How do I know what modbusi address to use?

Point your browser to http://example.com/modbus.html to see a full list of available addreses. (Where example.com is the module web address.)

Floating point IEEE values can be displayed by taking the normal address, multiplying by 2, and adding 8000 hex (32768 decimal). For example, the process variable (measured input value) can be seen as a signed integer at address 0001h and as a floating point value at 32770 or 8002h.
The IEE value is automatically scaled to the correct resolution.