Start/stop
Start sets the output, Stop resets it with priority.
Open exampleBack to learning catalog
PLC and FBD
From training FBD diagrams to PLC logic
This track shows how conditions are used in a PLC: inputs are read at the scan boundary, blocks evaluate the program, states update, and outputs are written at the end of the scan.
What you learn
A PLC reads inputs, executes a program, and controls mechanism outputs.
FBD represents the program as a network of blocks: inputs, logic, memory, timers, counters, and outputs.
The scan cycle defines the order: input image, evaluation, state update, output image.
A training diagram simplifies an industrial project so the idea can be checked before a real controller.
Track topics
inputs and outputsPLC scan cycleFBD blocksinternal signalsRS / SRR_TRIG / F_TRIGTON / TOF / TPCTU / CTD / CTUDinterlockscommon automation diagrams
Practice
Practical PLC/FBD examples
These diagrams show start/stop, seal-in logic, delays, and counters in step-by-step simulation.
Seal-in logic
An RS latch shows how to retain state between scans.
Open exampleReverse interlock
Two mutually exclusive directions must not run at the same time.
Open exampleTON on-delay
The output turns on after a configured number of active scans.
Open exampleTOF off-delay
The output is held after command removal.
Open exampleCTU part counter
The counter reacts to pulses and turns on at the preset.
Open exampleSimple conveyor logic
Start, stop, permissives, and emergency blocking in one training diagram.
Open exampleRelated lessons
PLC and FBD lessons
01
What Is a PLC?
What a PLC does and how its inputs, program, and outputs work together.
Read lesson02
What Is FBD?
Read FBD diagrams: inputs, outputs, functional blocks, and their connections.
Read lesson03
Inputs, Outputs, and Internal Signals
How physical inputs and outputs differ from internal program signals.
Read lesson04
PLC Scan Cycle
How a PLC reads inputs, evaluates the program, updates state, and writes outputs.
Read lesson05
RS and SR Latches
Store Boolean state with Set/Reset latches and understand reset and set priority.
Read lesson06
TON On-Delay Timer
Understand on-delay timing and verify a timer over successive simulator scans.
Read lesson07
Two-Direction Interlock
Prevent two mutually exclusive movement commands from turning on together.
Read lesson08
Conveyor Logic
Conveyor control with start, stop, permissives, fault inhibits, and holding logic.
Read lesson09
90-Degree Box Pusher
A practical pneumatic pusher control diagram with a start delay and a limited push duration.
Read lesson