In the calibration process, we set the offset of the reference voltage so that the raw analog read 500 when the input to the RJ45 port is 1.25 volts. However, the sensor that you are using may still have error due to some components (e.g. resistors and capacitors). Run snmpset command as: snmpset .1.3.6.1.4.1.3854.1.2.2.1.96. i where * is the IP address of your sensorProbe. * is the administrator password. * is the port number where the sensor for which you want to adjust the offset is plugged in. * is the offset value. It should be in a range from 485 to 515. Do you have any sensor that is capable of reading the fluctuation of electricity, and send me reports? Yes, we have a sensor that is capable of monitoring Voltage, Wattage and Amperage. This is our Power Meter Sensor. You can set alerts as with our other sensors so that you can receive a notification when electricity fluctuates beyond a preset threshold. Please see the product section of our web site for more specific information about this sensor