Automating Manufacturing Systems - Process Control and ...

plc iec61131 - 17.3
Name
Type
Bits
Range
BOOL
SINT
INT
DINT
LINT
USINT
UINT
UDINT
ULINT
REAL
LREAL
TIME
DATE
TIME_OF_DAY, TOD
DATE_AND_TIME, DT
STRING
BYTE
WORD
DWORD
LWORD
boolean
short integer
integer
double integer
long integer
unsigned short integer
unsigned integer
unsigned double integer
unsigned long integer
real numbers
long reals
duration
date
time
date and time
string
8 bits
16 bits
32 bits
64 bits
1
8
16
32
64
8
16
32
64
32
64
not fixed
not fixed
not fixed
not fixed
variable
8
16
32
64
0to1
-128 to 127
-32768 to 32767
-2.1e-9 to 2.1e9
-9.2e19to9.2e19
0 to 255
0 to 65536
0to4.3e9
0to1.8e20
not fixed
not fixed
not fixed
not fixed
variable
NA
NA
NA
NA
Figure 17.1
IEC 61131-3 Data Types
Previous chapters have described Ladder Logic (LD) programming in detail, and
Sequential Function Chart (SFC) programming briefly. Following chapters will discuss
Instruction List (IL), Structured Test (ST) and Function Block Diagram (FBD) programming
in greater detail.
17.3 OPEN ARCHITECTURE CONTROLLERS
Personal computers have been driving the open architecture revolution. A personal
computer is capable of replacing a PLC, given the right input and output components. As a
result there have been many companies developing products to do control using the personal
computer architecture. Most of these devices use two basic variations;
• a standard personal computer with a normal operating system, such as Windows
NT, runs a virtual PLC.