PLC Logic by Hand: Contacts & Coils, Seal-In Circuits, the Scan Cycle, Edge Detection, Timers, Counters, Step Sequences & Alarm Handling
Think like a controller, one scan at a time. You will write contacts and coils as 0/1 cells, build start/stop seal-in circuits, solve rungs in scan order, catch rising and falling edges, run on-delay, off-delay and retentive timers, count parts, step a toy machine through a sequence and latch, acknowledge and rank alarms, with every cell checked as you go.
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About this course
This course teaches PLC logic one scan at a time, with every rung written as a 0/1 formula. You solve normally open and normally closed contacts, series and parallel branches and an exclusive OR, then build start/stop seal-in circuits in reset- and set-dominant form. You compare two rung orders to see the one-scan delay and estimate worst-case response times from scan times. You detect rising and falling edges, run on-delay, off-delay and retentive timers in milliseconds, count parts with an up/down counter and MOD, step a toy mixing tank through a sequence and finish with latched alarms, an alarm word, first-out, permissives and a state column.
Lessons
- Contacts and Coils as 0/1 Cells: Normally Open, Normally Closed, Series & Parallel Pro
- Seal-In Circuits: Start/Stop with a Holding Contact, Scan by Scan Pro
- The Scan Cycle: Read Inputs, Solve Rungs, Write Outputs & the One-Scan Delay Pro
- Edge Detection: Rising and Falling Edges, One Count per Press Pro
- Timers: On-Delay, Off-Delay and Retentive, Milliseconds per Scan Pro
- Counters: Up/Down Counting on Edges, Reset, Box Presets and Wrap-Around Pro
- Step Sequences: A Mixing-Tank Cycle as Numbered Steps and Transitions Pro
- Capstone – Alarms & Permissives: Latch, Acknowledge, First-Out and a State Chart Pro