WalterC

There are actually just two sensors now. These are proprietary sensors so I cannot supply a data sheet for them. They are externally powered and each one has its own power supply. The power is supplied from separate batteries.

We are picking up noise originating from the laptop that we use to connect to the USB1408FS and need suggestions for methods or devices to isolate the USB1408FS USB connection so that the noise is not transferred from the laptops. We have tried this with another laptop and the noise is lower but still present. And we've tried a different USB cable. We are using the ones supplied with the USB1408FS. Interestingly, the noise becomes greater when the barrel plug is inserted into the laptop from the power supply cable whether the power supply cable is plugged into the 120VAC source or not. But even when not plugged in, we are getting noise. There are some USB isolators on the market but I am not sure if they will work. They also want to know USB characteristics I am not very fam iliar with like data speed. So any additional information about USB1408FS requirements - particularly USB version and current requirements - will be appreciated too. Ideas needed, please.

So, the noise on this sensor signal is terrible when the laptop is plugged into its power supply that's plugged into the AC mains. By plugged into its power supply, I mean the 2.1mm barrel plug is plugged into the side of the laptop. It doesn't matter if the supply is plugged into the AC mains. That is causing some of the problem and I found another problem in one of our other modules that I fixed and that addressed much of the drift. However, we still have some. Everything is still in single-ended mode. This sensor is being read on ACH0. ACH1 is active but nothing is connected to it. I have read that when they are active there can be some crosstalk as they are multiplexed in. So, I have connected ACH1 to ground on the USB1408FS and will test that. I've seen the unconnected analog channels float up to 1.4 before so it would make sense that if the adjacent channel is active and floating that ACH0 could be impacted. Although I would assume that since ACH1 comes after ACH0, it might not. But maybe I don't understand how crosstalk works in this situation. Any thoughts will be appreciated.

We are using a USB-1408FS to measure three signals in single-ended mode. These signals are connected to pin 1, pin 4 and pin 5 and we are using pins 3 and 6 for ground connections. We have been using this successfully in one lab on a test platform and have moved to another lab an have it connected to a prototype of the same system we were using in the lab. The analog signals have a range of 0 - 1.8V. We have three laptops that we can use - Asus, HP and Lenovo. When we start the DAQami software collected the analog signals, channel 0 (pin 1) is tuned where it should be - ~0mv, sometimes a bit negative. Before anything in our system changes to cause the sensor signal to change, we observe a relatively slow rise in the baseline on channel 0 to between 300 and 400 mv. At one time we could force this behavior by unplugging the Asus laptop from its AC adaptor at the barrel connector on the laptop. We no longer had the rise occurring for about a day but ITS BACK! :) Are we doing something wrong with the USB-1408FS? We are just using it to capture signals for analysis. But, this is effecting the control system.

Thanks! Just FYI, we borrowed a unit from a friend's lab, and we're seeing the same behaviour on those open lines on them. The signal comes in from the output of a unity gain buffer op amp circuit. When that line is measured with a DVM, it's 0.497 V. But when connected to the input on the USB-1408FS, the DAQami software reads 1.4V.

We've been using the USB1408FS in single-ended input mode for some time now with no issues and then yesterday we blew a microcontroller. Replaced it and then blew another one and never suspected the USB1408FS but when we measured the open voltage on channels 02, 03 and 04, they all had roughly 1.4VDC on them. None of the other channels have this. They are all at zero with nothing connected. Any ideas what might be going on with the device?

Hello, I'm using DAQami (see screenshot) and it and the USB-1408FS are meeting our needs so very well! It would be really be useful when we save data captures to be able to add some notes about the test run that would accompany the files that are saved. Is this possible? I haven't found it in help so right now I am having to notation things in a separate file with a reference to the file name DAQami saves. If this isn't presently available, could you add it to a wish list for future development please?