Siemens S7-200 PLC data length and value range - Database & Sql Blog Articles

Different data lengths can be used when addressing Siemens S7-200 plc. Different data lengths indicate different ranges of values. The S7-200 instructions also require different data lengths. The data types stored in the storage unit of the S7-200 series are Boolean (BOOL), integer (INT), real type and string type. The data length and value range are listed in Table 6. Table 1 data length and value range

Data type data length byte (8-bit value) word (16-bit value) double word (32-bit value) unsigned integer 0 to 255
0～FF0～65535
0～FFFF0～4294967295
0 to FFFF FFFF signed integer -128 to +127
80～7F-32768～+32767
8000～7FFF-217483648～+2147483647
8000 0000~7FFF FFFF real IEEE32-bit floating point number+1.175495E-38~+3.402823E+
38 (positive number)
-1.175495E-38～-3.402823E+38
(negative number) ● The real number of the real number (floating point number) is represented by a 32-bit single-precision number in the format described in the ANSI/IEEE 754-1985 standard. The real number is accessed in accordance with the length of the double word. For the S7-200, the floating point number is accurate to the sixth decimal place. Therefore, when using a floating-point constant, you can specify up to the sixth digit after the decimal point.
● The precision of real operations involves very large and very small numbers in the calculation, which may result in inaccurate calculation results.
● The format string of a string refers to a series of characters, each of which is stored in bytes. The first byte of the string defines the length of the string, which is the number of characters. A string can be from 0 to 254 characters long, plus a length byte. The maximum length of a string is 255 bytes. The maximum length of a string constant is 126 bytes.
● Boolean data (0 or 1).
● The S7-200 CPU does not support data type detection. For example, you can use the value in VW100 as a signed integer in the add instruction, and you can also treat the data in VW100 as an unsigned binary number in the XOR instruction.
● The S7-200 provides various conversion commands, which allows users to easily change the data format and expression.