Bus type digital instrument

Abstract

The invention discloses a bus type digital meter. A present meter can carry out communication with a host computer, such as a computer, and the like, through a serial bus interface, and transmits data to a bus (a computer, and the like), but can not receive or read the data directly from the bus (the computer, and the like), that is, the serial bus interface of the present meter is a communication output interface, and the meter can not directly input and read serial bus data; therefore, one bus type digital meter is needed, which consists of a serial bus input interface, a single chip microcomputer, a digital display, a digital decoder, an address matcher, a digital memory, a controlling keyboard, a power supply and an output interface. The product of the invention is used for a digital control system.

Description

Technical field: [0001] The invention relates to an intelligent instrument, in particular to a bus-type digital instrument in a serial bus input mode. Background technique: [0002] Existing digital display instruments are mainly designed for analog, pulse, and switch input signals. With the development of control methods, the existing input methods cannot meet the development requirements of digital control systems. There are two types of existing instruments according to the bus interface: with digital bus interface and without digital bus interface. Existing instruments without digital bus interface cannot be directly connected to the bus system. The input mode of existing instruments with digital bus interface is Analog input, pulse input and switch input: such as thermocouple, thermal resistance, current signal, voltage signal and square wave pulse, etc. Existing instruments communicate with host computers such as computers through their serial bus interface, and trans...

AI Technical Summary

Problems solved by technology

When long-distance input data is transmitted, the error is large or even distorted. Under the premise of not considering the power supply, each instrument needs at least one two-core shielded cable to transmit the input data signal. When a large number of instruments are used, a large number of cables are required. Not only does it lead to an increase in cable costs, but it also generates a lot of engineering costs, and it is not easy to maintain in the future

[0006] In order to input and receive data output by digital devices such as computers, the method of "computer + code converter + analog conversion equipment + instrument" is generally adopted; that is, the data output by the computer (digital output device) is converted into a serial bus through a code converter The signal is then transmitted to the digital-analog module (D / A), and the digital-analog module converts the signal into an analog signal and inputs it to the existing instrument, and the instrument converts the analog signal into a digital through the analog-digital module (A / D) in the meter The signal is digitally displayed on the instrument, etc. The existing method is not only expensive, but also leads to a decrease in accuracy due to multiple conversions

Images