INTRODUCTION TO FBD - Function Block Diagram by ( LOGO ) Revision 2.
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Transcript of INTRODUCTION TO FBD - Function Block Diagram by ( LOGO ) Revision 2.
INTRODUCTION TOINTRODUCTION TOFBD - Function Block Diagram byFBD - Function Block Diagram by
( LOGO )( LOGO )
Revision 2
Program Representation - FBDProgram Representation - FBDProgram Representation - FBDProgram Representation - FBD
» The graphical representation of a control task using symbols to DIN 40700 and DIN 19239
» Inputs are arranged on the left side while outputs on the right
FBD - Function Block Diagram
&I 0.0
I 0.1Q 4.0
FBDFBDFBDFBDOPERAND + OPERATION
OPERATION + OPERAND
= Q 4.0
Operation And OperandOperation And OperandOperation And OperandOperation And Operand
&I 0.0
M 80.0
Program ExecutionProgram ExecutionProgram ExecutionProgram Execution
PLC Scan Function:PLC Scan Function:
» Read the status of all inputs and outputs
» Examine the application program instructions
» Execute the control program
The Operand Areas :The Operand Areas :The Operand Areas :The Operand Areas :
» I (Input)Interface from the process to the programmable controller
» Q (Output)Interface from programmable controller to the process
» M (Memory/Flag)Memory for intermediate results of binary operations
Hardwire and PLC Wiring DiagramsHardwire and PLC Wiring DiagramsHardwire and PLC Wiring DiagramsHardwire and PLC Wiring Diagrams
How Does a Programmable Controller Work?How Does a Programmable Controller Work?How Does a Programmable Controller Work?How Does a Programmable Controller Work?
PowerSupply
ProgramMemory
ProcessorInput modules
Output modules
24 VDC
GND
Sensors
Actuators / Annunciators
Steps of Operation Steps of Operation Steps of Operation Steps of Operation
» The sensors are connected to the INPUT MODULES
» The processor in the CPU MODULE executes the program and scans the individual input for presence or absence of voltage
» Depending on the state of the inputs, the processor directs the OUTPUT MODULES to switch voltages
» The ACTUATORS or ANNUNCIATORS are switched “ON” or “OFF” according to the voltage states