I / O modules
PLC interface with the electrical circuit, the input and output section by the (I / O) completion. I / O modules with integrated PLC's I / O circuit, the input signal status register reflects the input and output points to reflect the state of the output latch. The programmable logic controller input module signals into the electrical signals into digital PLC system, the opposite output module. I / O into the digital input (DI), digital output (DO), analog input (AI), analog output (AO) and other modules. Switch means that only the opening and closing (or 1 and 0) signals, analog two states refers to continuous change. Commonly used I / O classified as follows: Switch: Press voltage level points with 220VAC, 110VAC, 24VDC, by isolating way points, with relay isolation and transistor isolation. Analog: divided by signal type, there is a current type (4-20mA, 0-20mA), voltage type (0-10V, 0-5V, -10-10V), etc., according to the accuracy of points, there are 12bit, 14bit, 16bit, etc. . In addition to the general Plc analog input output module purpose IO, there are special IO modules, such as thermal resistance, thermocouple, pulse and other modules. Press the I / O module specifications and determine the number of points, I / O modules can be more or less, but its maximum number of CPU capacity can be managed by the basic configuration, namely by the largest floor or rack slot limit.