Level sensor Transmitter

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I have a level sensor and transmitter(4-20mA standard) of Qidian Automation for sensing level of liquid in tank having capacity of 1000 litres. On transmitter it is displayed 0.516 when tank is half filled. How to know the unit in which transmitter is displaying this value?

plcautomationlevelshareedit  follow  flag asked yesterdayJashanjot Kaur1122 bronze badges

• Please confirm if this is your level sensor: AliBaba QDY30A 4-20ma water liquid level sensor transmitter submersible pool water sensor transmitter HK$279.13-HK$581.51 ahqidian.en.alibaba.com/product/62201803469-811272534/…. – tlfong01 yesterday   
• 1looks like 51,6% off full level – Mike yesterday
• The product sheet link includes a very detailed user guide, with communication protocol and how to calculate the depth of sensor using water surface pressure and pressure at the sensor level. Please let me know if you are using the RS485 20mA interface and more details of the interface at your mcu of computer side. Cheers. – tlfong01 yesterday   
• 1Read the data sheet. – Andy aka yesterday
• 1@tlfong01.. For now I dont’t have the model number. Only I can see some values written on transmitter like, Range : 0-5m, Output : 4-20mA, PWR : DC24V, Accuracy : 0.2%FS – Jashanjot Kaur yesterday
• @Jashanjot Kaur, I am 80% sure of the following: (1) Model Number = QDY30A, (2) Communication Protocol = 20mA, (3) Wiring = 2 wires (Red = V+, Black = V-), (4) Range = 0 ~ 5 metres, (5) Power Supply = 24VDC, (6) Accuracy = 0.2% of FS (Full Scale). You need to read very carefully the user guide of the 4 features list above, and also google and/or wiki to know more details about them, / to continue, … – tlfong01 23 hours ago   
• It is important to understand the following: (7) What is measured is the depth/distance between water surface and the submerged sensor (I am only 80% sure). (8) I guess the setup is more or less the following: (9) The sensor is hanged by fixed length string, say 5 metres below the “normal/regular” water surface/level, (10) So the measurement , say when water is drying out, is something like (a) now is x meters below normal/regular water level. Ah, bed time, see you tomorrow. Cheers. – tlfong01 23 hours ago   
• Two references you might find useful: (1) Current loop – Wikipedia en.wikipedia.org/wiki/Current_loop (2) Why use 4-20mA? – TechRentals sites.google.com/a/techrentals.com.au/wiki/Home/applications/…. Happy learning. Cheers. – tlfong01 just now   Edit   

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