Anyone got any info on changing a lon io board. I have got a new one and addressed it the same but still won't work. I got a tool and it says the sub net is not valid. There has to be a procedure to replace a board with another board that hasn't been in the system yet. Thanks for the help.

Have you tried pushing the red little test button on the IO board? Then the computer will look at it and it should start working. If that does not work you can also send a command using the LCD screen.