Basic
10 min

Safety Mat Monitor

safetymatlatchingalarmreset
Safety Mat Monitor scenario preview

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Briefing

A safety mat system protects two hazardous zones. When a worker steps onto a mat (MAT_ZONE_1 or MAT_ZONE_2 goes true), the corresponding zone lamp latches on, HORN sounds, and MACHINE_STOP is asserted. The SILENCE_PB quiets the HORN without clearing the zone lamp. The RESET_PB clears the zone lamp and releases MACHINE_STOP — but only while the corresponding mat is unoccupied. Both mats can be tripped simultaneously.

Objectives

  • MAT_ZONE_1 pressed latches ZONE_1_LAMP and asserts MACHINE_STOP + HORN
  • MAT_ZONE_2 pressed latches ZONE_2_LAMP and asserts MACHINE_STOP + HORN
  • SILENCE_PB silences HORN but zone lamps remain on
  • RESET_PB clears zone lamp only when the corresponding mat is released
  • MACHINE_STOP de-energises only when both zone lamps are cleared
  • Both mats pressed simultaneously latches both zone lamps

Hints

  • Use separate latch bits (ZONE1_BIT, ZONE2_BIT): S= on mat press, R= on RESET_PB AND mat released
  • HORN: S= on any mat press, R= on SILENCE_PB OR when both lamps clear
  • MACHINE_STOP := ZONE1_BIT OR ZONE2_BIT
  • ZONE_1_LAMP := ZONE1_BIT; ZONE_2_LAMP := ZONE2_BIT
  • Mat inputs default FALSE (no one on mat). TRUE = person present.

I/O Table

Inputs

MAT_ZONE_1

Safety mat zone 1 (true = pressed)

BOOL · %I0.0

MAT_ZONE_2

Safety mat zone 2 (true = pressed)

BOOL · %I0.1

RESET_PB

Reset push-button (momentary)

BOOL · %I0.2

SILENCE_PB

Horn silence push-button (momentary)

BOOL · %I0.3

Outputs

ZONE_1_LAMP

Zone 1 fault indicator lamp

BOOL · %Q0.0

ZONE_2_LAMP

Zone 2 fault indicator lamp

BOOL · %Q0.1

HORN

Audible alarm horn

BOOL · %Q0.2

MACHINE_STOP

Machine stop relay (energised = stop)

BOOL · %Q0.3

Your program will be tested against:

All test cases run automatically when you submit. Assertions are hidden until you pass.

  1. #1MAT_ZONE_1 pressed latches ZONE_1_LAMP and asserts MACHINE_STOP

    Step on mat 1 — lamp latches, horn sounds, machine stops

  2. #2ZONE_1_LAMP stays latched after mat released (no reset)

    Mat released without reset — lamp must stay on, stop must stay asserted

  3. #3SILENCE_PB mutes HORN but zone lamp stays on

    Press SILENCE_PB — horn silences, zone lamp stays latched

  4. #4RESET_PB clears lamp only when mat is released

    Release mat then press RESET_PB — lamp clears and machine stop releases

  5. #5Both mats pressed latch both zone lamps independently

    Trip both mats; release mat 1 and reset clears only zone 1 lamp

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Runnable simulator field guide

Safety-mat monitoring scenario: implementation, evidence and troubleshooting

Direct answer

Safety-mat monitoring scenario becomes useful when it connects hazard, detection zone, clear state, occupied state, channel status, monitor fault, machine request, stopping state, reset permission and restart prevention with mat actuation through sensing channels and monitor state into safety request, final elements, modeled stopping response and reset feedback, then proves clear zone permitting a separate deliberate start, mat actuation removing hazardous request and release alone not restarting motion under normal, boundary, fault and recovery conditions. The objective is a repeatable engineering or learning result, not merely activity inside a page or tool.

