Mitsubishi Electric MELSEC Q Series User Manual page 451

8 DEDICATED INSTRUCTION
[Operation at execution of WFREAD instruction]
Error
Program example
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When the WFREAD instruction is completed, the completion device (bit device) set in
((D2) + 0) turns on in the END processing of the completed scan, and turns off in the
next END processing.
When an error occurs, the completion device set in ((D2) + 1) turns on and an error
code is stored into the completion status (word device) set in ((S) + 1).
Sequence program
WFREAD instruction
Completion device
Completion device +1
When the dedicated instruction is abnormally completed, the abnormal completion
signal ((D2) + 1) turns on and a corresponding error code is stored into the completion
status ((S) + 1).
Check the error status according to the error code and take corrective action.
Refer to Section 9.3 for the error code.
(1) Program with which the Web server module mounted in the position of I/O
numbers X/Y00 to X/Y1F reads 2 words as binary data from the beginning of the
"ABCD.BIN" file in the "/CF/USER/" directory when M28 is turned on.
END
Scan Scan
processing
Instruction execution
OFF
OFF
Read from file
Normal processing
Abnormal processing
MELSEC-Q
END END
Scan
processing processing
ON
ON
When abnormally completed
Execution type
Number of data
to be read
File position
Number of columns
specification
Word unit
File name
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