Omron NT21 Reference Manual page 221

Inputting Numeric Values
Reference: Numeral memory table entries store numeric values as signed binary data.
When the word allocated in the host is input to a 1-word memory table entry, the
input value is treated as 4-digit (16-bit) signed binary data so it is converted to
8-digit signed binary data before being stored.
For example, if a value of 8001 hexadecimal is input to a 1-word numeral
memory table entry, it is recognized as a negative value because the most sig-
nificant bit is ON. The value actually stored in the numeral memory table entry
is FFFF 8001 hexadecimal.
Permissible Input Range
When inputting values into numeral memory table entries, the permissible input
range is affected not just by the Display Type and Display Sign but also the Stor-
age Type and Words settings. (When words are not allocated for the numeral
memory table entry in the host, the Words setting is treated as 2 words.)
The permissible input range is determined as shown below depending on these
properties. If input of a value outside this range is attempted, the PT checks and
prevents the input.
Storage Display
Words
Type Type
Decimal Decimal
1 1
Hexadecimal
BCD
Decimal Decimal
2 2
Hexadecimal
Decimal Decimal
1
Hexadecimal
Binary Binary
Decimal Decimal
2
Hexadecimal
* Note that the values are different from those of the numeral display range. In
numeral display, since negative numbers are displayed as absolute values when
displaying unsigned decimal values, 32768 and 2147483648, which cannot be
input, may be displayed.
Relationship Between Input Numeric Values and Contents of Host Words
When inputting a numeric value to a numeral memory table entry for which a
word is allocated in the host, the value is first converted to signed binary in accor-
dance with the settings for Display Type and Display Sign settings and stored in
the numeral memory table, and then written to the host word in accordance with
the Words and Storage Type settings for the numeral memory table entry.
Sign Permissible Input Range
Unsigned 0 to 9999
Signed –999 to 9999
FC19 to FFFF
H
–
0 to 270F (positive numbers)
H
Unsigned 0 to 99999999
Signed –9999999 to 99999999
FF676981 to FFFFFFFF
– (negative numbers)
0 to 5F5E0FF
Unsigned 0 to 32767
Signed –32768 to 32767
– 0 to FFFF
Unsigned 0 to 2147483647
Signed –2147483648 to 2147483647
– 0 to FFFFFFFF
Section 2-12
(negative numbers)
H
(positive numbers)
H
*
H
*
H
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