Internet PLC Forum

I have a system with two identical AB Controllogix processors, 1756-L1, v. 13.27.  I need to change Channel 0 to user mode.  I had no problem with the first unit, I could change the serial port setting on line, no problems.  On the second unit, after I change the serial port setting, and close the window, I receive an error "Invalid Attribute Value", and my setting are discarded, reverting to the original.  I have check the baud rate, etc, and the user protocal setting, they match the first unit.  Called AB tech support yesterday, but received no solution.  I can change the settings on the offline program, but when I download, the settings are rejected.

Thanks for any help in getting me out of this warehouse and back to my family.

Ken