A legacy capture card used to be the only way to put a live camera image on a second monitor: camera into a PCI grabber, grabber driver onto the PC, and a hunt for a driver that still installs on the operating system you actually run. Every machine-vision camera sold now digitizes on board and streams over one Ethernet or USB 3.0 cable, and the viewer window behaves like any other window — you drag it to the second screen. This guide gives you the numbers to decide between a direct camera-to-viewer link and a frame grabber, a worked example for a microscope bench, and the checks to run before ordering anything. It is for anyone building or modernizing a bench where an operator watches the live image while the PC runs the inspection.
The display path runs PC to monitor, with or without a grabber
A frame grabber never drove a monitor directly, even in the legacy chain. The path has always been camera, grabber, PC, graphics output, monitor, and the driver that made the card visible to the PC was the fragile link. That is why one viewer worked on a card while another failed: each application needed that grabber's SDK, so SDK support, not the hardware, decided what ran. The frame grabber SDK guide breaks down exactly how that split appears on the bench.
Modern area scan cameras removed that link. A GigE Vision camera streams over one Ethernet cable into a standard NIC; a USB3 Vision camera streams over one USB 3.0 port. The viewer window is an ordinary window: extend the desktop to the second monitor and drag it across. For these interfaces the grabber has left the display path entirely, and the fix for an aging analog chain is to replace it, not to find its driver — the move from an analog NTSC grabber to USB3 Vision shows that swap end to end in this replacement guide.
What one cable carries
Work the payload against what one link moves. These are the practical ceilings we plan around:
- GigE Vision on a 1 Gbit/s link: 125 MB/s line rate, about 110 MB/s of image data once protocol overhead is paid.
- USB 3.0 at 5 Gbit/s: roughly 350–400 MB/s of payload.
- 10GigE: about 1,000 MB/s of payload.
- One CoaXPress CXP-6 link: about 600 MB/s of payload.
Display example: a 1080p monitor fed at its full 60 Hz refresh in mono 8-bit needs 1920 × 1080 × 1 byte = 2.07 MB per frame, and 2.07 MB × 60 fps = 124.4 MB/s. That sits above one GigE link's 110 MB/s, so full-rate 1080p display belongs to USB 3.0. At 30 fps the same feed needs 62.2 MB/s and fits GigE with margin. On a microscope bench the scene is still between adjustments, so 30 fps already reads as continuous to an operator.
Worked example: a 12 MP microscope feed on each link
The LS-CMR-0053 is a 12 MP GigE area scan camera with a 1/1.7" IMX226 rolling-shutter sensor, streaming at 9 fps. The camera's rate is the link's rate: 12 MP × 1 byte = 12 MB per frame, and 12 MB × 9 fps = 108 MB/s, right at GigE's practical ceiling. On the display side, a 4K monitor shows 3840 × 2160 = 8.3 MP, so this feed over-samples the screen about 1.4 times. The operator can zoom into a region and still read detail the monitor alone cannot show at 1:1, which is the real reason a bench camera carries more pixels than the screen.
The LS-CMR-0166 carries the same 1/1.7" IMX226 sensor over USB 3.0 and streams 4000 × 3000 frames at 30 fps. The budget: 4000 × 3000 × 1 byte = 12 MB per frame, and 12 MB × 30 fps = 360 MB/s. One GigE link cannot carry that stream; USB 3.0 does, near the top of its 350–400 MB/s range, with little headroom left on that controller for a second camera.
| Specification | LS-CMR-0053 | LS-CMR-0166 |
|---|---|---|
| Resolution | 4000 px x 3000 px | 4000 × 3000 (12MP) |
| Pixel size | 1.85 μm x 1.85 μm | 1.85 μm |
| Max. frame rate | 9 fps | 30 fps |
| Sensor model | IMX 226 | Sony IMX226 |
| Shutter | Rolling Shutter | rolling shutter |
| Data interface | GigE | USB 3.0 |
| Pixel bit depth | 8 / 10 / 12 bits | 10-bit |
| Price | $560.00 | $560.00 |
All 2 share: Sensor size 1/1.7". Values as printed in each product's data sheet; open a part for its drawing and full specifications.
Which interface the display task needs
Turn the rule around to get the frame rate a GigE link supports: fps ≈ 110 MB/s ÷ MB per frame. A 2 MP mono 8-bit stream at 2 MB per frame runs about 55 fps; a 5 MP stream runs about 22 fps; the 12 MP camera above runs 9 fps. Color triples the byte count and divides those rates by three.
| The display must show | Interface to pick | Why the numbers work |
|---|---|---|
| A still or slow microscope scene at full resolution | GigE Vision | 9–22 fps reads as smooth when the part is still; one PoE cable, 100 m of reach |
| Hand-held parts, a moving stage, any real motion | USB3 Vision | 350–400 MB/s holds a 12 MP stream at 30 fps, or 5 MP at about 70 fps |
| Full-motion color at 1080p60 | USB3 Vision or 10GigE | 1920 × 1080 × 3 bytes × 60 fps = 373 MB/s, past GigE |
| Deterministic triggered capture that also needs viewing | CoaXPress through a frame grabber | capture timing drives the choice; the display follows |
Where a frame grabber is still the right part
The camera speaks an interface the PC lacks
Camera Link, CoaXPress and analog composite cameras attach through cards because PCs ship no port for them. Capture on those interfaces is configured on the card rather than in a network stack, and the settings differ enough to deserve their own walkthrough — see frame grabber image acquisition for Camera Link and CoaXPress. For a CoaXPress cluster, the MV-GX1008 is an octo-port CXP-6 frame grabber that takes eight camera links on one card.
