Failure Point Detection - Omron CJ2 CPU UNIT SOFTWARE User Manual

Precautions for Correct Use Precautions for Correct Use
To clear fatal and non-fatal system errors simulated by executing FAL(006) and FALS(007)
instructions, use the same methods as for actual system errors. For information on how to clear
errors, refer to Section 6 Troubleshooting of CJ2 CPU Unit Hardware User's Manual (Cat. No.
W472). All system errors simulated with FAL(006) and FALS(007) can be cleared by cycling the
power supply.

10-7-10 Failure Point Detection

The FPD(269) instruction performs time monitoring and logic diagnosis. The time monitoring function
generates a non-fatal error if the diagnostic output isn't turned ON within the specified monitoring time.
The logic diagnosis function indicates which input is preventing the diagnostic output from being turned
ON.
Time Monitoring Function
FPD(269) starts timing when it is executed and turns ON the Carry Flag if the diagnostic output isn't
turned ON within the specified monitoring time. The Carry Flag can be programmed as the execution
condition for an error processing block. Also, FPD(269) can be programmed to generate a non-fatal FAL
error with the desired FAL number.
When an FAL error is generated, a preset message will be registered and can be displayed on the CX-
Programmer. FPD(269) can be set to output the results of logic diagnosis (the address of the bit pre-
venting the diagnostic output from being turned ON) just before the message.
The teaching function can be used to automatically determine the actual time required for the diagnos-
tic output to go ON and set the monitoring time.
Logic Diagnosis Function
FPD(269) determines which input bit is causing the diagnostic output to remain OFF and outputs that
bit's address. The output can be set to bit address output (PLC memory address) or message output
(ASCII).
If bit address output is selected, the PLC memory address of the bit can be transferred to an Index Reg-
ister and the Index Register can be indirectly addressed in later processing.
If the message output is selected, the bit address will be registered in an ASCII message that can be
displayed on the CX-Programmer.
FPD(269) execution
condition
A
Logic diagnosis
execution condition
B
CJ2 CPU Unit Software User's Manual
Control data (FAL 004, logic diagnosis output: bit address output)
Monitoring time (0.1-s units): 10 s
First register word (Diagnostics output destination)
Carry Flag
Error-processing block
C (Diagnostic output)
10 CPU Unit Functions
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