Ethernet CompactDAQ throughput

[mkovacic]

I have to accomplish distributed measurement of multiple signals over Ethernet. The number of signals is quiet large so I have to verify if the proposed measurement system will be able to acquire all signals. The signals that have to be measured are divided in fast and slow signals. Fast signals have to be sampled with at least 10kHz and slow signals (temperatures) with 1Hz. The number of fast signals is 32 while number of slow is 16. The hardware I planned to use is:

cDAQ-9188 Ethernet CompactDAQ chassis

3x NI 9205 32-Channel 250kS/s Analog input modules

first 16 of fast signals will be measured with first NI9205 module set to sampling frequency 250kS/S/16

other 16 of fast signals will be measured with second NI9205 module set to sampling frequency 250kS/S/16

slow signals will be measured with third NI9205 set to low sampling frequency.

It is crucial that all fast signals are sampled synchronously. Can cDAQ sample signals from two NI9205 modules simultaneously or it has to sample one block from one NI9205 module and on other afterwards?

Best Regards

Marinko Kovacic

[Brad_K]

Hi Marinko,

The NI-DAQmx Help file has an explanation of this under NI-DAQmx Key Concepts >> Timing and Triggering >> Timing, Hardware Versus Software >> Multiplexed Versus Simultaneous Sampling:

In other words, the NI 9205s convert data at the same time, but each NI 9205 converts only one channel at a time (not simultaneously).

Brad