Siemens Simatic S7-200 System Manual page 63

Warning
!
STEP 7-Micro/WIN uses column 1 of every line in the Data Block Editor to determine the
starting address for the values to be stored in the data block. If you enter a number in
column 1, that number is interpreted as the starting address in V memory for any data that
follow. If you intended the number in column 1 to be a data value and not an address, this
could inadvertently cause data entered in the data block to be overwritten by the new data.
Referencing incorrect data could lead to unpredictable activity within the process when you
download the data block to a CPU. Unpredictable operations could cause death or serious
personal injury and/or damage to equipment.
To help ensure that data are stored in the correct locations in V memory, always specify a
size and address, such as VB100. Also, always proofread carefully to ensure that no data
value was inadvertently entered in column 1.
Table 3-4 gives examples of the notation to be used when entering values for a data block.
Table 3-4 Notation for Entering Values in a Data Block
Hexadecimal
Integer (decimal)
Signed integer (decimal)
Real (floating point): use a period (".") and not a comma (",")
Text (ASCII): string text, contained within apostrophes
(Note: "$" is a special character for designating that the following character is an
apostrophe or a dollar sign within a string.)
Table 3-5 shows the valid designators for entering the data size and starting address.
Table 3-5 Valid Size Designators
Size of Data
Byte
Word
Double Word
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S7-200 Programmable Controller System Manual
C79000-G7076-C230-02
Installing and Using the STEP 7-Micro/WIN Software
Data Type
Example
VB10 Stores the values that follow as bytes of data, starting at the
address specified.
VW22 Stores the values that follow as words of data, starting at the
address specified.
VD100 Stores the values that follow as double words of data, starting
at the address specified.
V10 Stores the data in the minimum size (byte, word, or double
word) required for storing the values. The values entered on
that line are stored starting at the specified V address.
(Address column Stores data in byte, word, or double word, depending on the
is empty) size specified in the preceding line.
Example
16#AB
10 or
-10 or
10.57
'Siemens'
'That$'s it'
'Only $$25'
Description
20
+50
3-33