PLCTrain learning guide / Simulation examples
Run command: ON.
Conveyor: STOPPED.
Both can be true.
A request to run is not evidence that a motor or belt is moving. Keeping the request, the program's output, and the machine's response separate makes troubleshooting much easier.
Run command: ON means operation has been requested. RUNNING or STOPPED describes the modeled belt motion. Other conditions can still prevent motion after a request.
Keep these four statements separate
- The controller is in RUN mode.
- The controller is executing its configured program. This does not mean every conveyor output is on.
- A run command is ON.
- A control request exists. The program may still require other conditions to be satisfied.
- The output command is ON.
- The logic is requesting that output. On real equipment, this is not proof that the drive, motor, or belt actually responded.
- The conveyor is RUNNING.
- Motion is occurring in the simulation. On a real installation, actual motion must be established through its designed feedback and authorized observation, not assumed from an output bit.
A simple receiving-zone example
Imagine a run-permission rule that requires a run command and a clear receiving zone. This table explains that one rule only; it is not the complete machine program or a safety circuit.
| Run command | Receiving zone | Run permission | Why? |
|---|---|---|---|
| OFF | Clear | OFF | No run request. |
| OFF | Occupied | OFF | No run request. |
| ON | Clear | ON | Both conditions are satisfied. |
| ON | Occupied | OFF | The receiving zone cannot accept another box. |
Explain the stopped state before changing anything
When a run request is on but the belt is stopped, first ask whether the program is allowing that belt to run. In Conveyor Rescue, compare the requested state, receiving photoeye, named PLC tag, rung condition, and simulated belt output.
If the rung is deliberately refusing a start because a required condition is false, that is a different problem from a commanded motor failing to move. On real equipment, an output being on can coexist with a drive fault, missing power, or a mechanical problem. Those require the equipment's specific diagnostic and safety procedures; this browser demo does not reproduce every failure.
Why the training questions say RUNNING or STOPPED
The questions ask you to predict behavior, not press a hidden start button. Read the two stated conditions, choose the expected result, then compare your answer with the check. A wrong prediction is useful feedback, not something to hide by changing it before you understand it.
Run command is ON and the receiving zone is occupied. Is STOPPED a fault?
Not for the simple rule above. Stopping is the intended response. The fault is when the actual evidence and the reported condition disagree, or the control rule allows the wrong behavior.
What a maintenance manager can ask
Instead of asking only, "Did you get it running?", ask: "What prevented the output? What observation supported that? Which test would show it stops when it should?" These questions reveal whether the learner can reason through the conditions or is just clicking until something moves.
Read the source, too.
The examples above describe PLCTrain. These manufacturer references explain the underlying concepts; they are not endorsements of PLCTrain.