This guide is written for automation learners studying how a pressure-sensitive protective device can be represented in a bounded machine-state model. The intended result is specific: the learner can distinguish clear, occupied, faulted and reset states, prevent hazardous command while occupied and test release without automatic restart.

a guarded machine-safety training cell with an emergency stop, two-hand station, safety mat, light curtain and inspectable relay panel while studying pressure-sensitive safety-mat state, channel monitoring, reset and hazardous-motion inhibition
This unbranded training scene makes the boundaries for pressure-sensitive safety-mat state, channel monitoring, reset and hazardous-motion inhibition visible so normal, abnormal and recovery evidence can be compared without implying target-equipment validation.

System map / 02

Six concepts that control the result

Treat these as connected checkpoints. Each checkpoint has an expected state, an observable state and a boundary to the next part of the system. That structure prevents a software indication from being mistaken for physical proof.

NODE 01observable

Define the operating contract

hazard, detection zone, clear state, occupied state, channel status, monitor fault, machine request, stopping state, reset permission and restart prevention. For pressure-sensitive safety-mat state, channel monitoring, reset and hazardous-motion inhibition, record the initial condition, actor, requested change, observable result and stopping condition before selecting a tool or implementation.

NODE 02observable

Map the evidence path

mat actuation through sensing channels and monitor state into safety request, final elements, modeled stopping response and reset feedback. Separate request, internal state, output or service, physical or user-visible result and independent feedback so each boundary can be inspected.

NODE 03observable

Prove normal operation

clear zone permitting a separate deliberate start, mat actuation removing hazardous request and release alone not restarting motion. Run more than one cycle from a known state and retain the values, timings or artifacts that demonstrate repeatability.

NODE 04observable

Exercise a boundary case

partial actuation, stuck state, open channel, short condition, reset held, person remains in zone, final-element fault, restart and power return. Choose minimum, maximum, simultaneous, delayed or restart conditions that reveal assumptions hidden by the happy path.

NODE 05observable

Diagnose a controlled fault

a mat, channel, monitor, request, final element, stopping, zone-clear, reset or restart mismatch. Preserve the first symptom, divide the system at a measurable boundary and change one condition only after predicting the result.

NODE 06observable

Transfer and hand over

the real application risk-assessed and validated using device response, stopping time, placement, environment and applicable standards. Restore normal state, remove temporary changes, repeat affected checks and document which claims remain limited to the learning environment.

Procedure / 03

A six-step practice and commissioning workflow

Run the steps in order the first time. Later, the same structure becomes a diagnostic loop: define the expected condition, observe the boundary, interpret the difference and choose one proving action.

  1. 01

    Write the acceptance case

    Convert hazard, detection zone, clear state, occupied state, channel status, monitor fault, machine request, stopping state, reset permission and restart prevention into initial conditions, one stimulus and observable pass criteria.

    Evidence: Another person can repeat the case without guessing the intended result.

    Avoid: Using page completion or an animation as the acceptance criterion.

  2. 02

    Build the map

    Document mat actuation through sensing channels and monitor state into safety request, final elements, modeled stopping response and reset feedback and name who owns each state or decision.

    Evidence: Every request and result has a source, destination and useful inspection point.

    Avoid: Using the same value as command, status and independent feedback.

  3. 03

    Run the baseline

    Apply clear zone permitting a separate deliberate start, mat actuation removing hazardous request and release alone not restarting motion from a clean start and record the expected evidence.

    Evidence: Repeated runs produce the same bounded result.

    Avoid: Changing several parameters before a baseline exists.

  4. 04

    Challenge assumptions

    Test partial actuation, stuck state, open channel, short condition, reset held, person remains in zone, final-element fault, restart and power return without changing the acceptance contract.

    Evidence: Limits, timing and restart behavior reach defined states.

    Avoid: Testing only one ideal sequence.

  5. 05

    Isolate one failure

    Introduce or analyse a mat, channel, monitor, request, final element, stopping, zone-clear, reset or restart mismatch and locate the first disagreement.

