In engineering applications, we often encounter analog inputs of different signal types, such as voltage and current. The default input type for the EVE EM235 is 0-20mA (0-5V). When selecting transmitters with other ranges, the DIP switches need to be reset, and input calibration must be performed using the OFFSET and Gain potentiometers. Below is a brief introduction to the input calibration of the EVE EM235. I. EVE EM235 Product Introduction The EVE EM235 is a hybrid analog module, with 4 analog inputs and 1 analog output. It can acquire voltage and current signals of different ranges and output voltage signals from -10V to 10V and current signals from 0 to 20mA. The module includes a calibration potentiometer and a range selection DIP switch. See the image below for the product appearance. II. Range and DIP Switch The analog input module can be set to different measurement modes (current and voltage) using DIP switches. The module switch settings apply to the entire module; a module can only be set to one measurement range. Furthermore, the switch settings only take effect after a power cycle. Only one input range and format can be set simultaneously, meaning the same input range and resolution. See Table 1 for details on the input ranges corresponding to the DIP switch combinations. Table 1. DIP Switch Correspondence Table III. Calibration of Yiwei EM235 DIP Switches SW1 to SW6 The factory setting for SW1 to SW6 is 100001 (1 for ON/0 for OFF), corresponding to a measurement range of 0-5V voltage and 0-20mA current. This range is factory calibrated. When users change to other input range modes, they need to recalibrate the input. The calibration method is to calibrate by rotating the OFFset and Gain potentiometers. 1. Main Hardware Requirements A. PC equipped with STEP 7 MicroWIN for data monitoring; B. One USB-PPI or RS232-PPI cable for connecting the PC and PLC; C. One 200 series CPU for configuring the EM235; D. EM235 module to be calibrated; E. A precise signal source to provide voltage or current signals. Note: If there is no signal source, the analog output of the EM235 can be used. 1. Connect calibration voltage M0 to X- (X represents A/B/C/D), and V0 to X+; connect calibration current M0 to X-, and I0 to X+. 2. Specific steps: A. Disconnect the module power supply and select the required input range; B. Connect the CPU and module power supplies and allow the module to stabilize for 15 minutes; C. Use a precise signal source to apply a zero-value signal to one input terminal, or force the EM235 analog output to 0; D. Read the measured value of the appropriate input channel in the CPU; E. Adjust the OFFSET potentiometer until the reading is zero, or the desired digital data value; F. Connect a full-scale value signal to one of the input terminals, or force the EM235 analog output to the maximum value of the input range, and read the value sent to the CPU; G. Adjust the GAIN potentiometer until the reading is 32000, or the desired digital data value; H. If necessary, repeat the bias and gain calibration process.