Mission 23 · PRO

Build your first sequence chart: SFC PLC exercise

Ready. Fill. Complete.

Build a sequence that runs one fill: Ready, Fill, then Complete. Each phase is a step, a box in the chart, and only one step is active at a time. An action inside a step turns equipment ON while that step is active. A transition, the link to the next step, moves the chart on when its condition is .

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Every Coaching lesson, from zero
Every mission and lesson, as you level up
A practical test for every title, with a certificate
Rewind any test, one scan at a time
Worked solutions when you're stuck
The code converter, as much as you like

The 3D process tank this mission runs on

Level: Applied
Time: About 10 min
Reward: +250 XP
Rig: 3D process tank
Siemens editors: GRAPH
Rockwell editors: SFC
Stage: 12. One batch, clear phases

Required behaviour

Build your first sequence chart: what your code must do

Ready → Fill: PumpOn, FillValve, MixerOn, DrainValve and Done are all OFF. Start AND Permit moves to Fill.
Fill → Complete: PumpOn and FillValve ON. MixerOn, DrainValve and Done OFF. Level >= 70% moves to Complete.
Complete: Done ON. PumpOn, FillValve, MixerOn and DrainValve OFF. Done stays ON until the chart is reset.
Chart timing: In this simulator, a GRAPH or SFC chart runs a new step's actions one scan after it enters that step. So press Step scan twice to enter a phase and see its outputs.

Tag table

Build your first sequence chart: inputs and outputs

Your program reads 3 inputs and sets 5 outputs. The names are the same in every maker’s editor.

Tag	Data type	Your code	What it means on the machine
`Start`	`BOOL`	ReadsAn input your code needs	Start pushbutton
`Permit`	`BOOL`	ReadsAn input your code needs	Run permission: ON while it is safe to run
`Level`	`REAL`	ReadsAn input your code needs	Tank level, %
`PumpOn`	`BOOL`	WritesAn output your code sets	Fill pump
`FillValve`	`BOOL`	WritesAn output your code sets	Fill valve
`MixerOn`	`BOOL`	WritesAn output your code sets	Mixer command
`DrainValve`	`BOOL`	WritesAn output your code sets	Drain valve command
`Done`	`BOOL`	WritesAn output your code sets	Fill complete

Automatic tests

Build your first sequence chart: what the tests check

In Ready, PumpOn, FillValve, MixerOn, DrainValve and Done are all OFF. Start AND Permit moves to Fill.
Fill turns on PumpOn and FillValve. Level >= 70 moves to Complete, which turns Done ON.
Complete has no way out, so Done stays ON. MixerOn and DrainValve stay OFF in every step.
Only the listed for the current phase are ON. All the other equipment is OFF.

Try it Use the buttons below the model and watch the rig respond.
Test solution Every check runs on your code in one press.
Rewind PRO (needs Pro) If one fails, step back through it one scan at a time to see why.

Stuck on this mission? Ask the members in the Locker Room.

Why it matters

Where you’d see this on site

A drinks mixer is filled with ingredients before anything else happens. The fill must stop by itself when the tank is full.

A fill that never ends spills liquid onto the floor. A chart shows which step the job is in, so an engineer can see why it is waiting.

Where you'd find thisMaking one batch of drink

At a drinks factory, valves let measured amounts of water and syrup into a mixing tank. An electric mixer blends them into one batch. An outlet valve then sends the drink to a holding tank. Filling machines bottle it from there.

Ingredient tanksHold the water and syrup
Mixing tankFill, mix and measure one batchYou are here
Holding tankKeeps the finished drink ready
Bottle fillerPuts the drink into bottles

On a real site: places, parts and safety

Drinks factory — blending water and syrup
Paint factory — mixing ingredients into a consistent colour
Water-treatment works — preparing a measured chemical mixture
Brewery — heating water for washing equipment

A full tank does not close its own inlet. Water keeps arriving until the valve closes, so an open inlet can flood the room.

A heater that is not covered by liquid can overheat. Real tanks have separate safety devices as well as the PLC program.

The sizes, timings and cutaways are teaching choices, not a drawing of any one real installation.

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