Motion and state
Its rotary state can be driven from a PLC output so speed and direction remain visible during a scan.
PLC control pattern
Commission it by proving setpoint before accepting the next sequence state.
Fault practice
Inject stuck-on, stuck-off states and require the PLC sequence to detect, stop and recover deliberately.
PLC integration guide
How to use a potentiometer with a PLC
Wire a stable voltage-divider circuit
Connect the two end terminals across the approved reference and common, with the wiper feeding the voltage input. Confirm the analog module input range and common arrangement before energising. A potentiometer is not a universal current-loop source. Cable shielding, separation from motor conductors and a clean reference reduce noise; a broken wiper can otherwise leave the input floating at an unpredictable value.
Scale raw counts into a meaningful setpoint
Use the module raw minimum and maximum—not assumed generic values—to convert the input into percent, speed, pressure or another bounded unit. Clamp outside the intended range and show both raw and scaled values during commissioning. Decide whether zero volts means a valid zero command or a wiring fault; adding end resistors or a restricted valid band can make open or short circuits easier to distinguish.
Filter without making the control feel broken
Small raw fluctuations can make an HMI value or speed command hunt. A modest low-pass filter or deadband can stabilise the setpoint, but excessive filtering creates lag after the operator turns the knob. Keep safety limits and equipment constraints downstream of the operator request so no potentiometer position can demand an invalid operating condition.
Learn the physical principle first
The reference above focuses on PLC integration. The interactive school lesson shows the device, signal or mechanism before you write the control sequence.
Learn how analog signals become PLC valuesSignal map
I/O you can reason about
PLC input Setpoint (%)
| Signal | PLC direction | Type / range |
|---|---|---|
| Setpoint value | input | float · % · 0–100 |
Field checklist
Commissioning sequence
- 01Confirm potentiometer resistance, power rating, taper and analog-module voltage range.
- 02Measure reference-to-common voltage and verify the wiper moves smoothly across the intended span.
- 03Record raw PLC counts at the minimum, midpoint and maximum positions.
- 04Scale, clamp and display the engineering value, then test response and required deadband.
- 05Open the wiper and short it to each rail using an approved test method; verify the program detects or safely bounds each fault.
Fault finding
Symptoms and first checks
| Symptom | Check |
|---|---|
| Value jumps while turning | Inspect a worn wiper, loose terminal, noisy reference, grounding, shielding and raw-count filtering. |
| Only part of the range is available | Check end-terminal voltage, input range configuration and the raw scaling endpoints. |
| Value rises when the knob is turned down | Swap the end terminals or reverse the scaling consistently; do not hide an undocumented wiring convention. |
Fault and recovery exercise
Make abnormal states part of the sequence
Inject stuck-on, stuck-off states and require the PLC sequence to detect, stop and recover deliberately.
stuck-onstuck-off
Engineering boundary
The model teaches PLC sequence behaviour and diagnosis. Confirm ratings, wiring, guarding, process calculations and commissioning limits against the real manufacturer documentation and site design.
Plain-English answers
Potentiometer FAQ
Can a potentiometer connect to a 4–20 mA input?
Not as a plain voltage divider. Use the correct voltage input or an appropriate signal-conditioning circuit designed for the current-loop channel.
What potentiometer resistance should I use?
Use the range recommended for the analog source and module so loading, current and noise remain acceptable. Common values are not a substitute for the module manual.
How can the PLC detect a broken potentiometer wire?
A restricted valid voltage range, bias network or dedicated diagnostics can make open-wire values identifiable. The exact method depends on the input hardware and risk.
Free first success
Put the potentiometer into a working control sequence
Open a related browser scenario, run the PLC logic and see the component state respond. Start without installing software or entering a card.
No installNo credit cardImmediate pass/fail feedback
Keep building
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