Feature: 1. High Performance: This product adopts high accurate sensor, which has the characteristics of wide measurement range, good linearity, good versatility, convenient use, long transmission distance.    2. Accurate Temperature and Humidity Acquisition: Temperature acquisition, accurate measurement, the range can reach & 8209;40& 8451; to 80& 8451;. Humidity acquisition, the range can reach 0& 8209;100%RH, and the measurement accuracy is high.    3. Wide CO2 and Pressure Range: CO2 measurement range is wide, there are multiple ranges to choose from. Wide range of 600& 8209;1100HPa pressure range, can be used in various environments. Can measure PM2.5 and PM10 concentrations at the same time.    4. Wide Application: The wall mounted multi element transmitter can be widely used in various environmental monitoring, can monitor a variety of elements, and has a variety of signal output methods.    5. Convenient to Use: 10& 8209;30V DC wide voltage range power supply. It is convenient for use in various environments, safe and reliable, beautiful in appearance, easy to install, and durable.       Specification:            Item Type: Temperature and Humidity Transmitter      Material: Plastic Weight: Approx. 194g/6.84oz Size: 110x70x38mm/4.33x2.76x1.50in Coding: 8 bit binary Data Bits: 8 bits Parity Bit: None Stop Bit: 1 Error Checking: CRC (Redundant Cyclic Code) Baud Rate: 400bit/s, 4800bit/s, 9600 bit/s can be set, the factory default is 9600bit/s DC Power Supply (Default): 10 to 30V DC Power Consumption: ≤1.2W& 65288;12V DC, 25& 8451;& 65289; Average Current: & 65308;85mA Transmitter Circuit Working Temperature And Humidity: -40& 8451; to +60& 8451;, 0%RH-95%RH non condensing Temperature Measurement Range: -40& 8451; to +80& 8451; Temperature Measurement Accuracy: ±0.5& 8451; Humidity Measurement Range: 0-100%RH Humidity Measurement Accuracy: ±3%RH Air Pressure Measurement Range: 600-1100HPa Barometric Pressure Measurement Accuracy: ±0.5HPa CO2 Measurement Range: 0-5000, 10000ppm& 65288;Default range 0-5000& 65289; CO2 Measurement Accuracy: ±20ppm PM2.5/10 Measuring Range: 0-1000ug/m³ PM2.5/10 Measurement Accuracy: & 65308;read numbers±10%(25& 8451;) Output Signal: 485 signal Stability: & 65308;2%FS Nonlinear: <1%FS Response Time: ≤120S Wiring Instructions: Power Supply: thread color: Brown, instruction: V+; thread color: black, instruction: V- Communication: thread color:yellow, instruction:485A; thread color: blue, instruction:485B Application: Widely used in various environmental monitoring, can monitor a variety of elements, and has a variety of signal output methods, which is convenient for use in various environments, safe and reliable, beautiful in appearance, easy to install, and durable. Common problems and solutions The device cannot be connected to the PLC or computer Possible reason: 1) The computer has multiple COM ports, and the selected port is incorrect.