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SHEETDESCRIPTIONDESIGN DATE EDIT
01 Mutai Newl
re
istered
TITLE: Additional explanation of
PROFIBUS-DP Master function
(I/O Module Assignment function)
B-62924EN/04-1
FANUC LTD.
02.10.7
DRAW.NO.
Relation with ladder program
The refresh processing of PROFIBUS DI/DO data does not synchronize with the
processing of a ladder program. (Without relation to the processing of a ladder program,
the refresh processing of PROFIBUS DI/DO data is executed.)
Thus, the following cautions should be considered for the development of a ladder
program.
CAUTION
Data simultaneity within one command of a ladder program is
guaranteed on the conditions of the previous section.
But even while a ladder program works, the DI/DO data updating of
PROFIBUS is executed regardless of a ladder program running.
Thus, a ladder programmer should consider the following points.
- When a certain PROFIBUS input signal which is set to the
specified R address is read by the two position of a ladder
program, and even if the ladder program can run within one scan
time, it is not guaranteed that the same value can be read.
The second ladder command may read the different value from
the one of the first.
- When a ladder program writes the data of PRFIBUS output signal
into the specified R address, its signal may be transferred to the
slave before a ladder program runs until the end.