems over long distances or between multiple PLCs. 6DS4 is widely used in applications such as automotive, aerospace and energy sectors.