Try 44102
To understand Modbus, you have to understand Modicon addressing, Modbus function codes, and Modbus registers.
The underlying protocol uses function codes and register offset to read/write various registers. For example, to read register number 100 in the integer table, you would use function code 3 with an offset of 100. To write to the same register, you would use function code 6.
Modicon addressing is a way to refer to these registers without having to deal with function codes. The first digit in a Modicon address indicates the register memory space. The number after the following digit indicates the register offset. To make things confusing, the first register of Modicon addressing starts with 1, but Modbus starts with 0.
So now lets say you want to access the register mentions above with a Modicon style address. Since it is an integer, the first digit will be 4. The register number is 100, which is really the 101st register. So the Modicon address will be 40101
Note the first digit is really independent of the rest of the address. So 40101 references the same register as 400101
If your documentation says it is register 4101 (assuming it is decimal and not hex), then you add 1 to that and prefix with a 4, therefore making 44102
