Custom Cable Signal Connections with a Digital Camera and Digital IMAQ Board
Hardware: Image Acquisition (IMAQ)>>Digital Image Devices>>PCI-1422
Problem: I am trying to create a custom cable to connect my digital camera to my National Instruments 1422 or 1424 frame grabber. However, I am not sure how to connect the data signals. Which data line on the frame grabber is the most significant bit (MSB) and which data line is the least significant bit (LSB)? Also, how should I connect my Line Enable (Horizontal Sync or HSync) and Frame Enable (Vertical Sync or VSync) signals?
Solution: The answer to both of these questions can be found in the camera file. Each digital camera must have an associated camera file, specified by camera manufacturer and model number. For more information on camera files, please refer to the
Digital Camera Basics Tutorial, linked below.
Here is how you can interpret the information in your camera file to answer the above questions.
- Which Data Line is the LSB/MSB?
In the camera file, the Look Up Table (LUT) transform maps the data lines from the camera to the data inputs of the board. The LUT specifies which data lines on the board correspond to the MSB and the LSB from the camera. If you are building your own cable, the LUTTransform line of the camera file will tell you the orientation of the bits. In most cases, the transform will use the following default configuration:
LUTTransform (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
which maps the LSB of the camera to Data 0 on the 1422/24 boards, and the MSB to Data N-1 (for an N-bit camera). The indices in the transform refer to the bits from the camera (first position is LSB, last position is MSB). The numbers for each index refer to which data line of the board we have cabled to that particular bit.
- How Do I Connect the HSync and VSync Lines?
HSync is also referred to as the H Enable (or Line Enable). VSync is also referred to as the V Enable (or Frame Enable). For more information on these terms, please refer to the Digital Camera Basics Tutorial.
There are many modes available, but only two are commonly used (for area scan and line scan cameras). The three configurations below cover almost every camera you should see. The user manual for your digital IMAQ board shows that there are four different enable connections including Enable A, Enable B, Enable C and Enable D. Please refer to the Signal Connections section of the User Manual for information on the pinout of your IMAQ board (linked below).
- Area scan with frame enable connected to Enable A and line enable connected to Enable B:
Enables {
Mode (0x2)
HEnable (0x0)
VEnable (0x0)
}
- Area scan with enable connections reversed:
Enables {
Mode (0x2)
HEnable (0x1)
VEnable (0x1)
}
- Line scan with line enable connected to Enable A and no frame enable signal:
Enables {
Mode (0x0)
HEnable (0x1)
VEnable (0x3)
}
Related Links: Developer Zone Tutorial: Digital Camera Basics Product Manual: IMAQ PCI/PXI-1422 User Manual Product Manual: IMAQ PCI-1424 User Manual Knowledge Base 2CE7SIYJ: What are the Timing Diagram Requirements for the IMAQ 1424 and 1422?
Attachments:
Report Date: 01/02/2004
Last Updated: 11/06/2007
Document ID: 351ASKOK
