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Many people are very strange to the two words analog and switch used in the process of industrial data transmission, and they don't know what they mean. Literally, we don't know what they stand for. In industry, it is often necessary to transmit these two data in order to observe the collected data and the working status of the equipment. There are only two possibilities for a parameter, and if it is not an analog, it must be a switch. Today we will take you to understand what these two terms mean.

So what is analog? What is the switch quantity?

Analog quantity is a continuously changing quantity, such as temperature, from 0100 degrees Celsius, pressure from 0~10Mpa, liquid level from 1m to 5m, opening of electric valve from 0100%, etc., these are all analog quantities.

The switch quantity indicates that the physical quantity has only two states, such as the on and off state of the switch, the closing and opening of the relay, the opening and closing of the solenoid valve, and so on. The state of the switch quantity, or 0 and 1, indicates power on, and 1 represents power off. For example: buttons, switches, time relays, overcurrent pressure relays, which belong to the input and output of contactors, relays, solenoid valves and so on. In other words: the switch is a real object, while the analog is a virtual object, such as drawing on a computer.

For the control system, because the CPU is binary, each of the data has only "0" and "1" states, so the switch value can be represented by a bit inside the CPU, for example, "0" for on, and "1" for off. On the other hand, the analog quantity usually needs 8 to 16 bits to represent an analog quantity according to the accuracy.

The most common analog quantity is 12 bits, that is, the accuracy is 2-12, and the highest accuracy is about 2.5/10000. Of course, in the actual control system, the accuracy of analog signals is also limited by the accuracy of analog / digital converters and instruments, which is usually impossible to achieve such a high level.

The switch value, which includes the input and output, is a digital signal, and there are only 0 and 1 states. The input comes from the contact outside the protection device and is used by the protection device. The output is the contact provided by the protection device to the outside. For external equipment, such as switch tripping, there are only two opposite working states, such as high level and low level, relay coil power on and off, electric shock on and off, PLC can directly input and output switch signal. Some PLC (such as Siemens S7 series) call the switch quantity digital.

The analog quantity, such as PLC, such as voltage, temperature, pressure and rotational speed, can not directly deal with the analog quantity. It is necessary to use the AD converter in the analog input module to convert the analog quantity into a digital quantity proportional to the input signal. Digital quantities in the PLC (such as the output of the PID controller) need to be converted to voltage or current proportional to the corresponding digital by the DA converter in the analog output module for use by an external actuator (such as an electric regulator or frequency converter).

The above is the meaning of switch and analog. The industrial grade Internet of things gateway supports 4 switch input interfaces and 8 analog input interfaces, which can be compatible with a variety of industrial sensor acquisition requirements. In the industrial field, the accurate transmission of switch and analog signals can also enable enterprises to understand the changing process of collected data and the operation of equipment in real time and accurately. at the same time, it is conducive to remote management and reduce workload.

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