New-Tech Europe Magazine | July 2019 | Digital Edition

In other, less demanding machine vision applications, 5GBASE-T is a more cost-effective solution (Table 1 below). For ranges of line-scan and area array cameras, vendors offer support for GigE Vision, an interface standard developed in 2006 by a consortium of mainly camera companies and now administered by the Automated Imaging Association (AIA). Embracing GigE Vision and GenICam GigE Vision provides a framework for transmitting high-speed video and related control data over Ethernet networks, making it easier for developers to build software. As part of the standard, GigE Vision’s GigE Device Discovery Mechanism provides mechanisms to obtain IP addresses and an XML description file that allows access to camera controls

Figure 4: With the need for PCIe frame grabbers, CXP and Camera Link systems can offer very low latency and low jitter camera-to-computer connec- tions. However, frame grabbers limit the number of camera connections (CXP max 8 cameras per card, Camera Link max 2 camera per card), increase costs, and reduce system flexibility. The GigE Vision interface allows for ver- satility when connecting many devices in a system, and has a maximum cable length of 100m.

and image streams that is based on the GeniCam standard developed by the Verband Deutscher Maschinen- und Anlagenbau (VDMA; Frankfurt am Main, Germany). While GenICam exposes features of a camera (such as frame rate) through a unified API and GUI, each

feature is defined in an abstract manner by its name, interface type, unit of measurement and behaviour. The GenApi module of the GenICam standard defines how to write a camera description file that describes the features of a device, how to be interoperable, and uses

Table 1: Interface Comparison

Relative System Cost

Requires Frame Grabber

Features

Cable Required

Interface Max Data

Transfer Speed Max Length Power over Cable

Camera Link

Deterministic, Latency in 4µs Deterministic Latency (approx 4µs)

Shielded twisted pairs, MD-26 connectors RG59 and RG6 75Coax BNC or DIN 1.2/2.3 connectors (camera) Micro-BNC (frame grabber) USB-type-A and USB-C connectors, USB cable USB-type-A and USB-C connectors, USB cable CAT 6a or CAT 6 cable, optical cabling

850 MBytes/s 10m maximum, 7m (Deca)

Yes (PoCL)

Yes

High

100m at 3.125 Gbit/s, 35m (max) at 12.5 Gbit/s

CoaXPress 12.5 Gbit/s Per CXP Link

Yes (PoCXP)

Yes

High

Up to 5 Gbit/s (after overhead 360 MBps)

USB 3.1 Gen 1

5m

Yes (5V, 2.5W)

No

Low Average latency 30 μs

USB 3.2 Up to 20 Gbit/s

3m

Yes (5V, 4.5W)

No

Low Average latency 30 μs Medium Average latency 3μs Low Average latency 3μs

55m (CAT 6) 100m (CAT 6A)

Possible but not implemented Power over Ethernet (802.3bt) Power over Ethernet (802.3bt) 4-pair PoE (51W) 13W (after losses) CAT 3/CAT 5

10GBase-T

10 Gbit/s

No

5GBase-T

5 Gbit/s

100m (CAT 6)

No

CAT 6 cable

2.5Gbase-T 2.5 Gbits/s

100m (CAT 5a)

No

Low Average latency 3μs

CAT 5a cable

100m (CAT 5 cable or better)

1GBase-T

1Gbit/s

No

Low Latency of 1μs to 12μs

CAT5 Cable

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