These display utilise OLED technology (Organic LED technology). OLED displays have a rapid response time, wide viewing angles, exceptional colour rendition and outstanding contrast and brightness display ratios. S401 an OLED indicator with Modbus communication - a HMI panel mount compact device, with a wide range visualization (up to 30 measurements) Programming is achieved via supplied software interfaced to a PC, or from the front keypad / menu. Interfaces to RS485 Modbus Master are as well as RS485 Modbus Slave. S401 has several master functions (27 math functions and 20 readings from slave modules)