Offset nulling calibration vi

[KumarR]

Hi,

I am acquiring data from load cells (which are full bridge circuits). I am using LabView 8.6 and SCXI 1520 with 1314 terminal box. Previously I used to first read the nulling voltages (at no-load condition) first and then acquire the voltages at loaded condition. Net voltages would be the voltage at loaded condition minus the nulling voltages. But I thought if I use DAQmx Bridge Offset Nulling Calibration Vi instead, I get better results. But I have a problem with this.

I am attaching the code. When I start the program first it nulls the offset and then it enters the while loop.

My problem is that Offset nulling part before it enters the while loop takes a very long time.

Would you please tell me why it is taking so long? Is there a way to make it fast?

Thanks

Rajeev

[Broken_Arrow]

I can't open your code at the moment, but do be aware that the VI is adjusting the potentiometers on the card (coarse and fine) and this simply takes a while. On the system I work with, it seems to take 1 or 2 minutes. Is this the "very long time" you are referring to? If yours is taking appreciably longer, be sure the load cell is mechanically stable (unloaded or not) during null time, and the electronics are quiet with a stable excitation.

[KumarR]

Hi,

Thanks for the reply. The reason why you are not able to open the sent vi mgiht be that is looking for another vi it is using. I am attaching that vi below. In my case also it takes about 1 minute or little more. I don't know whether that is normal or I am doing some programming mistake. I would appreciate if you have a look at my program.

Thanks.

[Broken_Arrow]

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@KumarR wrote:

Hi,

Thanks for the reply. The reason why you are not able to open the sent vi mgiht be that is looking for another vi it is using. I am attaching that vi below. In my case also it takes about 1 minute or little more. I don't know whether that is normal or I am doing some programming mistake. I would appreciate if you have a look at my program.

Thanks.

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I don't think it is your program. The calibration just takes that long.

[KumarR]

Broken Arrow,

Thanks a lot. I think that is normal. I appreciate your help.

Thanks