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2-3
Section
Memory Tables
67
instead to denote negative values (a negative sign can be used in the setting
for Value. so negative values can be input in the normal manner for this set-
ting).
If a value with a letter from A to E inclusive as its most significant digit, or a
value with a letter from A to F inclusive at any position other than the most
significant digit is stored in a host word, it is invalidated as illegal data and the
existing value is retained.
If the contents of a numeral memory table exceed the range that can be han-
dled by the allocated words of the host, the value is written to the host as
negative sign + less significant digits (see below).
Contents of numeral memory
table (decimal notation)
Data at
host
Conditions
12345
→
2345
1 allocated word
–12345
→
F345
1 allocated word
When using BCD format
123456789
→
23456789
2 allocated words
–12345678
→
F2345678
2 allocated words
When using BCD format
•
Storage Type For Binary Format
When binary format is used, the initial value and contents of the host word(s)
are interpreted as signed binary data and are stored without change in the nu-
meral memory table.
With binary format, the most significant bit is the sign bit (when this bit is 1 it
indicates a negative value). When there is one allocated word, the most sig-
nificant bit is bit 15; when there are two allocated words it is bit 31.
The initial value is always expressed as a 2-word signed binary value re-
gardless of the Storage Type setting.
However, when the initial value is input using the Support Tool, the basis for
input is always the decimal system. The – symbol can be input to indicate a
negative value. If $ is input at the head of the input value, it will be input as a
hexadecimal value (after confirmation of input, it is displayed in decimal).
Data Flow and Stored Data
The table below indicates how the set Value (initial value) and the contents of
host words are stored in numeral memory tables. (The examples show initial val-
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Summary of Contents for NT21 Series
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