Enki

QUOTE(Neville D @ Nov 7 2007, 01:32 PM) Thanks, I don't actually need to read anything but the one voltage channel on the AIO-600 at 500 Hz, I checked the Comm VI to verify that I didn't upload an older version and the second read loop is actually running at 50ms with only the one voltage in the loop by itself being read at 2ms. I've tried skimming out everything but the one loop with the Voltage read and the Communication loop, but still end up losing data somewhere. I've tried interweaving the read and communications using a timed sequence inside a while loop (currently discarding any data while it initiates a connection with the host), though not gotten any better results via that method either. neB, You may very well have a point about that spec being applied as a I/O device and not to the real time system itself. I've been talking to NI in Austin, TX as well to see if they know of anything. Though they seemed to think that my architecture was correct for the application and we did play with slightly slowing down the communications loop so it doesn't dominate the cFP processor, though after we tried a few things they decided they needed to do some independent research and that they would get back with me on a possible solution. Though I am starting to think that I may have just read the specs incorrectly and may just have to split out that particular channel and record it via another method and then weave the data back with the rest being read on the cFP.

QUOTE(Neville D @ Nov 6 2007, 05:48 PM) The hardware spec lists its update rate at 1.7kHz, maybe I've misread that into thinking its capable of the 500Hz sampling frequency. I've also changed the advise rate for the device to 1ms, previously I had it set at 2ms. I've played with reading in multiple samples and then transmitting them back in one block, but have actually gotten worse results from that than a straight pt by pt. Though I'm not fully sure how to implement that particular architecture.

Hi, I'm currently using a cFP-2120 module with a AIO-600 module that I'm attempting to sample a voltage at 500 Hz that I am then sending back to a Host PC via TCP communications loop. I've set up a timed loop with a RT FIFO to transfer the data between the sampling loop and communications loop. The Comm loop is a simple state machine type that flips between TCP read and TCP Write provided there is no error. There is another timed loop that runs at a lower priority that reads less speed intensive values and does some controlling, not too concerned about it finishing late as long as its not introducing too much jitter. Somewhere between my RT Target, which I've set up to use the 2120 LED's to indicate late loops and indicate empty FIFO buffers, and my host pc I'm losing sampling data. I should be able to/need to catch 500 points per second on this voltage channel. TCP communications programming is relatively new to me; so, I wouldn't be surprised if I'm losing data via TCP communications. I've included my VI's in anyone is interested though they are in a dev state and not streamlined for ease of reading or with proper documentation yet.