A201SR04 01A201S12 5880-0009 has an internal reference voltage, both pin 4# (REF) is 4.096V, so the full range of A/D conversion is 4.096V. and the input signal is 0~5V, so it is necessary to add a stage of op-amps to convert 0~5V to 0~4.096V and then feed it to the MAX187. the P1.3 of AT89C52 is connected to the chip select terminal (CS) of MAX187, and the P1.4 of AT89C52 is connected to the serial select terminal (CS) of MAX187. P1.3 of AT89C52 is connected to the chip select terminal (CS) of MAX187, P1.4 of AT89C52 is connected to the serial clock signal terminal (SCLK) of MAX187, and P1.5 of AT89C52 is connected to the serial data output terminal (DOUT) of MAX187. The analogue sampled values are stored in the memory of the microcontroller and then transmitted to the PLC through the serial port of the microcontroller.

A201SR04 01A201S12 5880-0009 A 12-bit D/A converter chip, MAX531, is used to implement the digital-to-touch conversion. We connect an operational amplifier to the output of MAX531 to adjust the analogue output to 0-5V, and the hardware circuit of the output part is shown in Figure 3. Here, MAX531 is a 12-bit serial D / A, with high conversion speed, MAX531 has an internal reference voltage, both 10 # pin (REFOUT) for 2.048V, so the full range of D / A conversion for 2.048V.