Application of DVT machine vision system for industrial online inspection

The DVT machine vision system is a computer system that can replace the human eye. It is researched and developed to adapt to the detection and monitoring of image and character automated production lines. In the high-speed, batch, and continuous automated production process, a vision system is often needed for OCR character and various number recognition, quality inspection, color and geometric shape recognition, and size measurement. In fact, in developed countries, the production of almost any product, from bills, securities printing, semiconductor manufacturing, to food, beverage, and pharmaceutical packaging, is increasingly dependent on the application of vision systems. Through value-added development on the basis of international software and hardware platforms, DVT can provide a variety of online or offline visual inspection solutions with extremely high performance and price ratio.

2. Working principle

The Legend 630 series of intelligent image sensors have comprehensive functions and built-in Ethernet interface, which can communicate with your existing equipment at will for remote diagnosis and remote management.

Legend630 is a machine vision that uses CMOS imaging technology for complete machine vision inspection. It integrates all hardware in a compact unit. It is a typical embedded structure. It uses a Motarola Power PC processor and has 16M RAM and 4M flash memory. , External interface and digital I/O port, the resolution of the image sensor reaches 640×480; it can work independently without other computers or image capture cards. FrameWork is a software platform for managing and operating DVT SmartImage Sensors. It has three main components: one is the FrameWork user interface that runs on the PC and needs to be installed by the user. The second is to run the embedded part of the FrameWork firmware on the DVT510. The DVT630 is pre-installed when it leaves the factory. The third is the Firmware simulator, as long as the image is stored in the PC, it can be tested offline. The user writes the program and sets the parameters on the FrameWork user interface, and then enters the embedded structure of the DVT630, so that the DVT630 can work independently.

3. Communication driver

The communication between the smart image sensor camera and external devices such as PLC and motion controller can be completed by one or several drivers. There are two main schemes for outputting data from the camera to the peripherals: 1) Synchronization, the data transmission format without query is ASCII text. 2) Asynchronous, query data transmission from the shared memory space of the register. In the former case, data is transmitted through the DataLink interface after each detection. In the latter case, by using registers, data reading and writing are independent of the detection loop. As shown in Figure 1:

Application of DVT machine vision system for industrial online inspection
1) Synchronous data transmission

① System driver The system driver is used for system-specific communication between the intelligent image sensor hardware (or emulator) and the FrameWork user interface. Here introduce the system driver from PC-based software (Visual Basic program) to intelligent image sensor communication.

②DataLink driver

The DataLink driver is mainly used for the communication between the output of the camera and the external device of the smart image sensor. DataLink allows users to configure the ASCII string that is output after the test is completed. Configure the serial port of the camera to use the DataLink driver. Select the comm menu and choose to use the DataLink terminal driver in the terminal characteristics dialog box. Select DataLink in the I/O menu to configure the ASCII string in DataLink.

③For synchronous output data, it can also communicate through the hyper terminal on the PC. In addition, you can run the telnet.exe program to connect the IP Address and port number to transmit data.

2) Asynchronous data transmission

①Modbus driver

The script running on the smart image sensor writes data into the register of the sensor memory. Script soft sensor and detection are synchronous, background script and detection are asynchronous. Through the modbus protocol, the data in the smart image sensor can be transmitted to the smartlink. This is a cyclic process, and the image sensor reads and writes smartlink like the host. , The data in smartlink is exchanged cyclically with the profibus network. The data transmission process is shown in Figure (2).

Application of DVT machine vision system for industrial online inspection
Ⅰ) Use script soft sensor to manage registers

One command in the Script program is to write the radius of the small hole to the No. 100 register of the smart image sensor. The second command is to read the data of the No. 200 register, multiply the data by 2×3.14 and assign it to the perimeter of the script sensor output hole. Then this value can be displayed in the result table. See figure (3).

Application of DVT machine vision system for industrial online inspection
Application of DVT machine vision system for industrial online inspection
Ⅱ) Establish a Modbus host

Establish Modbus data exchange, so that the smart image sensor can exchange data with SmartLink cyclically, so it can also exchange with the Profibus host. The smart image sensor is used as the master to control the data exchange with the slave (SmartLink). See figure (4). The data result on the DVT register can be transmitted through a serial interface connection or an Ethernet connection. The port number of the Ethernet connection is 502.

Application of DVT machine vision system for industrial online inspection
②Motoman drive

When using the Motoman XRC controller, you should use the Motoman serial port driver, the sensor interface protocol of the Motoman controller implemented by the Motoman driver.

③Fanuc drive

When using Fanuc RJ-2 or RJ-3 controller, you should use Fanuc serial driver, Fanue driver implements Fanuc's sensor interface protocol on Fanuc controller.

4. SmartLink user interface

The SmartLink project is developed on a PC using the SmartLink user interface. A SmartLink project includes information about monitoring applications running in SmartLink. Start the SmartLink user interface, open the emulator, and the image information obtained from the smart image sensor can be displayed on the PC. When the monitoring project works as expected, transfer the project to the actual SmartLink via Ethernet or serial port. When the project is running, the information is displayed on the monitor connected to the SmartLink video output terminal. As shown in Figure (5)

Application of DVT machine vision system for industrial online inspection
5 Conclusion

The article discusses the online detection based on the DVT smart sensor industry. According to different detection requirements, the corresponding soft sensor can be selected in the FrameWork interface, and the detection result is displayed in the result dialog box. The data transmission of the intelligent image soft sensor can realize synchronous transmission without query or asynchronous data transmission on request, and the data processing is flexible, convenient and fast.