cchiarello

Fausto, Thanks again for your support. I have spoken to my supervisor and the magnitude of the error we are observing with the current setup (+- 2 bar) seems to be acceptable. The transducer giving +- 0.5 bar was not connected to the system, and I suspect that is why it had such a good accuracy. We were able to achieve better results using a USB-1208L, but again, the current setup seems to be working just fine. I will let you know if any further support is needed! Thank you, Conrado

Hi Fausto, Once again, thanks for the response. We are using a PX613-5KG5V (0-5000 psi). If I'm following the calculations correctly, that would imply 1 mV = 0.086 bar, which, in turn, would give 0.21 bar/LSB. This is in the same order of magnitude of our noise, but still lower than what we measure. Do you have any suggestions on how to minimize the fluctuations (aside from buying a new board?) Thanks, Conrado

Hi Fausto, Thanks for the quick response. We are using a PX-613 by Omega (https://assets.omega.com/manuals/test-and-measurement-equipment/pressure/pressure-transducers/M947.pdf) We are using a standard desktop PC. We are further investigating the issue. We have replaced the power supply with a 24V grounded, more stable one. It reduced the noise considerably, but we are still a bit short from what we would expect (+- 0.5 bar). Grounding V- does not seem to make a difference. We are connecting V+ (red) from the sensor to V+ in the power supply; S+ (green) from the sensor to V+ in the board; and V- from sensor is connected both to V- in the power supply and the board. Is that the limiting resolution for this model in our application case? Thanks, Conrado

Hello. We are using a USB-1208LS acquisition board to measure the signal of a pressure transducer. The signal, however, is far from being smooth (accuracy is +- 5 bar). We are measuring it using differential setup and a 24V power supply to the pressure transducer. We have tried different ports, supplying 12V to the transducer, different transmitters, and different sensors. All of the setups exhibit the same noisy behavior. When grounding common (V-), the voltage between signal (V+) and GND becomes a constant 1.415V, as does the voltage between V+ and V-. If ungrounded, the noisy signal is recovered, but the voltage between V+ and GND stays at 1.415V. We have used the same board model before and the results were always outstanding, as it is with different models (USB-TEMP-AI). When replicating the setup, however, we are not able to have the same high standard measurements. Would you help us smoothen the signal and troubleshoot the GND port voltage? Thanks, Conrado