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File Memory Section 5-1
highest I/O memory address.
When double words are being used, I/O memory data is converted
to ASCII and stored in two-word fields in order from the lowest to
the highest I/O memory address. (Within the two-word fields, the
higher-address word is stored first and the lower-address word is
stored second.)
d) Delimiters:
When there are no delimiters, the fields are packed consecutively
and then stored. When delimited by commas, commas are insert-
ed between fields before they are stored. When delimited by tabs,
tab codes are inserted between fields before they are stored.
When delimiters (commas or tabs) are specified in FREAD(700),
the data is read as delimited data with one-word delimiters (com-
mas or tabs).
e) Carriage Returns:
Data is packed consecutively when carriage returns are not used.
When carriage returns are used, a carriage return code is inserted
after the specified number of fields. An offset from the beginning
of the file (starting read word or starting write word) cannot be
specified in the FREAD(700)/FWRIT(701) instructions if carriage
returns are used in the file.
f) Number of Fields:
The overall amount of data in the file depends upon the number of
fields (number of write items) specified in the FWRIT(701) instruc-
tion and the number of words/field.
The size is specified with the number of fields.
With word data, 1 word in I/O memory = 1 field
With long word data, 2 words in I/O memory = 1 field.
2. Data files do not contain information indicating what data is stored, i.e.,
what memory area is stored. Be sure to give file names that indicate the
contents, as shown in the examples below, to aid in file management.
Examples: D00100.IOM, CIO0020.IOM
Data from the beginning of the file will be written starting at the address
specified in I/O memory even if the data originally written to the data file
(IOM, TXT, or CSV) is not from the same area. For example, if CIO data in
a file is written to the DM Area from a Programming Device, the data will
be read to the DM Area of the CPU Unit without any indication that the area
is different.
Note Data files with the TXT and CSV format contain hexadecimal (0 to 9, A to F)
data that allows the I/O memory numerical data to be exchanged with spread-
sheet programs.
IOM Data File Structure The following illustration shows the binary data structure of a data file
(ABC.IOM) containing four words from I/O memory: 1234 Hex, 5678 Hex,
9ABC Hex, and DEF0 Hex. The user, however, does not have to consider the
data format in normal operations.
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