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33  FUNCTIONS
33.3  Safety Diagnostic Function
33.3 Safety Diagnostic Function
The following lists self-diagnostic functions specific to the Safety CPU.
*1 Self-diagnostics is performed in both Safety CPU and safety function module.
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.
• When power is turned off and 
on
• When the CPU module is reset
• When END processing is 
performed
3C20H, 3C21H, 
3C22H, 3C2FH, 
3C33H
F/W diagnosis Diagnoses whether the firmware stored in the 
ROM is corrupt.
• When power is turned off and 
on
• When the CPU module is reset
3C10H
Program diagnosis Operation circuit 
diagnosis
Detects errors at operation circuits used to 
operate safety programs.
• When power is turned off and 
on
• When the CPU module is reset
• When END processing is 
performed
3C15H
File verification Detects errors in stored safety programs and 
safety parameters.
• When power is turned off and 
on
• When the CPU module is reset
• When END processing is 
performed
2180H, 36E1H, 
3C33H, 3C34H
Diagnoses whether safety programs and safety 
parameters stored in both the Safety CPU and 
safety function module are the same.
• When power is turned off and 
on
• When the CPU module is reset
2180H, 3640H
Operation result 
verification
Output data 
verification
Verifies output results calculated in the Safety 
CPU and safety function module.
When executing safety cycle 
processing
3E60H
System diagnosis Time monitoring Monitors the execution status of the respective 
Safety CPU and safety function module 
processing.
Always 3E61H
Microcomputer 
diagnosis
Detects microcomputer internal register errors. • When power is turned off and 
on
• When the CPU module is reset
• When END processing is 
performed
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.
• When power is turned off and 
on
• When the CPU module is reset
• When END processing is 
performed
3E10H, 3E11H
Reset circuit 
monitoring
Reset circuit 
monitoring diagnosis
Diagnoses whether the reset has been performed 
correctly.
• When power is turned off and 
on
• When the CPU module is reset
3E12H
Clock stop 
detection
Clock diagnosis Detects clock errors (frequency errors). • When power is turned off and 
on
• When the CPU module is reset
• When END processing is 
performed
3C16H
CRC calculation 
circuit diagnosis
CRC calculation 
circuit diagnosis
Diagnoses whether the CRC calculation circuit is 
ca
pable of correctly calculating CRC.
• When power is turned off and 
on
• When the CPU module is reset
• When END processing is 
performed
3E01H
Module Module OS diagnosis Verifies whether the Safety CPU and safety 
function module are functioning normally without 
running out of control.
• When power is turned off and 
on
• When the CPU module is reset
• When END processing is 
performed
3C11H, 3C17H