Before understanding data interfaces, let's first understand what an industrial camera is. An industrial camera is a key component in a machine vision system, its most fundamental function being to convert light signals into ordered electrical signals. Choosing the right camera is also a crucial step in machine vision system design. The camera selection directly determines not only the resolution and quality of the acquired images but also the overall system operation. Transmitting the images acquired by the camera requires using the camera's interface to transfer the image data to our equipment.
Industrial camera interfaces include: USB 2.0/3.0, 1394a/1394b, CameraLink, Gige, CoaXPress, etc. Below, we analyze the advantages and disadvantages of each interface.
1. USB interface
USB 1.0: Released in 1996, with a transmission speed of 1.5 Mbps.
USB 1.1: Released in 1998, with a transmission speed of 12Mbps, used in USB mice, keyboards, home scanners, etc.
USB 2.0: Released in 2000, with a transmission speed of 480Mbps, a communication distance of 5m, and 80% of the bandwidth used for image transmission.
USB 3.0: Released in 2008, with a transmission speed of 4.8Gbps, a communication distance of 10m, and 80% of the bandwidth used for image transmission.
USB interface features
It supports hot-swapping and hot-plugging, is easy to use, has a unified standard, can connect to multiple devices, and the camera can be powered via USB cable.
USB limitations
There is no standard protocol or master-slave structure, resulting in high CPU utilization and unreliable bandwidth.
2. IEEE 1394 - FireWire Interface
L1394A: Released in 1995, with a transmission speed of 400Mbps and a communication distance of 4.5m. Primarily used in video transmission.
L1394B: Released in 2002, with a transmission speed of 800Mbps and a communication distance of 4.5m. Primarily used in video transmission.
Features of the 1394 interface
High speed, supports hot-swapping, real-time data transmission, adopts bus structure, plug and play.
3. Cameralink Interface
The Digital Image Signal Communication Interface Protocol (DISIP), developed by the AIA Association, is a serial communication protocol.
It adopts the LVDS interface standard, which features high speed, strong anti-interference ability, and low power consumption.
It evolved from Channellink technology, adding some transmission control signals and defining some related transmission standards on the basis of Channellink technology.
The protocol uses an MDR-26 pin connector.
CamerLink Interface Features
High speed, bandwidth up to 6400Mbps, strong anti-interference ability, and low power consumption.
4. Gigabit Ethernet interface
It was created and promoted by AIA (Automated Imaging Association).
l is a camera interface standard developed based on the Gigabit Ethernet communication protocol.
Suitable for industrial imaging applications, it transmits uncompressed video signals over a network.
The first standard to use inexpensive cables for long-distance image transmission.
Gige interface features
It has good scalability, and the maximum data transmission length can be extended to 100m (which can be extended indefinitely on broadcast equipment).
With a bandwidth of up to 1 Gbit, large amounts of data can be transmitted instantly.
It can use a standard NIC card (or one that is already installed by default on the PC).
It is economical, as it can use inexpensive cables (common Ethernet cables (CAT-6) and standard connectors are acceptable).
It can be easily integrated, and the integration cost is low.
Manageability, maintainability, and wide applicability
5. CoaXPress
lCoaXPress is an asymmetric, high-speed point-to-point serial communication digital interface standard.
Transmission speeds up to 6.25Gbps
Transmission distance exceeds 100m
CoxXPress Interface Features
Large data transmission volume and long transmission distance
Selectable transmission distance and transmission amount:
The bandwidth increased from 50Mbps at 6.25Gbps to 170Mbps at 1.25Gbps.
Low price, easy to integrate, supports hot-swappable
Summary of Industrial Camera Interfaces
Currently, the most widely used interface in machine vision is the Ethernet interface. Ethernet interfaces offer significant advantages over other interfaces in terms of transmission speed, distance, and cost. The image below shows a machine vision system detecting QR codes; the camera interface (yellow line) used is an Ethernet interface.
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