06-11-2012 03:19 PM
I am running a fairly large worksheet that needs to interact with PCIboads from measurement Computing at a very high speed in order to interact with my machine. One of these boards is a Data Acquisition board, and the other is a Digital Input Output board, controlling switches.
The program only seems to run smoothly when I have the sampling rate very low (2 Hz's). I need to be running at a much higher sampling rate . I understand that the faster my sampling rate the slower it displays, but by checking the files that I am writing to, I can see that it is not actually gathering data at this speed. I am using a brand new fast computer so processing power should not be a problem.
Is this a problem with dasylab itself? My program?
I have attached my program below.
06-11-2012 03:32 PM
The two boards are:
PCI-DAS6033 from measurement computing
PCIe-DIO96H from measurement computing
the PCI-DIO96H board connects to a CIO-ERB48 relay board (below)
06-11-2012 04:13 PM
Here's the bad news -- I don't have that hardware combination here, so I cannot reproduce it.
I do know that the A/D card is hardware timed, and the timing is well defined by the clock on the device.
The DIO card is software paced, which means that the program (DASYLab and its driver) are using a PC timing source. The highest possible update rate is determined by a lot of factors, including the computer and the whims of the guy who wrote the driver
And you have a relay board which is relatively slow. That may determine the maximum output rate.
So, if the input channels are connected to the output channels, you need to reduce the output rate to the Digital Outputs. Does that make sense?
You can sample the Analog inputs at a high rate, and then use an average or a separate module to reduce the sample rate before it gets to the Digital Output module. All channels connected to the output need to use the same rate. You're using the "Driver", and can leave that at the lower rate when you increase the Dev1-AI HW rate.
If you need more help with these devices, and to determine the highest possible sample rate for the PCIe-DIO96H, you need to contact Measurement Computing directly. Call 508-946-5100 or go to www.mccdaq.com. They are staffed from 8 AM to 6 PM, EDT.
06-11-2012 06:08 PM
The max sampling rate for the DIO96H board seems to be 33.33 Hz and weirdly enough the program runs fairly smoothly at this speed. However, when I try and run at speeds in between that (say 20 Hz) the program seems to freeze/lag and not disply the inputs at the correct speed. I have all of the boards set to the lower sampling rate, so the interaction should be fine. Do you have an explaination for why some sampling rates work and others dont?