I saw this error 5 years ago with a 5555 Controller. But I didn't get an error message like this in the Rslgx5000 software. I just found out that the serial port was set up to "system" instead of "user". I changed it, closed the dialog box. When I reopened it, the setting was back to "system". I used Firmware 7 at this time. I've shutted down a running production line, rewired over 10 hours for a new project and one controller didn't work because of this error. It tooks me 3 hours to end up with the L5K-export-import solution, here it was the first time I saw the error message. The program was uploaded from another controller, this controller was still running with the wrong value (0), this could be tested by uploading this program again and exporting this to L5K. The "Tokenholdfactor" was not available in the RsLgx5000 Software, but there was already a SSV available. I don't know how a value could change that is not available for the user (we had no SSV instruction for this in the program). We received a non ASCII byte string in this aplication. I assume that a certain byte combination caused the processor to change this setting. The recommendation of the Rockwell support was only to update to a newer firmware.