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37  FUNCTIONS
37.9  Safety Diagnostic Function
37.9 Safety Diagnostic Function
The following table lists the safety-specific diagnostic functions among the self-diagnostic functions for the SIL2 Process CPU.
*1 Self-diagnostics is performed in both the SIL2 Process CPU and SIL2 function module.
37.10 Safety Data Identify Check
This function checks if the project data created using the engineering tool and the data in the SIL2 Process CPU are the 
same, and confirms that the program executed in SAFETY MODE is the one written by the user.
This function allows the user to inspect whether the files in the engineering tool and the SIL2 Process CPU match or not.
[Online]  [Safety PLC Operation]  [Check Safety Data Identity]
For details, refer to the following.
 GX Works3 Operating Manual
Item
*1
Description Diagnostic timing Error code
Memory diagnosis RAM diagnosis Detects errors occurring at program memory, 
device memory, and memory used by the system.
• At powering off and on
• At reset
• At END processing
3C20H, 3C21H, 3C22H, 
3C2FH, 3C33H
F/W diagnosis Diagnoses whether the firmware stored in the 
ROM is corrupt.
• At powering off and on
• At reset
3C10H
Program diagnosis Operation circuit 
diagnosis
Detects errors at operation circuits used to 
operate safety programs.
• At powering off and on
• At reset
• At END processing
3C15H
File verification Detects errors in stored safety programs and 
safety parameters.
• At powering off and on
• At reset
• At END processing
2180H, 36E1H, 3C33H, 
3C34H
Diagnoses whether safety programs and safety 
parameters stored in both the SIL2 Process CPU 
and SIL2 function module are the same.
• At powering off and on
• At reset
2180H, 3640H
Operation result 
verification
Output data 
verification
Verifies output results calculated in the respective 
SIL2 Process CPU and SIL2 function module.
At safety cycle processing 3E60H
System diagnosis Time monitoring Monitors the execution status of the respective 
SIL2 Process CPU and SIL2 function module 
processing.
Always 3E61H
Microcomputer 
diagnosis
Detects microcomputer internal register errors. • At powering off and on
• At reset
• At END processing
3C00H, 3C01H
Power supply 
voltage monitoring
Power supply voltage 
monitoring
Detects voltage errors to prevent operation with 
voltage outside the guaranteed operating range.
Always 
(Performs a shutdown.)
Power supply voltage 
monitoring/shutdown 
circuit diagnosis
Monitors whether the circuit monitoring the power 
supply voltage and circuit used to perform 
shutdown are functioning properly.
• At powering off and on
• At reset
• At END processing
3E10H, 3E11H
Reset circuit 
monitoring
Reset circuit 
monitoring diagnosis
Diagnoses whether the reset has been performed 
correctly.
• At powering off and on
• At reset
3E12H
Clock stop 
detection
Clock diagnosis Detects clock errors (frequency errors). • At powering off and on
• At reset
• At END processing
3C16H
CRC calculation 
circuit diagnosis
CRC calculation 
circuit diagnosis
Diagnoses whether the CRC calculation circuit is 
capable of correctly calculating CRC.
• At powering off and on
• At reset
• At END processing
3E01H
Module Module OS diagnosis Verifies whether the SIL2 Process CPU and SIL2 
function module are functioning normally without 
running out of control.
• At powering off and on
• At reset
• At END processing
3C11H, 3C17H