    Evidence: The proving action distinguishes the leading hypotheses.

    Avoid: Resetting, forcing or replacing before evidence is retained.

  6. 06

    Close the evidence loop

    Complete the real application risk-assessed and validated using device response, stopping time, placement, environment and applicable standards and repeat the affected regression cases.

    Evidence: A run is complete only when the requested behavior, stop behavior, fault response and recovery are observable from a fresh initial condition.

    Avoid: Treating an acknowledged message or one successful rerun as handover.

Diagnostic matrix / 04

Symptoms, proving points and next actions

The table is a reasoning aid, not a parts-replacement chart. Preserve the initial symptom, inspect the named boundary and use the interpretation to choose the next controlled test. Site safety procedures and equipment manuals remain authoritative.

Diagnostic symptoms, inspection points, interpretations and next actions for Safety-mat monitoring scenario: implementation, evidence and troubleshooting
Observed symptomInspectInterpretationNext proving action
The expected result is unclearRequirement, initial state, actor, stimulus, units and pass conditionThe operator, programmer and reviewer may be solving different versions of the task.Rewrite one observable acceptance case before continuing.
Internal state changes but the outcome does notRequest, final owner, output or service boundary and independent feedbackA software or interface indication proves intent at one layer, not the complete outcome.Trace the first boundary after the changing state.
Normal case passes but an edge case failsLimits, timing, simultaneous events, reset and restart assumptionsThe implementation contains a hidden assumption exposed by the changed condition.Add the failed boundary as a permanent regression case.
The failure disappears after resetOriginal symptom, histories, diagnostics, timestamps and active causeReset changed evidence or state without proving the initiating cause.Reproduce under a controlled condition and preserve pre/post-event data.
Simulator and target disagreeModel boundary, software version, task timing, I/O behavior, data types and configurationA learning model and the intended target do not share one of the recorded assumptions.Reduce the case and verify against current target documentation.
The result cannot be explainedPrediction, observation, proving action, alternative hypotheses and limitationsActivity occurred but the evidence is not yet transferable or reviewable.Have the learner defend the signal path and repeat a changed case.

Product evidence / 05

What the browser practice can actually demonstrate

The browser runtime joins editable control state to visible I/O and machine or process behavior, allowing the same initial conditions and stimuli to be replayed.

Where simulation stops

The model does not select, install or validate a safety mat, determine safe distance or response time, or assign a safety performance level.

Commissioning notebook / 06

Six cases that turn the concepts into evidence

Use these as written briefs rather than click-through instructions. For every case, state the expected condition before acting, retain the first useful observation and explain why the final result proves the requirement. A different program or component choice can still be correct when it produces the same bounded behavior and evidence.

Case 01

predict → observe → prove

Prove define the operating contract

Engineering context. hazard, detection zone, clear state, occupied state, channel status, monitor fault, machine request, stopping state, reset permission and restart prevention. For pressure-sensitive safety-mat state, channel monitoring, reset and hazardous-motion inhibition, record the initial condition, actor, requested change, observable result and stopping condition before selecting a tool or implementation. Begin with a written normal condition and identify which request, state, physical result or communication value will provide independent confirmation. Do not begin by changing the configuration; the initial state is part of the evidence and should remain reproducible.

Controlled setup. Use the “Write the acceptance case” stage of the workflow: convert hazard, detection zone, clear state, occupied state, channel status, monitor fault, machine request, stopping state, reset permission and restart prevention into initial conditions, one stimulus and observable pass criteria. The acceptance record should show this result: another person can repeat the case without guessing the intended result. Record initial conditions, the exact stimulus and the observation point so another learner can repeat the case without relying on your memory.

