Omron CP1H-CPU - 05-2006, Operation Manual

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Failure Diagnosis Functions
Section 6-7
6-7-2 Failure Point Detection: FPD(269)
FPD(269) 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 pro-
cessing 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 preventing the diagnostic out-
put from being turned ON) just before the message.
The teaching function can be used to automatically determine the actual time
required for the diagnostic 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 the result. The output can be set to bit address out-
put (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 Register and the Index Register can be indirectly
addressed in later processing.
If the message output is selected, an error message can be displayed on the
CX-Programmer at the same time as a FAL error is generated for time moni-
toring.
Time Monitoring
Monitors whether output C goes ON with 10 seconds after input A. If C
doesn’t go ON within 10 seconds, a failure is detected and the Carry Flag
is turned ON. The Carry Flag executes the error-processing block. Also, an
FAL error (non-fatal error) with FAL number 004 is generated.
Logic Diagnosis
FPD(269) determines which input bit in block B is preventing output C from
going ON. That bit address is output to D1000 and D1001.
C (Diagnostic output)
Carry Flag
(ON for timeout)
Control data
(FAL 004, bit address output for failure)
Monitoring time (0.1-s units): 10 s
First register word of diagnostics output
FPD
#0004
&100
D01000
Error-processing block
FPD(269)
execution condition A
Logic diagnosis
execution condition B