Siemens SIMATIC TD 200 User Manual page 115

The TD 200 displays all values as decimal numbers. Various types of data are
displayed in the following manner:
Positive signed values are displayed without a sign.
Negative signed values are displayed with a leading minus sign.
Unsigned values are displayed without a sign.
Values without non-zero digits to the left of the decimal point are displayed with
a leading zero on the left side of the decimal point.
Real (floating point) numbers are displayed with the number of decimal places
that you specified (see Figure D-18). The value is rounded to the designated
level of precision. For example, if one decimal place were specified for the
value 12.567, the TD 200 would display "12.6".
The number of display characters that are used to display a value varies. This
variation is not reflected in the number of bytes that are required to store the value
in the S7-200 CPU memory. In the CPU memory, two bytes are required to store a
word value, and four bytes are required to store a double word or a real (floating
point) value.
Table D-2 shows you how many display characters are required for each display
format and the maximum number of display characters required for each format.
For example, if you know that the size of the value will never exceed three digits
and will always be positive, then the number of display characters required will
always be less than the maximum values given in Table D-2.
For real (floating point) numbers, the TD 200 uses up to 20 digits to represent the
number. (This includes the number of decimal places that were specified in the
format word. See Figure D-18.) If a number cannot be displayed within the number
of digits available, the TD 200 displays "eeeeee" for that value.
SIMATIC TD 200 Operator Interface
C79000-G7076-C272-01
TD 200 Parameters and Messages
D-19