64SD1-08KRF1-13 Improve on-site input

64SD1-08KRF1-13 Improve on-site input

To improve the reliability of on-site input to PLC signals, the first step is to choose transmitters and various switches with higher reliability. 64SD1-08KRF1-13 prevents various reasons from causing short circuits, open circuits, or poor contact in the transmission signal line. Secondly, add a digital filtering program during program design to increase the credibility of the input signal. 64SD1-08KRF1-13 adds a timer after the on-site input contact, and the timing time is determined based on the contact shaking situation and the response speed required by the system, usually in the tens of milliseconds. This can ensure that the contact is indeed stable and closed before other responses occur. Analog signal filtering can be achieved using the program design method shown in Figure 2b, which continuously samples the on-site analog signal three times. The sampling interval is determined by the A/D conversion speed and the rate of change of the analog signal. The three sampling data are stored in data registers DT10, DT11, and DT 12 respectively. After the last sampling is completed, the maximum and minimum values are removed using data comparison, data exchange instructions, and data segment comparison instructions. The intermediate value is retained as the result of this sampling and stored in data register DT0.

64SD1-08KRF1-13 can also improve the reliability of reading PLC field signals by utilizing the characteristics of the control system itself and the relationship between signals to determine the credibility of the signals. If liquid level control is carried out, as the size of the storage tank is known, the opening and pressure of the inlet or outlet valves are known, and the approximate range of liquid level change in the tank over a certain period of time is known. If the data sent by the liquid level gauge to the PLC is significantly different from the estimated liquid level height, it is possible that the liquid level gauge is faulty. The fault alarm system is used to notify the operator to check the liquid level gauge. For example, each storage tank has upper and lower liquid level limit protection. When the switch is activated, a signal is sent to the PLC. Is this signal true and reliable? When designing the program, we compare this signal with the liquid level gauge signal of the tank. If the liquid level gauge reading is also at the limit position, it indicates that the signal is true; If the reading of the liquid level gauge is not at the limit position, it is judged that there may be a malfunction of the liquid level limit switch or the transmission signal line. Similarly, the operator is notified through the alarm system to handle the fault. Due to the use of the above methods in program design, the reliability of input signals has been greatly improved.