Scheme of work

Teaching PLC Academy

Six sessions of roughly two hours. Adjust freely — the levels are the fixed thing, everything else here is a suggestion. Take it, cut it, ignore it.

Learning outcomes by chapter

Chapter	Levels	Outcomes
1 · Relay panel to rung	1–8	Contacts and coils; series/parallel as AND/OR; NO vs NC; latching with Set/Reset; the seal-in (DOL starter); fail-safe wiring and why stop circuits are normally closed; hand/off/auto mode selection
2 · Time and count	9–14	On-delay and off-delay timers; building an oscillator from feedback; rising and falling edges and the one-shot; up counters; star-delta changeover with mutual interlocking
3 · Real machines	15–18	Step sequencers; reversing drives with limits and interlocks; hysteresis and deadband; two-hand anti tie-down control
4 · FBD	19–21	Function Block Diagram; AND/OR/NOT; SR vs RS latches and reset dominance; where an interlock belongs
5 · SCL	22–25	Structured Text: assignment, IF/ELSIF, function-block instance calls, CASE state machines
6 · STL	26–28	Statement List: the RLO, first check, AND-before-OR, nesting, S7 timers
7 · The Gauntlet	29–38	Ten applied jobs: bidirectional counting, first-out annunciation, batch sequencing, part tracking, duty/standby with failover, ramp and soak, limit-confirmed sequencing, fault handling with codes, cascade start/stop, a full specification
8 · Certification	39–41	Fault-finding another engineer's code; implementing a ten-clause specification; a twelve-clause unattended machine with no hints

Safety is woven through, not bolted on: fail-safe (NC) wiring, why a guard must break a latch rather than gate an output, contactor interlocking, anti tie-down, and why an E-stop goes through a hardwired safety relay as well as the PLC.

The six sessions

Session 1 — Relay logic is ladder logic

Levels 1–4

Start on the board, not the screen. Draw a rung by hand, the way it has always been drawn. Then show that the software draws the same thing.

Discuss: what does normally open actually mean — normally when?
A trap worth walking into: ask them to make a lamp come on when a sensor is off, before you introduce the NC contact. Let them struggle for two minutes.
Assess: can they read a rung aloud as a sentence?

Session 2 — Memory, and the most important rung in the industry

Levels 5–6

The seal-in. If a student has ever wired a DOL starter, this is the session where the penny drops.

Bring a contactor in if you have one. Point at the auxiliary contact. Then point at the same contact on the screen.
Discuss: why do machine builders prefer a seal-in to Set/Reset coils?
Assess: can they build it from a blank rung, unaided?

Session 3 — Fail-safe, and the difference between working and safe

Levels 7–8

The E-stop signal reads TRUE when healthy. This is the single most important concept in the module.

Discuss: a fork truck cuts the cable to an E-stop. What happens on an NO-wired circuit? On an NC-wired one?
Extend: why does a real machine also have a hardwired safety relay?
Assess: given a signal, can they say whether it needs an NO or an NC contact in the program, and why?

Session 4 — Time and quantity

Levels 9–14

The one-shot is the first genuinely counter-intuitive idea. Spend time on the scan cycle before you spend time on the P contact.
Star-delta is a natural group task and a natural link to a machines unit.
Assess: can they explain why a rising edge lasts exactly one scan?

Session 5 — Machines

Levels 15–18

Two-hand control is a strong discussion: why is "both buttons pressed" not enough?
Hysteresis links directly to any process-control content you teach.
Assess: can they say what goes wrong on a machine with no deadband?

Session 6 — The other three languages

Levels 19–28

One session, deliberately shallow. The goal is recognition, not fluency: none of them should be frightened by a block of Structured Text on a screen in an interview.

Point out that switching a network from LAD to STL in real software is one click, and is the fastest way to learn STL.

Beyond — independent work

Levels 29–41

Ten applied jobs and three certification levels. This is where the students who are genuinely interested separate themselves — which is exactly what you want to see before you write a reference.

Assessment and evidence

Every level ends in an automated commissioning test. Passing is unambiguous, and a failure names the assertion that failed in plain English.
Stars record how they passed: one for working, one for tidy (at or under a par element count), one for unaided.
Completing everything produces a certificate with a completion record and a reference code. Students can print it for a portfolio, or copy the record as text to send to you.

The grading is client-side. It is honest evidence of effort and understanding; it is not tamper-proof, and it should not be used as a controlled assessment. A ninety-second check that cannot be faked: ask a student to talk you through a rung they built.

Mapping to qualifications

We have deliberately not claimed alignment to any specific qualification, because we are engineers rather than awarding-body specialists. The outcomes table above is written so you can map it to your own unit codes in an afternoon.

Vocabulary and conventions lean Siemens (%I0.0, SCL, STL) because that is what much of the UK manufacturing base runs — but everything in chapters 1–3 is platform-neutral.

Data and safeguarding

No accounts, no cookies, no analytics, no tracking. Progress is stored in the student's own browser and never transmitted. The only contact route in the site is an optional careers form on the final certificate, restricted to over-18s. Full detail on the privacy and data page, written to be sent straight to an IT or safeguarding lead.

Talk to us

If you use this with a group, or want to talk about work experience, site visits or apprenticeships for your students, we would like to hear from you. richard.pearson@prizm-technical.co.uk

Built and maintained by Prizm Technical. We are a working consultancy, not a training company. This exists because we would rather more people could do this job.