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Basics of PLC Programming - Coggle Diagram
Basics of PLC Programming
Processor Memory Organization
System Functions
file 0
contains various system related information
Reserved
file 1
reserved by the processor, is not accessible by user
Main Ladder Program
file 2
contains user pre-programmed instructions
Subroutine ladder program
files 3-255
user created and activated according to subroutine instructions
Processor Memory Organization pt.2
Data files
Counter
file 5
stores the counter accumulated and preset values and status bits
Control
file 6
stores length, pointer, position, and status bit for specific instructions
Timer
file 4
stores the timer accumulated and preset values and status bits
Integer
file 7
stores numerical values or bit information
Bit
file 3
internal relay logic storage
Reserved
file 8
Not accessible by user
Status
file 2
stores controller operation information
Network Communications
file 9
used for network communications
input
file 1
stores the status of the input terminals
User-defined
files 10-255
user-defined as bit, timer, counter, control, and integer data storage
Output
file 0
stores the state of the output terminals
PLC Programming Languages
Sequential Function Chart
SFC
depicts interconnecting steps, actions, and transitions
Instruction List
IL
uses mnemonic instructions
Function Block Diagram
FBD
depiction of the flow of the process
Structured text
ST
BASIC, C, or PASCAL languages
Ladder Diagram
LD
graphical depiction of a process with rungs of logic
Modes of Operation
Run Mode
executes the users program
Test Mode
Used to test the user program without actually energizing any logic
Program Mode
allows for new programs to be uploaded
Remote Mode
allows for remote operation of PLC