1 Concepts and Uses Digital display meters are electronic instruments used for display. They are currently used in all walks of life and are widely used in industrial PLC data display. The advent of touch screens and their superior prices are impacting the digital display field, but the outstanding position of digital displays cannot be replaced. Because in the complex factory environment, the digital display shines through the LED light tube, making it clear at a glance that the data viewed from far away can be clearly identified and is the favorite of the workers' masters. And the fonts like the touch screen are small and the brightness is not enough.

The advent of the two-wire PLC digital display also opens up the prospect for digital display industrial applications. It eliminates the hassle of using too many ports for ordinary PLC digital displays. It not only concise the hardware connection, but also the software part on the PLC side. Integration is the first choice for engineers to display PLC data.

2 selection digital display is generally used LED digital display, there are LCD liquid crystal display, used as industrial signal measurement, monitoring, control, regulation, transmission, remote communication. When selecting the type, please pay attention to the following issues:

Size: This is a basic question. The digital display should be installed on the cabinet. The overall coordination must be considered. If it is too large, it may not fit. If it is too small, the display number cannot be seen clearly. In addition, the large-scale instrument has a stronger function expansion, and the same functional price may be. Will be expensive, small gauge may have poor function expansion. At present, the international standards for digital display surface boards are mainly: 48*24mm; 48*48mm; 48*96mm; 72*72mm; 96*96mm; 96*48mm; 160*80mm.

Input signal: Measured directly into the instrument's measurement signal, some industrial signals are directly connected to the meter to measure, and some are accessed after conversion, must be clear about the nature of the measurement signal, otherwise the instrument can not be used to buy, or even damaged Instrument and original equipment. To find out the type of signal: current or voltage, AC or DC, whether it is a pulse signal or a linear signal, etc., and also the size of the signal. The name of the instrument is not the same as the input signal. To give a few examples, the input signal is a 0-75mVdc current meter (name is ammeter, the input signal is a voltage signal, because the current through the shunt obtains a voltage signal); the input signal is 0- 10Vdc tachometer (named tachometer, the input signal is a voltmeter, because the frequency converter converts the speed signal into a voltage signal).

Display digits: This is directly related to the measurement accuracy of the digital display. In general, the higher the display digits, the more accurate the measurement, the more expensive the price, mainly the following: two (99, special); three (999, very few); three and a half (1999, ordinary digital displays dominated); four digits (9999, smart digital displays dominate); four and a half (19999); four and three quarters (3999) ; Five and more than five (commonly used in counters, accumulative meters, and high-end meters), users can select several digital displays based on measurement accuracy requirements.

Working power supply: All digital meters need working power, mainly: 220Vac; 110/220Vac; 85-265VAC/CD switching power supply, 24Vdc (usually ordered), 5Vdc (small panel meter).

Function: Generally, it is modular and optional, and the price will be different with the function. Mainly have the following optional functions: Number of alarms and alarm output groups, power supply output and output voltage size and power, transmission output and transmission output type, communication output and communication methods and protocols, for regulating control instruments, More optional features, specific to select a standardized model with reference to the manufacturer's selection spectrum, and communicate with the manufacturer and confirm the correct order before ordering.

Points to note: The measurement accuracy (the smaller the value is, the more accurate), the response speed (the smaller the value is, the faster the response is), the working environment, the temperature coefficient (the smaller the value is, the smaller the influence of the temperature), overload capacity.

Haiyan Jinhan Electronic Technology Co., Ltd. programmable programmable AC/DC digital display instrument, multi-function digital display instrument, multi-function smart instrument, etc. is a new generation product developed by our company using special analog digital conversion chip plus micro-processing control technology. Quoted GB/T 13976-1992 standards and regulations. It is suitable for measuring or indicating alternating current direct current, alternating current direct current voltage for power stations, electrical switch cabinets and all kinds of electrical equipment. It is widely used in the measurement, measurement and control of energy, machinery, chemical industry, light industry and other industries.

Features:

The display magnification can be arbitrarily set at any time through the button operation on the panel, which is very convenient and flexible to use.

Select the measured value of the transmission output, the output is 4 ~ 20mA, 0 ~ 5V, 4 ~ 12 ~ 30mA and other analog quantities are optional.

Optional RS-485 digital communication interface, using standard MODBUS-RTU protocol, can connect 256 different instruments, transmission distance up to 1.2 km.

4, strong combination of functions, intelligent school zero, school tune, high precision, cost-effective.

5, using a computer automatically than the table, more accurate and automatic, convenient and quick.

6, accuracy level: display 0.5%, data communication: 0.2%, transmission output: 0.2%