Siemens S7-200 System Manual page 85

Using the Text Display Wizard to Configure the S7-200 CPU for Your Text Display (TD) Device
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 4-1.
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.
Table 4- 1
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.
Embedded String Variables
There are special considerations when you set up a string variable for the TD devices. String
variables are positioned the same as numeric variables, that is, the right-most character of
the variable is positioned at the right-most position of the embedded variable in the Text
Display wizard. This can cause problems when you want to place a text string adjacent to
other text in the message.
Text Display (TD) User Manual
System Manual, 08/2008, A5E00765548-03
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
4.4 Configuring the Screens for the Text Display Device
Maximum Number
of Characters
1
1
5
6
7
8
9
6
7
8
9
10
10
11
11
12
Line length
1
Line length
1
Example
Hello, world
800.333.7421
12345
1234.5, 1.2345
0.12345
0.012345
0.0012345
-12345
-1234.5, -1.2345
-0.12345
-0.012345
-0.0012345
1234567890
123456789.1, 123.4567891
-1234567890
-123456789.1, -123.4567891
-1234567
12345.6, 0.0123456
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