Thanks Godra,
I try to click a button and change one bit of the plc:40001, lets say bit 2.
so I create an odometer and the PLCaddress =40001, also PLCaddressKeyboard = 40001; (I can click on it and modify the values but I want to use a button, not with the keypad)
when I click on a button, I will use odometer.value OR 0000010 (bit 2) and somehow send to odometer, and directly trigger the odometer.write.
In this way I can change a bit of PLC:40001, instead of using ModbusTCP function 22, bit mask write. However, I don't know how to write this program.