Omron CVM1D Operation Manual page 350

Special Instructions
Time Monitoring
1, 2, 3...
Execution condition
for FPD(177)
Diagnostic output
CY (A50004)
Logic Diagnosis
the input in the instruction block that is preventing an output from being turned
ON.
FPD(177) can be used in the program as many times as desired, but each must
use a different D even if the same message is being output.
The following diagram illustrates the type of program section that can be diag-
nosed with FPD(177). The instruction block that is diagnosed by FPD(177)
starts at the fist LD after FPD(177) (excluding LD for TR bits) and ends at the
next output or special (right-hand) instruction (except for OUT for TR bits).
The program sections marked by dashed lines in the following diagram can be
written according to the needs of the particular program application. The proces-
sing programming section triggered by CY is optional and can used any instruc-
tions but LD and LD NOT. The logic diagnostic instructions and execution condi-
tion can consist of any combination of NC or NO conditions desired.
Execution
condition
Logic
diagnostic
instructions
When the execution condition is OFF, FPD(177) is not executed. When the exe-
cution condition is ON, FPD(177) monitors the time until the diagnostic output is
executed with an ON execution condition. If this time exceeds T, the following will
occur:
1. An FAL(06) error is generated with the FAL number specified in the first two
digits of C. If 00 is specified, however, an error will not be generated.
2. The CY Flag (A 50004) is turned ON. An error processing program section
can be executed using the CY Flag if desired.
3. If bit 15 of C is ON, a preset message with up to 8 ASCII characters will be
displayed on the Programming Device along with the bit address mentioned
in step 2.
The following chart shows the timing that occurs when the execution condition
for FPC(177) turns ON.
Monitoring time
Error detected
FPD(177) also searches for the input condition that is responsible for the diag-
nostic output not turning ON and outputs diagnostic results and, if specified, a
message. The following instructions are examined: LD (excluding LD for TR
bits), LD NOT, AND, AND NOT, OR , and OR NOT. Operands addressed indi-
(177
Branch
FPD C
(CY Flag)
A500
04
Processing after
error detection.
Monitoring time
Error not detected because
diagnostic output turned
ON during monitoring time.
Section 5-27
T D
Diagnostic
output
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