Variable Height Line Scan Acquisition (VHA) Examples
Print
The following examples ship with NI-IMAQ:
LabVIEW:
National Instruments\LabVIEW\examples\IMAQ\IMAQ Signal IO.llb
- LL VHA Ring.vi
CVI:
National Instruments\MeasurementStudio\CVI\samples\imaq\Signal IO
- VHA Ring.prj
Miscrosoft Visual C++:
National Instruments\ni-imaq\samples\MSVC\Signal IO\
- VHA Ring
Variable Height Acquisitions (VHA) are used when the height of objects is not known ahead of time. A common example is a conveyor belt with objects of varying heights passing under the line scan camera. The IMAQ hardware can take an input signal that is high while an object is passing under the camera, and the IMAQ device can combine only those lines from the camera that were acquired while the trigger was high, producing images of different heights depending on how long the trigger was high for the different images.
Make sure to set your maximum expected height in Measurement & Automation Explorer for the acquisition window height.
The following example illustrates additional functionality with VHA.
The first example includes motion and uses the the trigger each line functionality of IMAQ in addition to the VHA triggering. The encoder signal from the motion controller is routed via RTSI to Trigger Each Line of the image acquisition. You can install an external sensor that communicates to the system whether or not an object is present. This code also simulates an environment in which the motion controller periodically breaks down, thereby altering the velocity and acceleration of the motion system. This simulation tests that Trigger Each Line is really using the encoder feedback of the motion system.
The second example demonstrates how to use the counter on an E Series board to control the image acquisition device for Variable Height Acquisition (VHA) mode. The E Series board generates a pulse train that controls the height of the image acquired by the line scan camera. The pulse train is routed to the IMAQ device over RTSI, and the frequency can be changed on the fly.
Filename: 203602.zip
Application Software: LabVIEW Base Development System 6.0
Toolkits and Add-Ons: LabVIEW Vision Development Module 6.1
Language(s): Visual C++, C, LabVIEW
Hardware Group: Vision (IMAQ)
Driver: NI-IMAQ 2.6, Traditional NI-DAQ (Legacy) 6.7.0
Filename: 203601.zip
Application Software: LabVIEW Base Development System 6.0
Toolkits and Add-Ons: LabVIEW Vision Development Module 6.1
Language(s): C, LabVIEW, Visual C++
Hardware Group: Vision (IMAQ)
Driver: NI-Motion 6.0, NI-IMAQ 2.6
LabVIEW:
National Instruments\LabVIEW\examples\IMAQ\IMAQ Signal IO.llb
- LL VHA Ring.vi
CVI:
National Instruments\MeasurementStudio\CVI\samples\imaq\Signal IO
- VHA Ring.prj
Miscrosoft Visual C++:
National Instruments\ni-imaq\samples\MSVC\Signal IO\
- VHA Ring
Variable Height Acquisitions (VHA) are used when the height of objects is not known ahead of time. A common example is a conveyor belt with objects of varying heights passing under the line scan camera. The IMAQ hardware can take an input signal that is high while an object is passing under the camera, and the IMAQ device can combine only those lines from the camera that were acquired while the trigger was high, producing images of different heights depending on how long the trigger was high for the different images.
Make sure to set your maximum expected height in Measurement & Automation Explorer for the acquisition window height.
The following example illustrates additional functionality with VHA.
The first example includes motion and uses the the trigger each line functionality of IMAQ in addition to the VHA triggering. The encoder signal from the motion controller is routed via RTSI to Trigger Each Line of the image acquisition. You can install an external sensor that communicates to the system whether or not an object is present. This code also simulates an environment in which the motion controller periodically breaks down, thereby altering the velocity and acceleration of the motion system. This simulation tests that Trigger Each Line is really using the encoder feedback of the motion system.
The second example demonstrates how to use the counter on an E Series board to control the image acquisition device for Variable Height Acquisition (VHA) mode. The E Series board generates a pulse train that controls the height of the image acquired by the line scan camera. The pulse train is routed to the IMAQ device over RTSI, and the frequency can be changed on the fly.
Requirements
Filename: 203602.zip
Software Requirements
Application Software: LabVIEW Base Development System 6.0
Toolkits and Add-Ons: LabVIEW Vision Development Module 6.1
Language(s): Visual C++, C, LabVIEW
Hardware Requirements
Hardware Group: Vision (IMAQ)
Driver: NI-IMAQ 2.6, Traditional NI-DAQ (Legacy) 6.7.0
Software Requirements
Application Software: LabVIEW Base Development System 6.0
Toolkits and Add-Ons: LabVIEW Vision Development Module 6.1
Language(s): C, LabVIEW, Visual C++
Hardware Requirements
Hardware Group: Vision (IMAQ)
Driver: NI-Motion 6.0, NI-IMAQ 2.6
Reader Comments | Submit a comment »
Legal
This example program (this "program") was developed by a National Instruments ("NI") Applications Engineer. Although technical support of this program may be made available by National Instruments, this program may not be completely tested and verified, and NI does not guarantee its quality in any way or that NI will continue to support this program with each new revision of related products and drivers. THIS EXAMPLE PROGRAM IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND AND SUBJECT TO CERTAIN RESTRICTIONS AS MORE SPECIFICALLY SET FORTH IN NI.COM'S TERMS OF USE (http://ni.com/legal/termsofuse/unitedstates/us/).