Fault challenge. Introduce or analyse “The expected result is unclear” as one bounded deviation. Inspect requirement, initial state, actor, stimulus, units and pass condition The working interpretation is that the operator, programmer and reviewer may be solving different versions of the task. The next proving action is to rewrite one observable acceptance case before continuing. Change only one condition before observing the result, and preserve timestamps or measurements where timing matters.

Review and recovery. The most common trap here is using page completion or an animation as the acceptance criterion. After restoring the cause, repeat the normal case and at least one stop, timeout, disconnect or restart boundary relevant to this topic. Remove temporary forces and bypasses, return the model to a known state and retain the evidence that both operation and recovery are deliberate.

Explain it aloud: What should happen when a safety mat is stepped on? A defensible short answer is: The protective function should request the defined stop or inhibit hazardous motion; the exact response depends on the risk assessment and validated safety architecture.

Case 02

predict → observe → prove

Prove map the evidence path

Engineering context. mat actuation through sensing channels and monitor state into safety request, final elements, modeled stopping response and reset feedback. Separate request, internal state, output or service, physical or user-visible result and independent feedback so each boundary can be inspected. Begin with a written normal condition and identify which request, state, physical result or communication value will provide independent confirmation. Do not begin by changing the configuration; the initial state is part of the evidence and should remain reproducible.

Controlled setup. Use the “Build the map” stage of the workflow: document mat actuation through sensing channels and monitor state into safety request, final elements, modeled stopping response and reset feedback and name who owns each state or decision. The acceptance record should show this result: every request and result has a source, destination and useful inspection point. Record initial conditions, the exact stimulus and the observation point so another learner can repeat the case without relying on your memory.

Fault challenge. Introduce or analyse “Internal state changes but the outcome does not” as one bounded deviation. Inspect request, final owner, output or service boundary and independent feedback The working interpretation is that a software or interface indication proves intent at one layer, not the complete outcome. The next proving action is to trace the first boundary after the changing state. Change only one condition before observing the result, and preserve timestamps or measurements where timing matters.

Review and recovery. The most common trap here is using the same value as command, status and independent feedback. After restoring the cause, repeat the normal case and at least one stop, timeout, disconnect or restart boundary relevant to this topic. Remove temporary forces and bypasses, return the model to a known state and retain the evidence that both operation and recovery are deliberate.

Explain it aloud: Should a machine restart when someone steps off a safety mat? A defensible short answer is: No automatic restart should result merely from clearing the mat. A separate controlled reset and deliberate start should follow the approved design.

Case 03

predict → observe → prove

Prove prove normal operation

Engineering context. clear zone permitting a separate deliberate start, mat actuation removing hazardous request and release alone not restarting motion. Run more than one cycle from a known state and retain the values, timings or artifacts that demonstrate repeatability. Begin with a written normal condition and identify which request, state, physical result or communication value will provide independent confirmation. Do not begin by changing the configuration; the initial state is part of the evidence and should remain reproducible.

Controlled setup. Use the “Run the baseline” stage of the workflow: apply clear zone permitting a separate deliberate start, mat actuation removing hazardous request and release alone not restarting motion from a clean start and record the expected evidence. The acceptance record should show this result: repeated runs produce the same bounded result. Record initial conditions, the exact stimulus and the observation point so another learner can repeat the case without relying on your memory.

Fault challenge. Introduce or analyse “Normal case passes but an edge case fails” as one bounded deviation. Inspect limits, timing, simultaneous events, reset and restart assumptions The working interpretation is that the implementation contains a hidden assumption exposed by the changed condition. The next proving action is to add the failed boundary as a permanent regression case. Change only one condition before observing the result, and preserve timestamps or measurements where timing matters.

Review and recovery. The most common trap here is changing several parameters before a baseline exists. After restoring the cause, repeat the normal case and at least one stop, timeout, disconnect or restart boundary relevant to this topic. Remove temporary forces and bypasses, return the model to a known state and retain the evidence that both operation and recovery are deliberate.

