Numbers, Codes, and Data Types for Siemens PLCs 220

base 10

The most commonly used number system in everyday life, also known as the decimal system. Each position in a base ten number represents a power of 10. The base 10 system uses ten digits, 0-9.

base 16

A commonly used numbering system for PLCs, also known as hexadecimal. Each position in a base 16 number represents a power of 16. Base 16 uses 16 characters: 0 through 9 and A through F.

base 2

The most commonly used number system in PLCs and other computer systems, also known as the binary system. Each position in a base 2 number represents a power of 2. The base 2 system has only 2 characters, 0 and 1.

base 8

A commonly used numbering system for PLCs, also known as octal. Each position in a base 8 number represents a power of 8. Base 8 only uses 8 characters, 0 through 7.

BCD

Binary-coded decimal. A binary-based code in which each decimal digit from 0 to 9 is represented by four binary bits.

binary

The most commonly used number system in PLCs and other computer systems, also known as the base 2. Each position in a binary number represents a power of 2. The binary system has only 2 characters, 0 and 1.

binary-coded decimal

BCD. A binary-based code in which each decimal digit from 0 to 9 is represented by four binary bits.

bit

Each position in a binary number. A bit may be a 0 or a 1.

bit strings

Consecutive groups of binary bits.

byte

A binary number made of 8 consecutive bits.

consecutive binary bits

Binary bits that fall after one another that may be used individually or as a group.

data type

A description of a bit string pattern in a PLC that shows how the PLC interprets the bit string.

decimal

A numbering system that uses ten digits, from 0 to 9, arranged in a series of columns to represent all numerical quantities. Each column or place value has a weighted value of 1, 10, 100, 1000, and so on, ranging from right to left.

DInt

Signed double integer. A type of integer used by a Siemens PLC that is 32 bits long. A signed double integer may have any decimal value between -2,147,483,648 to +2,147,483,647.

hexadecimal

A commonly used numbering system for PLCs, also known as base 16. Each position in a hexadecimal number represents a power of 16. Hexadecimal uses 16 characters: 0 through 9 and A through F.

Int

Signed integer. A type of integer used by a Siemens PLC that is 16 bits long. A signed integer may have any decimal value between -32,768 and +32,767.

integer

A positive or negative whole number.

least significant bit

LSB. In a binary number, the bit farthest to the right.

Lreal

Long real number. A type of real number that some SIMATIC PLCs can use that has 64 bits.

LSB

Least significant bit. In a binary number, the bit farthest to the right.

mantissa

The part of a floating-point number that represents the value that is multiplied by a power of ten.

most significant bit

MSB. In a binary number, the bit farthest to the left.

MSB

Most significant bit. In a binary number, the bit farthest to the left.

octal

A commonly used numbering system for PLCs, also known as base 8. Each position in an octal number represents a power of 8. Octal only uses 8 characters, 0 through 7.

power

A mathematical notation indicating the number of times a quantity is multiplied by itself. Also known as an exponent.

Real

A type of real number that a SIMATIC PLC can use that has 32 bits.

real numbers

A number that consists of a manitssa that is multiplied a power of 10 to arrive at the actual value.

scientific notation

A system of writing numbers that involves converting them to a mantissa multiplied by a power of ten.

signed

Indicates that a number can have a positive or negative sign.

signed double integer

DInt. A type of integer used by a Siemens PLC that is 32 bits long. A signed double integer may have any decimal value between -2,147,483,648 to +2,147,483,647

signed integer

Int. A type of integer used by a Siemens PLC that is 16 bits long. A signed integer may have any decimal value between -32,768 and +32,767.

signed short integer

SInt. A type of integer used by a Siemens PLC that is 8 bits long. A signed short integer may have any decimal value between -128 and +127.

SInt

Signed short integer. A type of integer used by a Siemens PLC that is 8 bits long. A signed short integer may have any decimal value between -128 and +127.

two’s complement

A system for writing negative numbers in binary in which the pattern of bits used to store a negative binary number is determined by inverting all the binary bits in the equivalent positive binary value and then adding a binary 1.

UDInt

Unsigned double integer. A type of integer used by a Siemens PLC that is 32 bits long. Unsigned double integers may have any decimal value between 0 and 4,294,967,295.

UInt

Unsigned integer. A type of integer used by a Siemens PLC that is 16 bits long. Unsigned integers may have any decimal value between 0 and 65,535.

unsigned

Indicates that a number can only represent 0 or positive numbers.

unsigned double integer

UDInt. A type of integer used by a Siemens PLC that is 32 bits long. Unsigned double integers may have any decimal value between 0 and 4,294,967,295.

unsigned integer

UInt. A type of integer used by a Siemens PLC that is 16 bits long. Unsigned integers may have any decimal value between 0 and 65,535.

unsigned short integer

USInt. A type of integer used by a Siemens PLC that is only 8 bits long. Unsigned short integers can have any decimal value between 0 and 255.

USInt

Unsigned short integer. A type of integer used by a Siemens PLC that is only 8 bits long. Unsigned short integers can have any decimal value between 0 and 255.