Create Analog OUT (0-10 V) from table -- Voltage "profile"

[WhiteCloud]

Hi everybody,

with LabView and the MyDAQ, I want to control the speed of a motor. The Motor is supported by a  electronic frequency converter which gives the motor the power. The DAQ should simply give a 0-10 Volt control signal to "tell" the frequency converter how much rounds per minute the motor should run.

We want to create several "Voltage-profiles" which can be runned for several times repeatable. For example:

Accelerate in 5 seconds linear to 60 rpm

hold 10 sec. 60 rpm

Accelerate in 5 seconds linear to 100 rpm

Slow down in 20 seconds to 0 rpm

The question:  Is there a way maybe to create a Exel list with our Values and to read them in Labview? Has anyone a idea how we could realize this?

Thank you everybody for your answers,

WhiteCloud

[P@Anand]

Check the attached vi. You have array controls for setting the start and the end points and an array for timing so configure the values and run it. if you want to ramp from 0 to 60 give 0 in start and 60 in end and give 5 sec as time. if you want to hold the data for some time give the start and end as the same.

[WhiteCloud]

Hi  P Anand,

thanx very much for the prompt reply and attached expample which is simply great!!

Unfortunately I am a "Greenhorn" in LabView programming and I just tried to output the analog signal with my DAQ. (See attached file). I get a error message that the output-level is too high (10,001 V, but the DAQ can only 10 Volts maximum). How can I scale that down? The Chart shows although all older signals if you try to set a new profile, can that be resetted?

My target is to control the motor of a test stand with the analog out, and to measure to the same some data like power and voltage of a battery (The sensors give a analog voltage to the DAQ).

How is the best way to measure and log all that data synchron?

Thank you very much, greetings,

Markus alias WhiteCloud

[P@Anand]

No you shouldn't been doing that I was giving the Engineering unit command. What you need to do is you have to convert the Engineering Unit to voltage and send it to DAQ card and always its better to have a saturation at the input of the DAQ write function with +/- 10 as limits. Check the attached example

[WhiteCloud]

Hi P Anand,

thanx again for your help, i just tried to get the "voltage curve" from the graph on the Analog out of the DAQ and failed miserable. Let me as a beginner in Labview programming ask you one more question:

Why does´nt it work to connect simply the "Value to DAQ" to the data input of the DAQ assistant?

The "voltage curve" is on the timeline 40 sec. long. I would excpect that pushing the RUN button once means the VI runs 40 sec. too. Why does it stop already after some 3 seconds?

Hope I´m not wasting your time with my stupid questions....

Thanx again, Markus

[P@Anand · Accepted solution]

It depends on how you are running the loop.if you see my example I am generating 5000 samples for 5 seconds so that means you have to command the DAQ every 1ms. And also holding that much of samples in memory is not a good idea so decrease the sampling rate (1000 to 100 ) and command the DAQ every 10ms. Take example from LV help and try to implement low level vi's and command sample by sample so that it will run for the expected time.

[WhiteCloud]

Ok, i just tried it you were right! Thanx lot for your help!

Markus