I am trying to measure current from Ignition coil(12V, 4.5A). i used arduino to measure current. And it worked good. And i connected the ACS712 signal pin to NI DAQ 9215. At zero current the output voltage is 2.5v( ACS offset votlage ) which is showing correct in LABVIEW 2017 . But there is no change in voltage when the ignition coil is turned on.
This is thing i got when i measured the signal from current sensor using oscilloscope.
I found the problem for my question. i placed acs-712 to lower side of MOSFET and measured the signal in oscilloscope. and i got the output signal in LABVIEW also.
But the signal is sill noisy in LABVIEW oscillates between 2.5 to 4. I think i should filter the signal.