Hi,
I have cDAQ-9184 chassis with two modules installed: NI 9215 (AI) and NI 9263 (AO).
AO generates 5kHz signal and AI acquires it. In the beginning everything is fine, but after 20-30 seconds it has delays (up to 30 seconds!) between generation and acquisition.
Time lag depends on DAC rate. If it 20*5000=100kHz, delay=15sec, if it 10*5000=50kHz the delay is 30sec.
It works with PCI-DAQ version, but i can't understand why it has such delays with ethernet chassis.
I tested it on gigabit ethernet with directly connected chassis to host. But i don't think problem is in network, cause net load is about 0,55% and ~ 1Mb\s data transfer. CPU load is also low.
And i think trouble is in generation, not acquisition, because it flushes all samples in read buffer ("availsamplesperchan" is near number per channel in DAQmx read) and because changing DAC rates influence on signal updates.
Also, it works good without such big delays at lower signal rates, for example, 50Hz sine wave generating.
Example code is in attach. I'm reading 100 periods of 5khz-sine wave, 16 points per period (update rate=80kHz, 1600samples). And have 5khz sine generation of 100 periods with 20 points per period (rate is 100kHz, 2000samples).