and the blanking distance or blocking distance is used to ignore an extended nozzle that would otherwise cause a reflected signal at the top of the probe and result in a high level reading even when no product is in the vessel
and the Level offset is used to correct the level output of the transmitter to match the actual level in your tank or vessel.There are two cases when Level Offset can be used. One is to accommodate for a unmeasurable length at the bottom of the probe (a negative offset) The other is to accommodate for the length of the probe being shorter than the actual depth of the tank (a positive offset).
seems confusing but I will make it clear, if physical dip tape or gauge measures 1200 mmwc and transmitter is showing 1000 then put level offset as +200 mmwc
and if physical dip tape or gauge measures 1200 mmwc and actual level is 1400 mmwc then put level offset as -200mmwc then the transmitter display will show 1400-200=1200 mmwc which matches with physical reading……………..means this is a trick provided by the company to match physical reading with transmitter reading