Explain it aloud: What should I learn first about pressure-sensitive safety-mat state, channel monitoring, reset and hazardous-motion inhibition? A defensible short answer is: Start with the operating contract and evidence path: hazard, detection zone, clear state, occupied state, channel status, monitor fault, machine request, stopping state, reset permission and restart prevention, followed by mat actuation through sensing channels and monitor state into safety request, final elements, modeled stopping response and reset feedback. Add advanced features only after the baseline is predictable.

Case 04

predict → observe → prove

Prove exercise a boundary case

Engineering context. partial actuation, stuck state, open channel, short condition, reset held, person remains in zone, final-element fault, restart and power return. Choose minimum, maximum, simultaneous, delayed or restart conditions that reveal assumptions hidden by the happy path. Begin with a written normal condition and identify which request, state, physical result or communication value will provide independent confirmation. Do not begin by changing the configuration; the initial state is part of the evidence and should remain reproducible.

Controlled setup. Use the “Challenge assumptions” stage of the workflow: test partial actuation, stuck state, open channel, short condition, reset held, person remains in zone, final-element fault, restart and power return without changing the acceptance contract. The acceptance record should show this result: limits, timing and restart behavior reach defined states. Record initial conditions, the exact stimulus and the observation point so another learner can repeat the case without relying on your memory.

Fault challenge. Introduce or analyse “The failure disappears after reset” as one bounded deviation. Inspect original symptom, histories, diagnostics, timestamps and active cause The working interpretation is that reset changed evidence or state without proving the initiating cause. The next proving action is to reproduce under a controlled condition and preserve pre/post-event data. Change only one condition before observing the result, and preserve timestamps or measurements where timing matters.

Review and recovery. The most common trap here is testing only one ideal sequence. After restoring the cause, repeat the normal case and at least one stop, timeout, disconnect or restart boundary relevant to this topic. Remove temporary forces and bypasses, return the model to a known state and retain the evidence that both operation and recovery are deliberate.

Explain it aloud: How do I practise pressure-sensitive safety-mat state, channel monitoring, reset and hazardous-motion inhibition effectively? A defensible short answer is: Use short cases with known initial conditions, a written prediction, one action and an observable result. Then alter a boundary or fault and explain why the evidence changed.

Case 05

predict → observe → prove

Prove diagnose a controlled fault

Engineering context. a mat, channel, monitor, request, final element, stopping, zone-clear, reset or restart mismatch. Preserve the first symptom, divide the system at a measurable boundary and change one condition only after predicting the result. Begin with a written normal condition and identify which request, state, physical result or communication value will provide independent confirmation. Do not begin by changing the configuration; the initial state is part of the evidence and should remain reproducible.

Controlled setup. Use the “Isolate one failure” stage of the workflow: introduce or analyse a mat, channel, monitor, request, final element, stopping, zone-clear, reset or restart mismatch and locate the first disagreement. The acceptance record should show this result: the proving action distinguishes the leading hypotheses. Record initial conditions, the exact stimulus and the observation point so another learner can repeat the case without relying on your memory.

Fault challenge. Introduce or analyse “Simulator and target disagree” as one bounded deviation. Inspect model boundary, software version, task timing, I/O behavior, data types and configuration The working interpretation is that a learning model and the intended target do not share one of the recorded assumptions. The next proving action is to reduce the case and verify against current target documentation. Change only one condition before observing the result, and preserve timestamps or measurements where timing matters.

Review and recovery. The most common trap here is resetting, forcing or replacing before evidence is retained. After restoring the cause, repeat the normal case and at least one stop, timeout, disconnect or restart boundary relevant to this topic. Remove temporary forces and bypasses, return the model to a known state and retain the evidence that both operation and recovery are deliberate.

Explain it aloud: What counts as proof of competence? A defensible short answer is: A repeatable artifact or system result plus an explanation of the signal path is stronger than time spent, screenshots or a copied answer. Physical competence requires separate supervised evidence.

