Banner iVu — Output/Trigger Polarity & Remote Teach

Banner Engineering · beginner · 20 min

When a Banner iVu sensor's Pass/Fail output or trigger seems wrong, it's usually PNP/NPN polarity or the input transition direction — plus a missing pull-up on NPN triggers. Set the Input Polarity to match your wiring.

ℹ️ The iVu doesn't know how you wired it — you tell it. Almost every 'output backwards' or 'won't trigger' case is a PNP/NPN polarity setting that doesn't match the actual wiring.

Pass/Fail output polarity

On a Banner iVu image sensor, the Pass/Fail output electrical setting determines whether the output is active on Pass or on Fail, and the default depends on the sensor type:

  • PNP default: Low to High.
  • NPN default: High to Low.

If your PLC reads the output inverted (fails look like passes), the Input Polarity setting doesn't match your wiring/logic — change it on the Input Polarity screen so the output edge matches what the PLC expects.

Trigger and Remote Teach inputs

The iVu has two input signals: Trigger and Remote Teach, and Remote Teach behaves electrically like Trigger. Their active edge also depends on sensor type:

  • PNP sensors detect Trigger / Remote Teach on the low-to-high transition.
  • NPN sensors detect Trigger / Remote Teach on the high-to-low transition.

So if the sensor won't trigger (or won't accept a remote teach), confirm your signal makes the correct transition direction for your PNP/NPN version.

The NPN pull-up gotcha

If you're using an NPN trigger source, you must add a pull-up resistor (~1 kΩ) on the trigger line per the iVu wiring instructions. Without it, the NPN trigger edge may not be seen and the sensor appears to ignore triggers.

Inconsistent pass/fail results

If the sensor triggers and outputs but the results are inconsistent (same part sometimes passes, sometimes fails):

  1. Review the inspection job settings in the iVu software — thresholds, ROI, and tolerances that are too tight cause borderline parts to flip.
  2. Make part presentation consistent — fixture the part, stabilize lighting, and keep the working distance/angle repeatable so each image is comparable.

Step-by-step

  1. Output looks inverted? Set the correct Input Polarity (PNP Low→High / NPN High→Low) so the Pass/Fail edge matches the PLC.
  2. Won't trigger? Confirm the trigger signal makes the correct transition for your PNP/NPN version, and for NPN add the ~1 kΩ pull-up.
  3. Remote teach not working? It's electrically like trigger — same polarity/edge rules apply.
  4. Inconsistent results? Tighten fixturing and lighting and review the job thresholds.

When it's really hardware

Once polarity, trigger edge, pull-up, and presentation are correct, a sensor that still won't image points to the lens, lighting, or the sensor — check the live image in the iVu display before replacing anything.

Key points

  • Pass/Fail output default polarity is PNP Low→High and NPN High→Low — set Input Polarity so the edge matches the PLC.
  • The iVu has Trigger and Remote Teach inputs; Remote Teach behaves electrically like Trigger.
  • PNP triggers on low-to-high, NPN on high-to-low — a wrong transition direction looks like 'won't trigger.'
  • An NPN trigger source needs a ~1 kΩ pull-up resistor or the edge may not be detected.
  • Inconsistent pass/fail usually means loose fixturing/lighting or too-tight job thresholds, not a bad sensor.

Codes and symptoms

Output inverted — Wrong Pass/Fail polarity
The Input Polarity setting (PNP Low→High / NPN High→Low) doesn't match the wiring, so Pass/Fail reads backwards.
No trigger — Trigger not detected
Wrong transition direction for the PNP/NPN version, or a missing ~1 kΩ pull-up on an NPN trigger source.