Siemens S7-200 System Manual page 94

Using the Text Display Wizard to Configure the S7-200 CPU for Your Text Display (TD) Device
4.5 Configuring the Alarms
Data values are always right-justified to the right-most character of an embedded variable.
As a data value grows in magnitude, it utilizes more spaces to the left of the anchor point
and can overwrite the text characters. Always provide sufficient space between the end of
your text and the anchor point to allow for the expected range of the data value.
Tip
The actual number of characters used to display a value varies with the size of the value. To
help calculate the number of characters required for displaying the value of the variable, see
the examples listed in Table 4-2.
The TD device displays all values as decimal numbers. Positive signed values are displayed
without a sign, and negative signed values are displayed with a leading minus sign.
Unsigned values are displayed without a sign. A leading zero is used for all fractional
numbers (for example, 0.5). Real numbers are displayed with the number of decimal places
you specify. The value is rounded to the specified decimal place.
For more information about embedding string variables in an alarm, see page 53.
Table 4- 2
Size
Byte
(VB)
Word
(VW)
Double-Word
(VD)
The length of a line (number of characters in a line) varies by TD model and character size. The line
1
length is always 20 for a TD 200 or TD 200C. The line length is either 12 or 16 characters for a
TD 100C. The line length for the TD400C depends on the font you selected. If you selected a small
font, you have 24 ASCII characters or 12 Chinese characters per line. If you selected a large font,
you have 16 ASCII characters or 8 Chinese characters per line.
94
Calculating the Number of Characters Required to Display a Value
Type Resolution
(Digits to right
of decimal)
String Not applicable Line length
Numeric Not applicable Line length
String
Unsigned 0
1 to 4
5
6
7
Signed 0
1 to 4
5
6
7
Unsigned 0
1 to 7
Signed 0
1 to 7
Real 0
1 to 7
Maximum Number Example
of Characters
Hello, world
1
800.333.7421
1
5 12345
6 1234.5, 1.2345
7 0.12345
8 0.012345
9 0.0012345
6 -12345
7 -1234.5, -1.2345
8 -0.12345
9 -0.012345
10 -0.0012345
10 1234567890
11 123456789.1, 123.4567891
11 -1234567890
12 -123456789.1, -123.4567891
Line length -1234567
1
Line length 12345.6, 0.0123456
1
System Manual, 08/2008, A5E00765548-03
Text Display (TD) User Manual