08-19-2024 04:31 PM - edited 08-19-2024 04:40 PM
In the example project NI 9227 Getting Started.lvproj, the example shows how to read a buffer of single point values from all 4 channels. For the host VI, the dt is calculated from parsing the string enumerator and multiplying by 1000 to get the samples per second. The text "2.00 kS/s (NI 9227)" should parse then to 2000 which gives us a dt of 1/2000 or 0.0005.
However the documentation shows that the enumerator is per channel, not all 4.
This leaves me with 2 questions:
The NI Example project can be found under "Hardware Input and Output \ CompactRIO \ Module Specific IO \ Analog Input \NI 9227 Getting Started.lvproj "
Solved! Go to Solution.
08-19-2024 07:49 PM
The shipping example is correct.
When reading back from the FIFO, the host is always returning data in a multiple of 4.
08-20-2024 02:25 PM
But that is exactly my point!
1. The FPGA reads the 4 channels, and then writes them to the FIFO Block in loop.
2. For the waveform, every dt value for AI0 should be 1/(2000*4) since it has to read the other 3 channels before can it get back to AI0!
08-20-2024 03:08 PM
@eli.barber wrote:
But that is exactly my point!
2. For the waveform, every dt value for AI0 should be 1/(2000*4) since it has to read the other 3 channels before can it get back to AI0!
The channels are read simultaneously; each channel has its own ADC. Not sure I understand your question.
08-21-2024 12:29 PM
Thank you,
What threw me off was that I also have and RTD card (NI-9217) and an AI card (NI-9209). All three cards use the same language in the documentation of giving the conversion time/sample rate Per channel. And both of these cards are sequential in timing (At least that is what I have tested them to be).
But like you said, the current card simultaneously. This does seem to be the case when running it.
08-21-2024 04:13 PM
You can use LabVIEW to access most, if not all, of your device's properties if you are unsure in the future and don't want to hunt for a manual. See the snippet below for your case.
08-22-2024 03:23 AM
Hi eli,
@eli.barber wrote:
What threw me off was that I also have and RTD card (NI-9217) and an AI card (NI-9209). All three cards use the same language in the documentation of giving the conversion time/sample rate Per channel. And both of these cards are sequential in timing (At least that is what I have tested them to be).
So the documents provided by NI clearly describe the behaviour of your hardware!