Omron Programmable Terminals NT631, Инструкции по эксплуатации

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520
Input of Numeric Values and Character Strings
Section 8-7
S
Using a thumbwheel type input field
At a thumbwheel type input field, input a numeric value using the increment/
decrement (+,
−
) keys provided at each digit position of the thumbwheel type
numeral setting field.
<Specifying a numeric value>
When an increment/decrement (+,
−
) key is pressed, the numeric value at the
corresponding digit increases or decreases by “1”. Each time the [+] key or the
[
−
] key is pressed, the changed numeric value is stored to the numeral memory
table and the occurrence of a change in the contents of the numeral memory
table is notified to the host. It is not necessary to confirm the input numeric value
by pressing the ENT key or the key, which is required when a numeric key type
input field is used.
With a thumbwheel type numeral setting input field, inputting of a numeric value
using the “input key – control” is not possible.
Numeral memory table
1 2 3 4
2 2 3 4
1
2 3 4
2 2 3 4
Setting a numeric value in the thumbwheel type input field.
Press
The relevant numeral increases by “1”.
Host
– – – –
– – – –
+ + + +
+ + + +
<Changing a sign>
If a check mark is set for “Display sign” of a thumbwheel type numeral setting
input field, the [+] and [
−
] keys are used to change the sign if the keys in the sign
display digit are pressed. Pressing the [+] key changes the sign to “+” and press-
ing the [
−
] key changes the sign to “
−
”.
<Checking the upper/lower limit>
The NT631/NT631C 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
y
m...m”, or pro-
vide a touch switch separately to write a numeric value for carry over or under-
flow.