framegrabber

[dorkxer]

Hi, I have a NI 1427 Camera Link Capture card that is collecting data from a Dalsa Piranha 2 line scan camera. Using the C based NI code, I can successfully capture data from the camera/card. However, my problem occurs when I attempt to capture the End-of-line sequence that the camera can generate as a test. I am unable to capture this data.

I have verified with the camera manufacture that the camera I have can actually produce the 14 bits of test data and that this test data is appended to the end of a valid image. What I am unsure of is how to force the NI 1427 card to capture image data afte the line valid signal has gone low. It is high during the acquisition of the normal image. Does the 1427 board support his feature? Do any of the NI framegrabbers support this feature?

Thanks,

[Daniel_H1]

Hi dorkxer,

I belive the end of line sequence will be transmitted over the serial lines, so you'll need to make sure your camera file includes the serial command to enable the end of line sequence. According to section 3.17 of the user manual, you will need to send the serial command "els" to activate the end of line sequence. Which camera file are you using? Can you please attach it here?

Regards,

Daniel H.

[Daniel_W]

The PCIe-1427 doesn't capture any data when Line Valid is low.  I'm not aware of any NI framegrabbers that support this feature, but it's a novel use case.  Can you tell me why this end-of-line test pattern is important to you?

[dorkxer]

Thanks for the replies.

To answer the first reply of Daniel H: I have activated the end-of-line testing both by modifying the camera file and by sending the serial write commands within C to the camera. I have verified that the end-of-line sequence has been enabled by sending and capturing the "gcp" command (I belive that is the correct command, it prints all the current parameters of the camera).

To answer the reply of Daniel W: I am beginning to see where collecting data after the Line Valid signal is a novel use case. The reasoning behind us wanting to capture this data is that it contains rolling counters. Recording those counters will allow us to verify that we are not dropping any lines within our acquisition.

[Daniel_W]

Hello dorkxer,

That sounds like a useful application.  I'll make sure that it comes up in our next round of feature request considerations for Camera Link framegrabbers.

In the meantime, since the PCIe-1427 can't record this rolling counter when LVAL is low, I can at least offer the following:

* The minimum LVAL low time between lines for the PCIe-1427 is one clock cycle, so it won't lose lines for that reason.

* The time for the PCIe-1427 to rearm itselve between frames is less than 20 pixel clock cycles, so if the camera's LVAL low time is greater than 20 clocks (this is true for the vast majority of cameras), then you won't lose lines between frames, either.

* Ensure that you have enough acquisition buffers for your processing never to fall behind your acquisition

In the past, I have seen customers measure the frame rate (hence the line rate) of acquisition, and use that information to determine if any lines have been dropped.

In VHA linescan acquisitions, the Lost Frames property node can also report if any frame pulses (from a DIO line) have been missed.

Thanks for your feedback.

Regards,

Daniel Wilding

Staff Digital Hardware Engineer

National Instruments