If we are using function code 01 for reading Booleans and from slave side address given 40010, then what will our starting address be 10 or 10*16? and also when we writing coils?

 

Coils are simply numbered consecutively from 0 to 65535 (or 1 to 65536, depending on whether you start counting at 0 or 1).

If you are using 40010 to mean holding register 10, then your question is about whether the device you are dealing with is "overlaying" coil addresses on register addresses and "packing" coils into registers. If that is the case, it is up to the device manufacturer as to how they do that. Typically, I would expect 16 coils to be packed into each register, but there is no absolute requirement for the manufacturer to do that. You need to consult the device documentation for details on that.

I have a brief explanation at the following web site that might help you with this:

http://mblogic.sourceforge.net/mbapps/ModbusBasics-en.html