Tag: plc

In PLC control system, we mostly use DC proximity sensors. And in DC circuit, the proximity sensors used include 2-wire proximity sensor, 3-wire proximity sensor and 4-wire proximity sensor. And they can be further divided into NPN type and PNP type. Generally, people in the United States and Japan usually use NPN proximity sensor, while in the Europe use the PNP proximity sensor.
The difference of NPN proximity sensor and PNP proximity sensor lies in the conduction situation. NPN proximity sensor belongs to the low level conduction and PNP proximity sensor belongs to the high level conduction. In other words, signal of the NPN proximity sensor flows from the load to the proximity sensor, while that of the PNP proximity sensor flows from the proximity sensor to the load.
We will take FX3U PLC and S7-200 PLC as examples to explain how is the NPN proximity sensor and PNP proximity sensor connected to PLC.

In our load cell product pages, when we introducing the load cells, we often say that you can buy a transmitter/amplifier with a customized output signal (0-5V, 0-10V, 4-20mA) to output standard signal to PLC, DCS and other control systems. Then someone will ask us how to connect load cell to plc. Now today we will explain the connection methods of load cell in details. When forming the weighing and batching control system with PLC, there are four connection methods for load cell.