Motion and state
Its visible state changes with simulated I/O, making status and diagnosis readable in the scene.
PLC control pattern
Commission it by proving tag identifier before accepting the next sequence state.
Fault practice
Inject stuck-on, stuck-off, misaligned states and require the PLC sequence to detect, stop and recover deliberately.
PLC integration guide
How to use a rfid reader with a PLC
Design an explicit request and response handshake
Create states such as IDLE, REQUESTED, BUSY, COMPLETE and FAULT. Pulse or sequence the read request according to the reader interface, then wait for busy or acknowledgement. Accept tag data only when the device asserts data-valid or successful completion. Copy it into a stable application buffer and acknowledge consumption before allowing another request. This prevents repeated scans or half-updated strings from stepping the machine twice.
Separate no tag, bad read and communication loss
No tag in range is often a normal process condition; a checksum failure, unsupported tag, antenna fault or network timeout is not. Map the reader status word into specific alarms and decide which conditions permit retry. Use a bounded retry count and a clear operator recovery path rather than looping forever. When identification controls routing or recipe selection, reject unknown or stale data safely.
Commission the radio zone with the real carrier
Read range depends on frequency, tag orientation, antenna field, metal, liquid, speed and mounting. Test the worst-case tag position on the real product carrier, not just a tag held by hand. Prevent overlapping reader zones from creating ambiguous reads and record enough diagnostic data—reader, station, tag and timestamp—to troubleshoot an intermittent production event.
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.
Practise identification in a conveyor sequenceSignal map
I/O you can reason about
PLC input Tag identifier
| Signal | PLC direction | Type / range |
|---|---|---|
| Tag identifier tag_id | input | int |
Field checklist
Commissioning sequence
- 01Verify reader supply, network identity, antenna configuration and the PLC data layout.
- 02Read one known tag at rest and confirm the PLC receives the complete expected identifier.
- 03Move the real carrier through the field at minimum and maximum production speeds and orientations.
- 04Prove request, busy, done, error and acknowledgement transitions for repeated transactions.
- 05Test no tag, unknown tag, communication timeout and duplicate presentation without double-triggering the sequence.
Fault finding
Symptoms and first checks
| Symptom | Check |
|---|---|
| Reader sees the tag but PLC data is stale | Check data-valid timing, input assembly mapping, byte order, buffer copy logic and acknowledgement. |
| Reads fail only at production speed | Increase valid dwell in the RF field, correct antenna position, reduce interference and confirm transaction time. |
| One tag triggers twice | Require a fresh request cycle or tag-clear state and edge-detect the completed transaction. |
Fault and recovery exercise
Make abnormal states part of the sequence
Inject stuck-on, stuck-off, misaligned states and require the PLC sequence to detect, stop and recover deliberately.
stuck-onstuck-offmisaligned
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
RFID reader FAQ
Should the PLC compare RFID strings every scan?
Use a completed, validated transaction and a one-shot application event. Continuously comparing a live receive buffer can repeat actions or consume partially updated data.
What is the difference between RFID and a barcode?
RFID can read without optical line of sight and may support writable data, but performance depends on radio conditions, tag construction and surrounding materials.
How should an unknown tag be handled?
Do not silently apply a previous identity. Hold or reject the item, record the read and require the defined retry or operator decision.
Free first success
Put the rfid reader 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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