Pressure sensor 17216318 is suitable for VOLVO roller/grader

When choosing the right sensor, different types of machines and programmable controllers need to pay close attention to the details. Almost every modern machine that needs to be repaired or upgraded has very specific requirements for the types of data that must be retrieved. Not only the machine has specific requirements, but also the CPU and module of the control system have their own requirements.

Because of this diversity, there are a variety of sensors available, and each sensor is designed for a very specific job and provides a very specific data configuration. In this paper, the process of selecting the right sensor for different applications will be carefully studied. In particular, the basic knowledge of using machine parameters to determine the type of sensor to be selected, how to identify the required sensor polarity, and how to choose between normally open and normally closed states will be introduced.

Different types of sensor categories

The relationship between the product you are trying to detect and the sensor selection is more important than anything else. Usually, if you find that you have made a wrong choice in these aspects, you can find a programming method or module to reverse the polarity of the signal.

However, if the wrong sensor category is selected, the product may not be detected at all. No amount of circuits can solve this problem.

Sensor polarity

Most digital inputs need to be connected to a DC voltage, usually 10 to 24 vDC. However, some systems can use 120 vAC or sometimes 24 vAC control voltage. These are beneficial in some special cases, because they don't need the complexity of DC power supply and only need a transformer.

These AC sensors are usually not set with polarity, and data sheets usually indicate that loads can be placed on hot wires or neutral power wires, which are usually brown and blue from pre-wired tail harnesses.

The AC sensor should be selected only when the input module of the controller is configured as AC. This is not as common as DC, but this type should be used if the module is designed for 120 vAC input.

Normally open or normally closed

Another difference in sensor selection criteria is to choose between normally open (NO) and normally closed (NC). Within the scope of digital control system, it really makes no difference, as long as the program is written for the appropriate sensor.

The only difference of NO/NC is that if the sensor type is selected to make the sensor circuit open for more than 50% of its life, it can save power. The cost savings may be small, but when the initial cost of the sensor is the same, it is meaningful to choose the most efficient equipment for design.