I need help in figuring out why I keep getting major alarm number 1632 that gives the message "F-SAFE MUTUAL DIAG. ERR.(MONITOR)? I am seeing it once or twice a day but only during a specific shift. I am wondering what causes this error. It is on an NX100 controller and it happens at different times when the robot program is running. it happens while the robot welding program is running, and other times it happens when the table sweep program is running. Could this be caused by a faulty safety relay, or an operator breaking the light curtain during the table sweep? I have looked in the error code table in the user manual and I can't even find this error code, so any help would be appreciated.