What Is a Panel Meter?
A panel meter is a device that displays input signals in digital or analog format.
Today, digital panel meters are the mainstream, and many of them are equipped with functions to convert analog signal output from various sensors. For example, RPM, speed, flow rate, and temperature, in addition to voltage and current, are into digital signals for display, to record them internally, and to communicate with other devices to send and receive data. Many of them are equipped with functions to send and receive data through communication with other devices.
In addition to display panels that use multiple 7-segment LEDs or black-and-white or color liquid crystal displays, some use conventional analog meters.
Uses of Panel Meters
LCD panel meters not only display numerical values, but can also display various types of bar graphs and line graphs, and have a variety of other expressive capabilities.
For example, a digital panel meter for measuring current and voltage in a factory takes in the current and voltage output from various devices at a sampling speed of several thousand times per second. It converts them to digital values and then feeds them into a microcomputer, etc. that controls the system, performs arithmetic processing, and outputs the results on a display panel. The results are output to the display panel.
Principle of Panel Meters
Digital panel meters are often used in factories and other places with severe environmental conditions. They are supported in a wide range of guaranteed operating temperatures from 10 to 50 degrees Celsius and power supply voltages from 100 to 200 VAC, which is different from consumer devices.
Most digital panel meters support RS-232C or RS-485 as a communication interface with external devices. These interfaces are supported for communication with host PCs and other devices.
The communication interface supports a protocol called Modbus, which is commonly used in measuring instruments and other professional equipment.
It accepts commands from the host PC and sends status information to the host side for periodic monitoring of the digital panel meter status, turns the power on and off based on instructions from the host, sends data in the internal register of the digital panel meter to the host PC, and sends data sent from the host to the host. The host PC writes the data sent from the host to the internal register of the digital panel meter.
In this way, the host PC can control up to 31 digital panel meters simultaneously via Modbus.