This document is a PID function block usage instruction for Beijing KDN Automation Technology Co., Ltd.'s KDN-K3 series PLC. It describes the functionality of PID control and the usage methods of manual mode and automatic mode.
The document provides detailed instructions for using the PID function block in Kaidian KDN‑306 PLCs. It describes the available input and output variables, the structure of the PID block, and the logic for manual and automatic control modes.
Key sections include a list of 12 input variables and 2 output variables, the formulas for normalization and output scaling, and a practical example that controls a heater using a 4‑20 mA signal. The example shows how to map PLC internal values (1000‑5000) to an analog voltage range of 1‑5 V. This manual is written in Chinese.
| Maximum simultaneous PID blocks | 6 (data memory must be distinct) |
|---|---|
| Number of input variables per PID block | 12 |
| Number of output variables per PID block | 2 |
| Output range for XOUT | 0 to 1 |
| Analog output voltage range | 1 V to 5 V (PLC value 1000‑5000) |
In manual mode AUTO is set to 0, and the input variable XO is passed directly to XOUT (range 0‑1); other inputs are ignored.
When AUTO is 1, the difference between SP and PV is normalized using the linear formula Y = K·X + B before PID calculation.
Up to six PID blocks can be used simultaneously, provided each block has a separate data memory area.