Francois Ouellette

Fausto, That was indeed the problem. Everything working fine now. Thanks!

Thanks, I'll look into it.

Hello! I am generating a sine wave with the USB-1808X (10 Hz, 2V amplitude), and measuring it using one of the 8 input channels, by directly connecting output and input. In the future, the input will come from another source (photodetector). I made a Labview VI to handle both tasks, on a desktop computer. However, the sine wave I measure has a strong dc bias on it, about 11 or 12 V, which actually increases or decreases slowly with time. In the end, I can only see it if I put a strong negative bias on it (-7 or -8V), otherwise it's outside the -10 to +10V measurement range. BUT, if I use exactly the same software on my laptop, it works perfectly fine. No bias. I just measure exactly what I generate. Only the computer is different. I've checked everything, cables, USB cable, different USB ports. If I measure with a scope, there is also no bias. I tried different inputs, same thing, although I also noticed a small, and changing bias on the other empty input ports. What's going on????

Hi @Jeffrey, I did just that, works like a charm! Thanks for your help!

Hello all, I'm using the USB 1808x to generate a modulation signal to a laser (5 kHz square wave), and detecting a reflected signal from sensors, which are then analyzed. I need very good synchronization between the output and the input, because the measurement depends on the shape of the reflected signal. I'm now sampling both output and inputs at 200 kHz, but require synchronization to be better than, say, 100 ns between the two. Right now, I use the LabView vi's to generate two tasks: one for output and one for input, as it seems I cannot generate a single task doing both. I've merged together the two examples VI's for continuous generation and continuous acquisition. The whole thing works well, except that there is always an arbitrary delay between the two that changes whenever I start the program, which is not just an integer number of samples, but can be a fraction too. It's really not clear (to me, anyway) what is the best way to synchronize the two. Should I use an external trigger or external clock? If so, how to use it within the available vi's? I will post details of my vi structure later if necessary. Thanks for your help!

Hello, I need to chose the best board for my application. I have 4 signals to digitize simultaneously, at 5 kHz each, with at least 20 samples per modulation period. 12-bit resolution is enough. I also need to perform a simple operation on the data (difference between two samples in one cycle divided by their sum), and average the results once per second (ideally all 5000 cycles), so I get 4 averaged measurements per second (1 per channel). So either I need throughput of 400kS/s to the computer (and perform the calculation on the data), or, if it is at all possible, perform the calculation on the board itself (by programming the FPGA)? I normally use Labview for the computations and the user interface. I have used a RedPitaya board so far, which is overkill in terms of speed and resolution, but also the throughput to the computer using LabView is very small, so I can only average about 4 modulation cycles per second, and there are only 2 input channels. So I am looking for a better option to build a working prototype. It seems to me that the USB-1208HS could do the job, but I am not sure. Can you help? Thanks in advance!