How to read MODBUS register

[songl1993]

Hi I'm trying to read a value using TCP/IP MODBUS, and the register number is 0FFDH. I put the start address as "0" just to test it, and got "illegal function". Then I put in 255 (decimal value of 0FF), and still got "illegal function".
 
What kind of input value do you accept for the start address on MODBUS CLIENT?

Thank you,

[support]

0x0FFD = 4093
If that doesn't work try +1 and -1, i.e. 4092 and 4094

Register addresses can be 0 based or 1 based, depending on Modbus device, hence try the addresses either side of 4093

Hope this helps