LabVIEW
Arduino Current and Voltage Monitering and labview
Hi all
This is the second time i am using labvew and the arduino i have limited experience with labview programming and i am trying to understand how to achieve the same results from the below arduino code. basically i have a CT conneted to the arduino and it uses this code
const int currentPin = 3;
const unsigned long sampleTime = 100000UL;// sample over 100ms, it is an exact number of cycles for both 50Hz and 60Hz mains
const unsigned long numSamples = 250UL;
const unsigned long sampleInterval = sampleTime/numSamples; // the sampling interval, must be longer than then ADC conversion time
const int adc_zero = 510;void setup()
{
Serial.begin(9600);
}
void loop()
{
unsigned long currentAcc = 0;
unsigned int count = 0;
unsigned long prevMicros = micros() - sampleInterval ;
while (count < numSamples)
{
if (micros() - prevMicros >= sampleInterval)
{
int adc_raw = analogRead(currentPin) - adc_zero;
currentAcc += (unsigned long)(adc_raw * adc_raw);
++count;
prevMicros += sampleInterval;
}
}
float rms = sqrt((float)currentAcc/(float)numSamples) * (75.7576 / 1024.0);
Serial.println(rms);
}
I would like to read AC Voltage and current of a motor and also control a contractor from labview .Currently i have interfacing circuit that gives me an AC wave form with a refrence of 2.5V the curcuit looks like this below
The output of this circuit will have a bias of 2.5V of which it will oscillate around and remain positive .Both my current and voltage circuits has the same type of analog output signal . There are arduino libraries already created to do these functions . I am just trying to do the same thing in labview . below is a link to the libraries .
[url]http://openenergymonitor.org/emon/buildingblocks/arduino-sketch-voltage-and-current/url]
i have been trying to get this to work but i am not having much luck .i used the analog read example and modified it a bit , i see the loop frequency is 130Hz . i am trying to read a a sin wave that has a ref of 2.5 the idea is to square the sample values then find the average of at least at least 120 samples then sqrt that value and scale it to match my current range . so far this works but the accuracy of the measurements are off a bit . There are also other stuff to consider such as phase shift in sampling and calibration .
i would have to read at least 9 analog inputs at once. I am not to sure i can achieve this.
I am also considering program the arduino since there are libraries already created to take the readings .I will then have labview display them by serial data sent from the arduino . i would also like to control a contractor via labview via serial communication also .
I have to sample at least twice the frequency of the mains and would also have to sample multiple analog inputs at the same time also
Can anyone give me some advise about if this is even possible ??
Attached is the vi i have created so far
Thank you
gary
