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Introduction by Instrument Network: Trends in display instruments (1) Display and recording methods. There are a variety of display methods; in addition to the traditional pointer type, there are LCDs, light-emitting diodes (LEDs), fluorescent digital tubes, as well as fluorescent strips, and color CRT monitors, ultra-thin (TN) VGA color LCD monitors, and more. Recording methods include recording on fiber paper, using a thermal head to record on thermal paper, and printing with colored ribbons. There are also electronic methods for data storage and recording, such as through ICRAM cards and disks. Today, a single display recorder often includes two or more recording modes to meet various needs. (2) Input signal, input channel, and recording channel. The versatility of the input signals has been enhanced; almost all display and recording instruments with microprocessors, both domestically and internationally, can directly accept signals from field sensing elements (sensors) and transmitters, such as various thermocouple and thermal resistance signals. The signal range for thermocouples and thermal resistors can be set arbitrarily; the range for DC voltage signals is from 1 to 500 mV, while the range for DC current signals is from 1 to 500 mA. Various display and recording instruments come with input options as well as multiple recording channels to choose from. (3) Measurement accuracy and sampling period. High measurement accuracy and fast sampling cycle. The measurement accuracy has reached the 0.05 level in some cases, and generally it is at the 0.1 and 0.2 levels. The recording accuracy can reach up to the 0.1 level in some cases, but it is usually at the 0.25 and 0.5 levels. The minimum time required to sample all channels once is 0.1 s (for 6 channels or less) and 1 s (for more than 6 channels). (4) Computational ability. It generally possesses dozens of calculation functions such as addition, subtraction, multiplication, division, ratios, square roots, channel/group averaging, calculation of mass flow rate, steam flow rate, etc., as well as nonlinear processing, automatic correction, and automatic diagnosis functions. (5) Baud rate and control functions. The Pari alarm function can be configured as needed, offering alarms for absolute high/low values, deviations, increasing/decreasing rates of change, and digital status. During alarm reporting, the panel indicates the alarm information recorded on paper or in electronic data storage; multiple sets of relay outputs can also be used to indicate the alarm status. Display instruments with microprocessors utilize software to implement control functions. In addition to conventional on-off control and PID control strategies, program control, PID tuning, adaptive PID, and expert systems are also incorporated, giving it control capabilities similar to those of digital controllers. (6) Electronic data storage. Data can be stored on disk for preservation or future analysis; it can also be stored on an ICRAM card. (7) Operation. Convenient human-computer interaction window. Operation via screen menus or screen graphical interface buttons. At the same time, parameter setting, configuration, calibration, and other operations can also be performed on the display recorder using specialized handheld controllers or a host computer. (8) Virtual display instrument. Multimedia technology is used to replace actual instruments with personal computers. Source — Instrument Network