- Interface
- CoaXPress
The host needs more or faster ports
A GigE camera runs on any working NIC, but a bench with several cameras wants dedicated ports: the MV-GE2002P is a dual-port PoE GigE NIC that adds two camera ports and powers both cameras over the same cables. The tuned driver matters as the camera count grows — the GigE Vision high-performance NIC driver guide measures what it adds. Past 110 MB/s per camera, the MV-GT2104 is a quad-port copper 10GbE NIC for four 10GigE camera links.
- Interface
- GigE
- Ports
- 2 ports
- Interface
- 10GigE
- Ports
- 4 ports
One stream per camera
A camera serves one consumer at a time. If the viewer on the second monitor and the inspection program both need the image, route both through the application that owns the camera, or assign cameras to ports deliberately — the port assignment guide shows the method. And if the display PC is a laptop, confirm the whole interface chain before ordering cards: the laptop compatibility guide lists what to check.
Bring the live window up on the second monitor
- In the operating system display settings, extend the desktop to the second monitor rather than mirroring it, so the viewer can own that screen.
- Start your GenICam-compliant viewer or SDK grab loop and connect by the camera's unique identifier so no other device takes the handle — the connect, capture and save walkthrough for GigE Vision cameras over Ethernet shows the sequence.
- Set the pixel format to the smallest the task allows: mono 8-bit moves 1 byte per pixel against 3 for color, and a display-only stream rarely needs more.
- Size the viewer window to fill the second screen and keep the camera ROI as small as the task allows; window sizing and screen placement have their own settings — the vision display window guide covers them.
- Read the fps counter against the link budget: MB per frame × fps must stay under the figures in the table above, or frames drop mid-display.
On a grabber-based bench that shows no image at all, check cabling before software: the frame grabber wiring checks resolve most no-image cases.
Checks before you order
- Host slots and ports: count free PCIe slots and USB 3.0 ports before choosing interfaces, not after.
- Cable runs: GigE reaches 100 m on one cable; USB 3.0 is dependable at about 3 m passive, longer only with active optical cables.
- Power: a PoE NIC feeds the camera over the Ethernet cable; a non-PoE port means a separate power supply.
- Headroom: add up every planned stream on a link and keep 20% margin under the payload figures above.
- Monitor: any monitor follows the PC's graphics output; 60 Hz is standard and no capture hardware sits in between.
- Trigger plans: if display-only will grow into inspection, choose an interface that carries trigger wiring now.
If the bench should host both the PC and the screen in one unit at the station, an industrial panel PC replaces the tower-plus-monitor pair, and the camera chain stays identical.
When the usual answer is wrong
Give the camera its own NIC and subnet. A camera hung off the office switch shares its stream with every other packet in the building, and the jitter lands exactly on the video you are watching. A grabber will not make a GigE camera faster either: the ceiling belongs to the camera and the link, so the card adds ports and interfaces, not bandwidth a camera does not have. And more display frames per second will not fix a detail problem — if the operator cannot resolve the feature at full-screen zoom, the answer is optics and sensor resolution, not interface speed. More systems guides cover the rest of the acquisition chain.
So the decision, per case: a GigE camera and a PoE NIC when the scene is still and resolution rules; USB 3.0 when motion or 30 fps at 12 MP matters; a frame grabber only when the camera's interface leaves no other path. Pick the camera in the camera finder, the ports in the accessories finder, or start at the system configurator — we will check the link budget with you before the order.
Questions
Can a machine-vision camera show a live image on a monitor without a capture card?
Yes, for any GigE Vision, USB3 Vision or 10GigE camera: the sensor is digitized in the camera, the SDK viewer or your code displays the stream, and the monitor hangs off the PC's graphics output as always. Camera Link, CoaXPress and analog cameras are the exception — they need a card in the PC because the host has no such port.
How many frames per second will one GigE camera deliver to the screen?
Divide about 110 MB/s by the frame size in MB. Mono 8-bit gives roughly 55 fps at 2 MP, 22 fps at 5 MP and 9 fps at 12 MP. Color divides those rates by three. The camera must also be rated for the figure you pick: a camera listed at 9 fps never exceeds it, whatever the link allows.
Does the monitor's 60 Hz refresh rate limit the camera frame rate?
No. Acquisition and display run independently: the viewer takes the newest completed frame and draws it on the next refresh. A 60 Hz monitor can show at most 60 distinct frames per second, so a 9 fps stream updates nine times a second and holds the last image between updates — no frames are lost, they are simply not acquired.
Can the viewer on the second monitor and my inspection software share one camera?
A camera serves one stream at a time. Run the display through the application that owns the camera, rendering its window onto the second screen, or give the display its own camera and port. In multi-camera benches, assign each camera to a dedicated NIC port and connect by unique identifier so the handles never swap.
How long can the camera cable to a bench-mounted monitor station be?
GigE Vision runs to 100 m on a single Ethernet cable, which covers most buildings. USB 3.0 is dependable at about 3 m passive; longer runs need active optical cables. If the bench sits far from the host, that distance alone usually decides the interface before bandwidth does.