compact fieldpoint

[0807]

hi

actually the sub VIs works perfectly,The temperature part for channel 1 is OK and its only channel 0 that is giving me proplem. i am measuring current form a 500W lamp AC using a current transformer ASM 010. when i using a digital multi meter to measures the voltage across the transformer i get 0.0075V and and if i were to input the current calculation in i should get around 2A using the calculation but my reading i got varies from -2 to 3 which i don;'t understand

[Wayne.C]

0807,

Things change a bit when you measure AC signals.  FP is not the same as a multimeter.  When you measure AC with a multimeter it takes many samples of the AC waveform and then calculates the value.

Each FPRead takes a single reading.  It does not care if the signal being samples is AC or DC.  If you just randomly sample an AC signal you will get readings that don't make sense.  To measure AC you need to take many samples and then analyze the resulting data to determine the ac value.  You need to make sure that the sampling rate is at least 10 times greater that the frequency you are sampling.