Need Guidance in NI-6363X BNC and Screw Terminals

[Hasham622x]

Hi,

I am using the NI-6363 DAQ system to capture data from multiple analog input channels configured in RSE mode with finite sample, with an external trigger on APFI0 and a re-triggerable approach. However, I am encountering limitations with the On-Board Sample Clock frequency:

• For a single channel, I can achieve a maximum sampling rate of 2 MHz/sec.
• For two channels, the maximum sampling rate drops to 1.0 MHz/sec.
• For six channels, the maximum rate is 360 kHz/sec.
• For 16 channels, the maximum is 130 kHz/sec.
• For 32 channels, the maximum is 65 kHz/sec.

I attempted to set a sampling rate of 1.0 MHz/sec for 16 and 32 channels, but I encountered an error indicating the need to increase the ADC conversion period.

Additionally, I noticed transient behavior in the initial captured points for individual channels, which affects the consistency of the data.

Could you please guide me on how to achieve a sampling rate of 1.0 MHz/sec for 16 and 32 channels (RSE mode)? Furthermore, any suggestions to address the transient behavior observed in the initial points of each channel would be greatly appreciated. Thank you!

[GerdW]

Hi Hasham,

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@Hasham622x wrote:

I am using the NI-6363 DAQ system

Could you please guide me on how to achieve a sampling rate of 1.0 MHz/sec for 16 and 32 channels (RSE mode)?

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Please read the datasheet for your DAQ device!

It clearly says "multichannel max (aggregate) of 1MS/s": this is what you bought and it is what you got!

There is NO WAY to read 1MS/s/channel for 16 channels with this mux'ed DAQ device…

[NIquist]

As GerdW said, the card you have is a multiplexing DAQ, so you are sharing the same ADC for every channel.  Every time you double the channels, you halve your sample rate. 😖  You need to buy a simultaneous sampling card to maintain sampling speed with multiple channels.

Additionally, multiplexed channels need even more time to settle, especially if they go from a large signal to a small signal.  The Programmable Gain Instrument Amplifier (PGIA) may have to switch gain to accommodate the change and require even more time.  You can also add extra grounded channels between active channels to get the best signal increasing the sampling time needed even more.

You can learn about all this stuff here:

 Getting Started with NI-DAQmx - NI

Ignore the sections on the DAQ ASSistant.  You will learn much more about working with DAQmx by using DAQmx. 😊

[santo_13]

You already got good explanations. You're at a point to realize the limitations of the hardware you have.

[Hasham622x]

Hi,

Thank you for your reply. Could you please guide me on the transient behavior of RAW data points in both single and multichannel approaches with an analog retriggerable signal at 360 Hz? In both approaches, I have set the maximum sampling frequency.

Kind regards

Hasham

[Hasham622x]

Hi,

Thank you for your response. If you don’t mind, I’d like to ask for your suggestions regarding a simultaneous multichannel AI card with independent external trigger (hardware trigger) capability.

Currently, I have been working with the NI-6255 USB, but I encountered time initialization delays when implementing a retriggerable approach. To address this, I switched to the NI-6363 (BNC and screw terminals), which resolved the initialization delay issue. However, I now realize that I also require simultaneous sampling functionality with a dedicated ADC for each channel to meet my application needs.

I would appreciate your guidance on a suitable card that fulfills these requirements.

Thank you for your assistance.

Kind regards

Hasham