LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

Scaling Problems with USB 6000

Solved!
Go to solution

Hi,

 

i have a real big Problem with custom scale and a usb 6000.

i have different pressure sensors. one is 0-10v direct Output, three i´m measuring about a 500Ohm resistor.

The power source is 24V. Plus are connected to 0,1,2 and i took gnd from power source to the measurement device.

In DAQmax i see the correct voltage on every channel. But i´m not able to make a scale. I tested every Version (linear, table etc). I´m getting error -200077

What can this be? How can i create my Scale?

0 Kudos
Message 1 of 8
(1,697 Views)

Can you show the code you made?

-----

The best solution is the one you find it by yourself
0 Kudos
Message 2 of 8
(1,692 Views)

Hi,

 

of course.

 

scale-->error

without scale-->working

 

Voltagerange is ca. 1,95V-9,95V =  0-6bar

Download All
0 Kudos
Message 3 of 8
(1,682 Views)

Well, we don't know what you did (you failed to attach your VI).  But have you tried doing this in MAX first?  Open MAX, open Scales, and create your Scale (use the Help that MAX provides) -- be sure to Save (upper left corner of the right-hand Pane) the Custom Scale).  Now plug in your Device, open it, and create a Task to acquire data from the Device.  In the Voltage Input Setup, note the ability to use Custom Scaling -- choose the Custom Scale you just created.  Note that the Max and Min of the Signal Input range will need to be in "Scaled" units, so if your device goes from -10 to +10 V, you have to be sure you specify Max and Min scaled values that don't exceed these voltages.  Now save your Task.

 

You can now use this Task as a Task Constant for a DAQmx Start Task.  This will cause DAQmx Read to scale the voltages it reads and output "scaled values" in units you defined.  You can, alternatively, use the Create Scale function in DAQmx, but this is a little more complicated ...

 

Bob Schor

0 Kudos
Message 4 of 8
(1,680 Views)
Solution
Accepted by topic author Hulk1978

@Bob_Schor wrote:

Note that the Max and Min of the Signal Input range will need to be in "Scaled" units, so if your device goes from -10 to +10 V, you have to be sure you specify Max and Min scaled values that don't exceed these voltages.


This is the problem.  You need to use the scaled values for the max and min inputs on the Create DAQmx Channel.  So your max and min should really be 6 and 0 respectively.


GCentral
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines
"Not that we are sufficient in ourselves to claim anything as coming from us, but our sufficiency is from God" - 2 Corinthians 3:5
Message 5 of 8
(1,674 Views)

Hmm -- between the time I wrote my previous response and the time it posted, you had posted your code.  It looks a lot like the code I use, except (a) it is in German (which I don't think will cause any problems) and the Error Lines are missing!  I'd add the Error Lines back in (my rule is "If an Error Line is Present, Wire It, with Few Exceptions").  If you get an error when you run the code, it could be a clue to the "bad" function ...

 

Bob Schor

0 Kudos
Message 6 of 8
(1,668 Views)

you have to be sure you specify Max and Min scaled values that don't exceed these voltages. This was the Problem.

 

Thanks all so much

0 Kudos
Message 7 of 8
(1,663 Views)

One small question yet.

Has anyone an example of polynomic calculation? 

X (factor) is clear. But how is about y?

In my example 0-6bar are 1,95V to 9,95V

0 Kudos
Message 8 of 8
(1,651 Views)