2-wire transmitter embedded two-wire passive 4-20mA intelligent control LED digital display meter: SY LED3 series
SunYuan SY LED3 type low-cost, small volume four-position two-wire passive intelligent loop 4-20mA current (LED) digital display meter, using passive design of the input and output of the two wires in series to access the transmitter 4-20mA loop, can be passed through the loop 4-20mA analog, according to the set range of linear correspondence to the decimal digital display. SY LED3 digital display meter adopts two-wire passive working principle, the electrical signal passed in the measuring circuit is not only the input signal of the display meter, but also the power supply of the display meter, this two-wire passive mode of operation does not need other auxiliary power supply, so it is easy and convenient to use the wiring, with small volume, high precision and low cost. The traditional analog display meter adopts potentiometer adjustment, which has a single adjustment parameter, is not flexible and is greatly affected by temperature. Compared with the traditional analog display meter, this digital meter adopts two-key operation and is controlled by the CPU of the central processor, which can realize the setting of various parameters such as zero point, full scale, decimal point, alarm, time delay and so on, and has strong flexibility and practicability. Digital display meter adopts LED display board, LED each segment adopts constant current driver, so that the 4-20mA range of brightness uniformity, and with reverse, over-current protection, suitable for industrial sites, petrochemical, environmental monitoring, mining industry on temperature, pressure, flow, level and other physical quantities of the control point of the monitoring. In most applications, it is through a variety of related sensors will be temperature, pressure, flow, level and other physical quantities into 4-20mA signal, and then access to the SY LED3 digital display, temperature, pressure, flow, level and other physical quantities of real-time display, to facilitate the user to carry out a full range of on-site control.
SY LED3 digital display meter is used to measure 4-20mA DC current signal without external power supply directly on the 4-20mA loop signal to take power measurement. The displayed figure is not the direct current measurement value, but the preset value of 4mA and 20mA, and the measured current value is linearly displayed relative to these two preset values. For example, if 4mA is set to 0 and 20mA is set to 8000, the meter will display 2000 when 8mA is input, and 4000 when 12mA is input; and if 4mA is set to 1000 and 20mA is set to -1000, the meter will display 0 when 12mA is input, and -500 when 16mA is input.The maximum display range of the digital display meter is 9999, which is four digits; the minimum is -1999.
SY LED3 digital display meter also has an alarm function with two isolated switching outputs for local display, control and alarm. This function is only realized from the program, 2 PC452 photocoupler pads position is reserved, to be installed when the user has the need for alarm. The digital display meter sets two alarm points with positive and negative alarm direction settings. The alarm object of the alarm point is for the display reading, the last decimal point of the LED panel blinks when the alarm is on, and the alarm information can be output through the port to drive the optocoupler's alarm signal.
SY LED3 external dimensions: Ф47.6/38.0 × 16.6 mm (large diameter/small diameter × thickness), the use of flame-retardant plastic casing, for the display of control instruments or cabinets within the sensor transmitter signals of the digital display.
Precautions
1. Do not connect the input signal (current direction) inversely, otherwise the digital display meter will be easily damaged.
2, the input current signal is generally not more than 25 mA, when the input current reaches 100 mA, the digital display will be irreparable damage.
When testing or accessing the current circuit, it is better to connect more than 200Ω resistors in series to protect the circuit.
3, can not be used in the humid and corrosive gas environment, otherwise it will reduce the service life or completely damaged.
