Dear Sir,

We are facing he following problems in DT80 (being used in Automatic Weather Monitoring Station for acquiring weather information from various sensors)

1. DT80 is acquiring erroneous data from some of the sensors randomly.It acquires underrange or overrange data fro Temperature and wind direction sensors (resistance),Relative humidity and solar radiation sensors (voltage) etc. This incident may take place once/twice in 30 minutes or in 2 days or in 7 days.
2. Sometime the DT80 health test shows dataTaker Health-FAIL(some of the parameter fails and sometimes no parameter fails) but after sometime (say 1-15 minutes )the dataTaker Health becomes PASS. Most of the times during this phase the results are erratic.
3. DT80 status checks fails when we are selecting USB memory space more that 50 MB and the system hangs for more that 400 MB USB memory space selection selection. We are badly in need of your expert advice.

Regards,
Pradipta Ghosh

Sounds like current loops and/or poor grounding causing the analog inputs to go outside the common mode range. Maybe disconnect all of the sensors and add them back one by one until you see the problem.

Are you logging directly to the USB drive? I wouldn't do that as you can't guarantee the performance or even if the drive is always inserted properly. If the connection to the flash drive is intermittent you could get all sorts of strange errors and performance.

My rule is to use the USB drive for transferring data and files only. I always log to the internal card, if I need more memory I swap the internal CF card for a larger one.

Dear Sir,

This is to inform you that I used the internal memory for data logging and copy the logged data to USB memory and there is no more underrange and/or overrange errors.

Thanks.
Pradipta

Dear Sir,

In my earlier reply I mentioned that results are OK but unfortunately I am getting similar errors again after a few days without pen drive (data storage on internal memory). I am facing this problem with wind direction and some other sensors . This is happening with another DT80 as well.

We are using similar sensors with DT50 and the results are perfect.We never had problems with the DT50.

When we are logging data on internal memory results are quite good and acceptable to customer (e.g. atmospheric pressure is 996 mbar ave without pen drive but this is 989 mbar with pen drive plugged in).

Please help,
Pradipta

Good morning Pradipta,

It looks like you have a ground loop problem. Please ensure the wiring is correct and that there is nothing connected to the A GND terminal on your DT80.

Cheers,
Roger