Foreshadow

I tried with 2 while loops with each one having the loop content but without the sequence structure but it was horrible, there was a stop of reading from a CAN every now and then, so much data was lost. The reason why the while loop is at 2.5ms, is because we rely on the TickCounter of the RT Controller in order to get results of tests or to execute tests. I know we can use the difference of timing of the CAN timing vs the TickCount, but for some reason the project manager doesn't seem trust the timing of the Canbus as we do not know when the CAN timing is executed on the unit I tried with Queues on my simulation (I created a Windows VI to simulate canbus data when I was unable to work on the testers with the unit and RT controller), but it took too more time to execute the Queues than the timing of the loop (was confirmed when using the profile tool). Unless the Queues are executed differently on the RT than on a Windows machine then i'll try it. I based my simulation with the NI Example Queue basics.vi (find example/Optimizing Applications/Syncho Task). I'll try it on the RT Controller. With a 2.5ms loop, it reads the 16 CAN frames, so the array is usually 15-17 CAN frames long. What would be the best ratio between the loop from the RT Target and the loop from the Host PC ? I think i'll also optimize the CReadMult to do all the operations of it on the Host PC. Oh and the timed loop is necessary as it runs on a RT Controller. Thanks. QUOTE (Ton @ Nov 14 2008, 12:32 PM)

I have been on this problem for a few weeks now and still unable to fix the problem: Description of the problem: 1- When reading from 2 CAN channels with a Real-Time PXI Controller, the Processor runs between 70% and 80% (but most often at 80%). (Nothing else runs on the RT, but it will be required that more vis to run on it in the futur.) When running the vi on the Host PC, the processor on the RT controller tops at 100%. Some Data loss occurs. 2- Minor problem: Board doesn't always reset even with 2 resets.) Program Content (view attachement for more details): 1- While Loop at 2500us containing a sequence structure to read 2 Canbus ports in sequence. To read the CAN, I use a ncGetAttr (Read Entries Pending) followed with a ncReadNetMult.v. Data is then unbundled and set into an array in order to use a shared variable (using Real-Time FIFO). This alone takes 80% of the CPU LOAD. 2- First sequence: Canbus Reset.vi. Second Sequence has the Config (set at 1MHz), Open then CActions of Reset and Start. Description of Task: Read 2 CAN channels from a UUT on a Real-Time PXI Controller (8196). 16 CAN frames per whole CAN Message per channel. The 16 CAN frames are sent in 2.5ms. The Host PC that reads the data from the Real-Time Controller at any rate (I usually set it at 4 times the loop time of the RT Target). FIFO Configuration: 12 elements of the CAN frame + RT TickCounter. As 64bits Double or 64 bits U64. 13 elements per array. 512 Arrays (this number varied alot). The lower the # of arrays, the more random data loss occurs, but the higher it is, the more the duration of data loss is long. Note that sometimes i get the last frame and appears in the log as many times as loop size. Host PC: Reads the Shared Variable in a For Loop with the #the same as the FIFO size (or higher). Note: Many Disable diagrams, but doesn't affect the program in any way. Its other tests done. Thank you