Camera for Counting on a Conveyor or Packing Line: Spec (px/m, fps, angle)
Can a camera count what comes off your conveyor? Yes, for separate items that fill at least about 32 px in the analysed frame, mounted straight down. As of 15 Oct 2026, 4 MP CP Plus datasheets list 1–25/30 fps (25 in PAL mode), enough for 400 mm cartons at 0.3 m/s, not for 50 mm pouches at 1 m/s.
Last checked: 15 Oct 2026. Line layouts and speeds are worked assumptions; everything else is sourced. Nobody tested a camera for this page.
Verified against
- IEC 62676-4:2014 pixel densities (25 / 62.5 / 125 / 250 px/m), quoted in the foreword of IEC 62676-4:2025, ed. 2.0, published 9 Oct 2025 (STN EN IEC 62676-4:2026 preview; IEC webstore).
- COCO detection evaluation: "small objects: area < 32²" pixels (cocodataset.org; cocoeval.py).
- Ultralytics YOLO predict mode, default
imgsz640 (docs). - Texas Instruments, Light That Freezes Motion, SSZT704, May 2018 (PDF).
- Basler, Electronic shutter types.
- CP Plus datasheets: CP-UNC-DA41L3C-Q (19-08-2025), CP-UNC-DA21L3C-Q (05-08-2026), CP-UNC-VC41ZL5C-VMD-Q (24-09-2026), CP-UNC-DA61L3C-LQ (08-07-2026).
- Hikvision, H.264(5) & H.264(5)+ Recommended Bit Rate at General Resolutions (archive copy).
- Checked 15 Oct 2026.
Task per view → pixel density
DORI levels were written for people. For counting objects, the number that matters is pixels across the object.
| Task at the line | What to plan for | px on target | Basis |
|---|---|---|---|
| Is the line running or stopped? | Detect (people) / belt motion | 25 px/m | IEC 62676-4:2014 values |
| How many people at the line? | Observe | 62.5 px/m | IEC 62676-4:2014 values |
| Count discrete items | Smallest side of the item ≥ 32 px in the analysed frame | 32 px per item | COCO "small" line (assumption that it applies to your items) |
| Read a label or date code | Not a CCTV task | — | Use a scanner or vision sensor |
COCO scores objects under 32 × 32 px separately as "small". Keeping every counted item above that line is our assumption, not a standard rule.
Required px/m = 32 ÷ object size (m). A 400 mm carton needs 80 px/m, a 150 mm box 213 px/m, a 50 mm pouch 640 px/m. The method for people levels is in the DORI explainer.
The trap: px/m in the analysed frame, not the sensor
Counting software rarely sees the 2688-px main stream. Ultralytics YOLO resizes frames to 640 px by default, and the CP Plus DA41L3C-Q sub stream tops out at 1280 × 720.
So compute px/m with the width the software analyses: PPM = R_analysed ÷ W, where W = 2 · d · tan(HFOV/2). For R = 640 and 32 px per item, the scene can be at most 20 × object size wide: 1.0 m for a 50 mm pouch, 8 m for a 400 mm carton. Run your own numbers in the lens and DORI calculator.
Speed → fps and shutter
- Travel per frame = speed ÷ fps. For an overlap-based tracker, keep it under half the item length (assumption): fps ≥ 2 · speed ÷ object length.
- Blur (px) = speed × exposure × px/m. Texas Instruments (SSZT704) calls ≤ 1 px blur "the best approach to freezing motion" for inspection. Counting tolerates more; we assume blur ≤ 10% of item length: exposure ≤ 0.1 · length ÷ speed.
- Flicker limit: under 50 Hz mains, light ripples at 100 Hz, so whole-cycle exposure is 1/100 s (10 ms). Anything shorter needs flicker-free lighting over the belt (flicker fix).
| Item (mm) | Belt speed (m/s) | px/m needed | Travel at 25 fps (mm) | Min fps | Max exposure (ms) | Works at 25 fps, 1/100 s? |
|---|---|---|---|---|---|---|
| 50 | 0.3 | 640 | 12 | 12 | 16.7 | Yes |
| 50 | 1.0 | 640 | 40 | 40 | 5.0 | No: fps and flicker |
| 50 | 2.0 | 640 | 80 | 80 | 2.5 | No: CCTV is the wrong tool |
| 150 | 0.3 | 213 | 12 | 4 | 50 | Yes |
| 150 | 1.0 | 213 | 40 | 14 | 15 | Yes |
| 150 | 2.0 | 213 | 80 | 27 | 7.5 | No: needs > 25 fps and < 10 ms |
| 400 | 0.3 | 80 | 12 | 2 | 133 | Yes |
| 400 | 1.0 | 80 | 40 | 5 | 40 | Yes |
| 400 | 2.0 | 80 | 80 | 10 | 20 | Yes |
The CP Plus 4 MP models list main stream at "1-25/30fps"; the 6 MP DA61L3C-LQ drops to 20 fps at full resolution. Per the CP Plus LQ web manual v1.0.3, PAL gives 1–25 fps; 30 fps needs NTSC. On 50 Hz mains, plan on PAL, 25 fps, Anti-flicker 50Hz. All four datasheets list manual shutter from 1/3 s to 1/100,000 s.
