What should be the possible reason for fluctuation the voltage value in data logger 34970A?

[AnkitRamani]

Hello,

I am still not more familiar with Data logger function.

Here in attachment I have attached my VI in that I got some problem like when I run first time then its give 11 v something and when I run second time then its give value 3 volt means the voltage value is fluctuated every time.

Would you please tell me that what are the possible reasons for this type of fluctuations.

Thank you very much.

[Dennis_Knutson]

Is either of those readings what you expect? What happens when you set a breakpoint and single step through the code? What about when you set the instrument up manually? 

[AnkitRamani]

Thank you very much for reply.

I expect voltage below the 2v when datalogger and instrument both are connected.

And sorry for your remaining two questions because I have no idea how to set a breakpoint and single step though the code, and can you please tell me that how can I set my instrument up manually.

attached diagram was given to me and asked to setup like that.

And I have read all the commands and instructions but still I have no clear idea about data logger.

Thank you very much once again.

[HendrikG]

Hi Ankit,

you can set a breakpoint according to the picture below by rightclicking on a wire.

Then execute your VI and will stop when it reaches the breakpoint.

Afterwards you can use the 3 buttons marked below to continue step by step,

LabView pauses the execution everytime it reaches the next breakpoint or a SubVI.

Use the first button to step into every SubVI you come across to debug your VI in detail.

If you reach a SubVI known to be working correctly (like the Agilent driver VIs for example), use the second button to step over the SubVI. LabView will execute the SubVI but stays in the current VI so you don't need to single step through the whole SubVI.

The third button finishes the whole VI without pausing at SubVIs, only breakpoints will pause the execution.

Another useful debugging feature are probes. You can also add them by rightclicking on a wire.

You can add several probes in your VI and use the Probe Watch Window to see

which values are passing through the wires.

Try to combine breakpoints and probes to debug your VI.

Let me know if it helps!

I'll also have a look at your VI, but it's difficult for me to debug because I don't have the Agilent 34970A.

Can you give a short description of what you are planning to do with your VI?

Best Regards,

Hendrik

[RTSLVU]

I see you are using the 34970A EZ-Voltage VI, you should avoid that.

I have been using the 34970A for years and have noticed the units produced in the last few years are not as well made. You need to use the advanced configuration VI's and setup some integration. Either 2-10 PLC (Power Line Cycles) or Apature (set your own integration time like 200mS).

This does make your program more complex as you need to take several steps.

Configure the communications

Configure your channels for measurement type

Configure and buld a scan list

Scan the channels each time you need a reading.

I attached some screen shots of a program I wrote as an example.

I also attached my "Scan Agilent Now" vi that I use all the time since this part never changes

I see I only get three attachments so I will attach the Scan Now vi to another post.

[RTSLVU]

Here is my agilent scan vi

Also using the 34970A this way instead of the EZ-Vi's give you the ability to use the monitor (Press the MON button) to see what the voltages are on the instrument display. Maybe your voltage is fluctuating.

[AnkitRamani]

Thank you very much for your help.

As per Hendrik suggestion I tried to set breakpoint and then I execute my vi but I don't have any effect means everything is going smooth and still I have fluctuations in voltage.

My task is to measure the reading from the DO2 slot when DO2 is connected with device and Datalogger switch is ON then I have voltage something less then 2 volts and is similar as I have attached one screen shots in previous post with table of measurements.

The Thing is before some days everything was working correctly but from last 3 to 4 days I got this type of problem, when ever I measure the voltage value across DO2 everytime I got some different values some time its seems 3v, some time its 11 volts, some time its 0.23 v.

So I am very much confused.

[AnkitRamani]

As per attached vi Of RTSLVU I have monitored my channel and every time I got fluctuation in voltage values.

So will you please tell me that what kind of changes I have to do in order to avoid this type of fluctuations.

Is there any settings I have to do in Datalogger instruments, becuase I am not much familier with this instrument and my testing system is totaly depend on agilent data logger so I am little bit scared to do any experiments on Datalogger.

Thank you verymuch again for your help.

[RTSLVU]

---

@AnkitRamani wrote:

As per attached vi Of RTSLVU I have monitored my channel and every time I got fluctuation in voltage values.

So will you please tell me that what kind of changes I have to do in order to avoid this type of fluctuations.

Is there any settings I have to do in Datalogger instruments, becuase I am not much familier with this instrument and my testing system is totaly depend on agilent data logger so I am little bit scared to do any experiments on Datalogger.

Thank you verymuch again for your help.

---

Have you measured the voltage with another meter or looked at it with an oscilloscope?

Because it sounds like your voltage may actually be fluctuating.

You did not mention what card you are using in the 34970A,

I am guessing you are using a 34901A multiplexer since that is the most common, but a 34908A is also a multiplexer and there is one important difference between the two cards.

[AnkitRamani]

Thank you for your reply..

Yes may be you are right I have to check my device may be there is possibilities of fluctuations in voltage occurred from device it self.

And as a multiplexer I am using 34901A, and 34903A for a switching/relay.

Thank you very much once again for suggestions...