6.5.18 String to real number
Input/output Operand
Data type
IN
VB,constant string, LB, *VD, *LD, *AC
String
INDX
VB, IB, QB, MB, SB, SMB, LB,Constant, AC,*VD, *LD, *AC Byte
OUT
VD, ID, QD, MD, SD, SMD, LD, AC, *VD, *LD, *AC
Real number
S - R:The instruction converts the string value “ IN ” to the real number value stored in the “ OUT ” , starting with
the offset INDX location.
ASCII constant string data type format ：
String is a series of characters, each character is stored as a byte.The first byte of a
string defines the length of the string, that is the number of characters.If a constant
string is entered directly into the program editor or data block, the string must start
and end with double quotation marks ("string constant").
The following memory map shows the format of the string data type.The length of a
string can be between 0 and 254 characters.The maximum length of the string is 255
bytes. String length
Character 1
Character 2
Character 5
Character 254
Character
Character
..................................
3
4
Byte 0
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Byte 254
INDX value is typically set to 1,starting conversion from the first character of the
string.INDX value can be set to other values.This method can be used when the input
string contains characters that are not required to be converted.For example, if the
input string is “ Temperature: 77.8 ” ,you can set INDX value 13 to skip the
characters "Temperature:".
When the end of the string is reached or when the first invalid character
is found, the conversion is terminated.Invalid character is any character
other than number (0-9).
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