Omron NT31 Operation Manuals page 442

Inputting Numeric Values
Notice
[Display Functions]
[Input Functions]
[Output Functions]
[Processing Functions]
S Upper/lower (max./min.) limit check
The NT31/NT31C has a function to check the correctness of an input numeric
value to prevent a numeric value outside the allowable range from being input so
that the input of an illegal value will not adversely affect the system.
The upper/lower (max./min.) limit check is executed in the timing indicated be-
low according to the type of a numeral setting input field.
For a thumbwheel type numeral setting input field, the check is executed each
time the increment/decrement key of each digit position is pressed.
With a thumbwheel type numeral setting input field, if n...n < m...m [upper limit:
1n...n, lower limit: 0m...m ("n" and "m" are arbitrary values at each digit)], carry
over and underflow are not possible at the highest digit position.
Example:
If the upper limit value and the lower limit value are 1200 and 201, respectively,
the numeric value can be changed only in the following range: from 201 to 999 if
an initial value is a 3-digit value and from 1000 to 1200 if an initial value is a 4-digit
value.
The reason for this is that the upper/lower (max./min.) limit check function does
not allow the numeric value at the highest digit position to change from 0 to 1 or
from 1 to 0.
To avoid this, set the upper and lower limit values so that "n...n ≧ m...m", or pro-
vide a touch switch separately to write a numeric value for carry over or under-
flow.
When the numeral values entered are confirmed, upper/lower limits are checked.
Numeric values are displayed in the numeral setting input field in accordance with
the "General" settings.
For details on the method of display according to the "General" settings, refer to
"Common Attributes" (page 426).
Numeric values are input into a thumbwheel type numeral setting input field by us-
ing the "+" and "$" touch switches provided for each digit.
Numeral setting input fields only write input numeric values to numeral memory
tables; they have no function for directly outputting data to external destinations (if
the numeral memory table to which the numeric value is written is allocated to the
host, the value table can be output to the host indirectly).
However, the input of a numeric value is notified to the host via the PT status notify
area.
Numeral setting input fields have no data processing functions.
Section 7-12
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