Types of PLC input and output modules

Roughly divided into the digital input plc DI, digital output plc DO, analog input AI, analog output AO. Digital inputs and outputs are generally of 24V. Class 2 4 kinds of analog quantity, type 2, respectively, and the current-voltage type. There 0-10V voltage type and -10 to 10V. Current type mainly 4-20MA, 0-20MA. Then the module through A / D converter, converting the analog quantity into a + number between 32767 ~ -32768, and then exercise control