Case 06

predict → observe → prove

Prove transfer and hand over

Engineering context. the real application risk-assessed and validated using device response, stopping time, placement, environment and applicable standards. Restore normal state, remove temporary changes, repeat affected checks and document which claims remain limited to the learning environment. Begin with a written normal condition and identify which request, state, physical result or communication value will provide independent confirmation. Do not begin by changing the configuration; the initial state is part of the evidence and should remain reproducible.

Controlled setup. Use the “Close the evidence loop” stage of the workflow: complete the real application risk-assessed and validated using device response, stopping time, placement, environment and applicable standards and repeat the affected regression cases. The acceptance record should show this result: a run is complete only when the requested behavior, stop behavior, fault response and recovery are observable from a fresh initial condition. Record initial conditions, the exact stimulus and the observation point so another learner can repeat the case without relying on your memory.

Fault challenge. Introduce or analyse “The result cannot be explained” as one bounded deviation. Inspect prediction, observation, proving action, alternative hypotheses and limitations The working interpretation is that activity occurred but the evidence is not yet transferable or reviewable. The next proving action is to have the learner defend the signal path and repeat a changed case. Change only one condition before observing the result, and preserve timestamps or measurements where timing matters.

Review and recovery. The most common trap here is treating an acknowledged message or one successful rerun as handover. After restoring the cause, repeat the normal case and at least one stop, timeout, disconnect or restart boundary relevant to this topic. Remove temporary forces and bypasses, return the model to a known state and retain the evidence that both operation and recovery are deliberate.

Explain it aloud: Why test faults and restart behavior? A defensible short answer is: Because a mat, channel, monitor, request, final element, stopping, zone-clear, reset or restart mismatch or partial actuation, stuck state, open channel, short condition, reset held, person remains in zone, final-element fault, restart and power return can expose assumptions that never appear during ideal startup and steady operation.

Answer surface / 07

Questions people ask about Safety-mat monitoring scenario

These concise answers define the operating, training and product boundaries most often missed in broad summaries. The full workflow and diagnostic table above provide the evidence behind them.

What should happen when a safety mat is stepped on?

The protective function should request the defined stop or inhibit hazardous motion; the exact response depends on the risk assessment and validated safety architecture.

Should a machine restart when someone steps off a safety mat?

No automatic restart should result merely from clearing the mat. A separate controlled reset and deliberate start should follow the approved design.

What should I learn first about pressure-sensitive safety-mat state, channel monitoring, reset and hazardous-motion inhibition?

Start with the operating contract and evidence path: hazard, detection zone, clear state, occupied state, channel status, monitor fault, machine request, stopping state, reset permission and restart prevention, followed by mat actuation through sensing channels and monitor state into safety request, final elements, modeled stopping response and reset feedback. Add advanced features only after the baseline is predictable.

How do I practise pressure-sensitive safety-mat state, channel monitoring, reset and hazardous-motion inhibition effectively?

Use short cases with known initial conditions, a written prediction, one action and an observable result. Then alter a boundary or fault and explain why the evidence changed.

What counts as proof of competence?

A repeatable artifact or system result plus an explanation of the signal path is stronger than time spent, screenshots or a copied answer. Physical competence requires separate supervised evidence.

Why test faults and restart behavior?

Because a mat, channel, monitor, request, final element, stopping, zone-clear, reset or restart mismatch or partial actuation, stuck state, open channel, short condition, reset held, person remains in zone, final-element fault, restart and power return can expose assumptions that never appear during ideal startup and steady operation.

Can browser practice replace official software or hardware?

No. It can build concepts and diagnostic reasoning. Exact firmware, I/O electrical behavior, networking, safety and commissioning require current official tools, documentation and target equipment.

How should progress be documented?

Keep the requirement, initial state, program or configuration, observed values, fault hypothesis, proving action, recovery result and a concise limitations statement.