GE 90-30/20/Micro manual On/Run, Off/Stop, Yes

2

Clearing the Fault Table with the Key Switch

If you turn the key from the RUN to STOP and back to RUN position during the 5 seconds when the RUN light is flashing this will cause the faults to be cleared and the CPU will be placed into RUN mode. The light will stop flashing and will go solid ON at this point. The switch is required to be kept in either RUN or STOP position for at least 1/2 second before switching back to the other position.

Note

If you allow the 5 second timer to expire (RUN light stops flashing) the CPU will remain in its original state, STOP/FAULT mode, with faults in the fault table. If you turn the Key Switch from the STOP to RUN position again at this time, the process will be repeated with this being the first transition.

The following table provides a summary of how the two CPU parameter settings affecting the Key Switch (R/S Switch and IOScan-Stop) and the Key Switch’s physical position affect PLC.

R/S Key Switch		IOScan-Stop
Parameter in CPU	Key Switch	Parameter in CPU
Configuration	Position	Configuration	PLC Operation
OFF	X	X	All PLC Programmer Modes are allowed.
ON	ON/RUN	X	All PLC Programmer Modes are allowed.
ON	OFF/STOP	X	PLC not allowed to go to RUN.
ON	Toggle Key	X	PLC goes to RUN if no fatal faults are present;
	Switch from		otherwise, the RUN LED blinks for 5 seconds.
	OFF/STOP to
	ON/RUN
ON	Toggle Key	NO	PLC goes to STOP–NO IO
	Switch from
	ON/RUN to
	OFF/STOP
ON	Toggle Key	YES	PLC goes to STOP–IO
	Switch from
	ON/RUN to
	OFF/STOP

X=Has no affect regardless of setting

Enhanced Memory Protect with Release 8 and Later CPUs

In the Release 8 and later CPUs, the Key Switch has all the functionality discussed above, plus, by setting a parameter in the programming package, it can be used to protect RAM so that the RAM cannot be changed from the programming software. Two types of operations are blocked when this memory protection is enabled: the user program and configuration cannot be modified and the force and override of point data is not allowed. This is activated through the Mem Protect field in the 350 or 360 series CPUs module configuration screen in Logicmaster. The default is Disabled.

GFK-0467K Chapter 2 System Operation 2-15