NI 9205 AI drop

[StevenD]

Hello,

I have a project I am working on that includes a cDAQ and 3 modules. One of the modules is a NI 9205 analog input card. With it we are reading 7 trandcucers. The first channel always seems to read correctly, but the others will read correctly then drop off in voltage. We are wired up on all channels for differential inputs, some channels will hold for minutes with no problem some will seem to drop off within a few seconds. I created a task in MAX to watch the channels and have attached a video of said behavior and a screen shot of how the channels are configured in MAX. Any insight into why this is happening?

Watch voltage 10

NI 9205 Analog read error

[Henrik_Volkers]

Wow, a >2.5Meg picture for a screen shot.

Ever tried to hit Alt-Print and saved the clipboard as a PNG?

What type of transducers and how are they wired, supplied?

Sorry not bandwidth to look at your video....

[StevenD]

One of the transducers is a Honeywell TJE, the other 6 are Omega PX01 transducers. Both are wired with 24 vdc excitation and differential for the signal. We have tried disconnecting the cable at the transducer side and connecting a 4.5 volt battery with the same problem. The NI9205 will read the 4.5 vdc for a few seconds, then it will drop down to 3.1. 

[Henrik_Volkers]

can you provide a schematic of the connections incl. grounding/shielding? 

Sounds a bit like something is running into saturation, out of common range.     Bias currents .....