Review on Taidacent Industrial Detection Measurement RS485 5V by John Swain

When it comes to absolute accuracy, you should know that you have to manage it yourself. The dB value MAY approach the lower limit, but again I'm not sure. I have the 5V TTL version and it's in a package that literally touches the Arduino Pro MINI board - I find it utterly amusing that a protocol like MODBUS would be used to allow communication between two devices over a Allow 3-4 inch cables, heh. If you're using Arduino, DO NOT use what appears to be "official library" - it's only for specific development boards.