None of the four CP Plus datasheets states a global shutter; they list "PS CMOS" sensors (checked 15 Oct 2026). Basler notes that with a rolling shutter "image distortion may occur" on fast objects. A sheared carton still counts.
Worked spec for a typical Indian packing line
Assumptions: belt top 0.9 m above floor, one lane, items separated, LED battens on 50 Hz mains. Camera looks straight down from a gantry bracket.
| View | Example camera (datasheet) | Pixels × HFOV | Height above belt | Scene (m) | px/m full / at 640 | px per item at 640 | fps, shutter | Verdict |
|---|---|---|---|---|---|---|---|---|
| A. Cartons 400 mm at 0.3 m/s, line end | CP-UNC-DA41L3C-Q, 3.6 mm | 2688 × 78° | 2.0 m | 3.24 | 830 / 198 | 79 | 25 fps, 1/100 s (2.5 px blur) | Fits |
| B. Boxes 150 mm at 1.0 m/s, case packer infeed | CP-UNC-DA21L3C-Q, 3.6 mm | 1920 × 86° | 1.6 m | 2.98 | 643 / 214 | 32 | 25 fps, 1/100 s (10 mm blur) | Fits at the limit |
| C. Pouches 50 mm at 1.0 m/s, after the FFS machine | CP-UNC-VC41ZL5C-VMD-Q set ~35° | 2688 × 35° | 1.6 m | 1.01 | 2664 / 634 | ≈32 (31.7) | needs ≥ 40 fps and ≤ 1/200 s | Fails: datasheet max 25/30 fps |
For view C, count from the machine's own cycle counter or a photo-eye, and use the camera to see why the machine stopped (FFS micro-stops).
Mounting height: 1.6–2.0 m above the belt (2.5–2.9 m from the floor here): above operators' heads, low enough to keep the scene under 20 × item size.
Camera count: one per count point, not per metre. Typical points: after the filler, at the case packer, at line end. A belt wider than the scene, or several lanes, needs one camera per lane.
IP/IK: all three example models list IP67; neither fixed dome lists an IK rating (the VC41ZL5C-VMD-Q lists IK10). Over a washdown or powder line, check the rating's test meaning in the IP/IK guide.
Light and IR: datasheets print minimum illumination at a stated F-number and 30 IRE, without the shutter used (DA41L3C-Q: 0.03 [email protected] colour). Halving exposure from 1/100 s to 1/200 s halves the light collected. Count with hall lights on; IR bounces off shrink film and glossy cartons.
Storage for 30 days
Per the Hikvision sheet, H.265 at 25 fps is 4,096 Kbps for 2688 × 1520 and 2,048 Kbps for 1080P: 44.2 and 22.1 GB per camera per day. The sheet stops at 30 fps; it has no 50 fps row (checked 15 Oct 2026).
| Cameras on one line | GB/day | 30 days (TB) | 30 days +30% (TB) |
|---|---|---|---|
| Views A + C (4 MP) + B (2 MP) | 110.6 | 3.3 | 4.3 |
The sheet suggests 20–30% more "if the real environment is more complex". See the NVR days table.
What breaks in a factory
- Touching or stacked cartons. Items without a gap merge into one. A side view hides the second carton behind the first; top-down reduces this, it does not remove it.
- Things that move by themselves. Rollers, flaps, a stretch-wrap arm and operators' hands cross the count line too. Anything that moves like a product can be counted as one.
- Stop-start belts. A belt that stops with a carton on the count line, then reverses, double-counts on simple line-crossing logic.
- Rejects after the count line. The camera counts what passed it, not what was shipped. Put the count point after the reject gate.
- Frame drops. At 1 m/s and 25 fps, each lost frame is 40 mm of belt the software never saw.
When to call the installer / what to ask the vendor
Ask which stream and resolution the counting software analyses, whether manual shutter can be locked, and whether the camera holds 25 fps on PAL with anti-flicker on. At handover, measure an item's pixel width in the analysed frame and reconcile one shift's camera count against the machine counter (commissioning checklist).
This page covers counting. Spotting defects is in camera quality control; the packing hall and truck doors are in the packing and dispatch spec, and the dock itself in the loading dock spec.
Mama reads a factory's existing cameras over RTSP/ONVIF and tells the owner, in plain language, when a line ran and when it stood idle (askthemama.com). Leave an email or phone in the form below.
FAQ
Can a CCTV camera count products on a conveyor belt? Yes, for separate items that reach about 32 px in the frame the software analyses, with the camera straight above the belt. Small, fast or touching items are better counted by a photo-eye or the machine's PLC.
What frame rate do I need to count objects on a conveyor? At least 2 × belt speed ÷ item length (our assumption for overlap tracking). For a 400 mm carton at 1 m/s that is 5 fps; for a 50 mm pouch it is 40 fps, above the 25 fps PAL limit of CP Plus 4 MP models (checked 15 Oct 2026).
Why is my camera count different from the machine counter? Usually touching items, rejects removed after the count line, belt stops or dropped frames. Reconcile one full shift first.