Reverse current

[JB]

Your LEM may be damaged ?

What is its output voltage without any current ? It must be near to 2.5V.

How do you measure the output level ? Is the voltage measured by a voltmeter identical to this by your code ?

Are you sure your amperemeter measures correctly ?

Do you use a global channel and a scale or a task  (defined with NI's Measurement And Automation Explorer) in your "top secret" code ?

[rolfk]

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@kdm7 wrote:

Hi Gerd,

I am reversing the terminals of the current supplier to see if my VI can measure negative current. By the way the lem sensor's range is + or - 19A.

This is a different problem, so I started a new thread.

Sorry, I cannot provide my VI, it is confidential.

---

How can a VI be confidential?? Did you sign an NDA with LEM that forbids you to show your test code with which you try to read their sensor? Nobody asks you to post your fully fledged super duper top secret application here.

But if you have a problem with some equipment, rather then trying to debug that within said super duper application it is always a good idea to create a small test application instead were you can concentrate on the problem at hand without having to deal with 500 other hardware modules and initializations and what else. This little test application is what anyone would need to see to be able to understand what you are actually trying to do and why it might not work the way you think it should.

You can of course try to get help by just trying to explain your problem in many thousend words. But as has been proven over and over again, most people are not able to know what others might need to understand what they are doing and more often than not it is in fact impossible to tell everything that could be relevant in some prosa text. You only make your life harder and decrease the likelyhood that those who might be able to help you will actually bother to do so.

[kdm7]

Got it.

The problem was with the sensor. 

I understand. I will provide vi next time.

Can anyone tell the hardware connections for differential mode. I tried connecting "out" to A0+ and "0v" (of the sensor) to A0- .(which might be wrong as I am not getting the output at MAX itself) I am using lem ctsr 0.6-p, similar to my previous sensor. 

Here is the specs of the sensor http://www.lem.com/docs/products/ctsr%20series.pdf

[GerdW]

Hi kdm,

what's the use of differential mode here? What kind of "better" results do you expect here?

You need to connect (LEM <=> USB6008):

Uc <=> +5V

GND <=> GND/COM

Vout <=> A0 (not in differential mode) or Vout <=> A0+ (in differential mode with A0- = GND)

[kdm7]

Hi Gerd

I don't know about the results. Just want to experiment with differential mode.

Do you mean.. 

(in differential mode)

Uc <=> +5V

GND <=> GND/COM

Vout <=>  A0+ and A0- = GND/COM

[GerdW]

Yes.

[JB]

See here and follow the instructions. They will show you how to configure the measurement and connect the sensor.

Read also the "Analog Input" chapter in the user manual (from page 11) of the NI USB-6008.

[kdm7]

Hi, 

When I use a solar panel (with a +ve and -ve terminal), I connect as follows,

(For differential measurements)

+ve  to  AI 0+

-ve to AI 0-

and AI 0- to GND/COM.  Am I right?

And also for differential measures, the limit is + or - 10V. But my channel reads a maximum of +5.22723V. I have not put any limitations in the program too. What could be the reason for this behaviour?

[GerdW]

Hi kdm,

 Am I right?

I don't think so. Why do you want to connect -ve with GND?

And also for differential measures, the limit is + or - 10V.

No. Read the manual of your USB6008!

What could be the reason for this behaviour?

Your wiring? Your programming? Who knows?

[kdm7]

Got it.

+ve to AI 0+

-ve to AI 0- 

And limit is + or - 20V.

Had got my wiring wrong.