11-08-2010 05:01 AM
Hi there,
I need to find the gain of an operational amplifier. I have a functional test system using NI PXI and as software LabVIEW V8.5 and TestStand V4.0
How do I implement the following code in TestStand?
Perform a “binary search” type of procedure to find the limit of the input range, to a resolution of about 20mV.
For the differential amplifier positive signals (i.e. above 2.5V) the limits of the search range are +3V to +5V.
Go round the loop 7 times, each time round the loop halves the search range.
27 = 128 so starting with a 2V range the final result will be within about 2÷128 = 15.6mV of the true value.
See BinarySearch.xls for an example in excel of how the search works.
low = +3V
high = +5V
count = 7
do
vpos = (low + high) / 2
vneg = vpos -1
if output ok then low = vpos
else if output not ok then high = vpos
count = count -1
while count > 0
output vpos
count = 7
For count = 1 to 7 #### either integer count or define step size =1
vpos = (low + high) / 2
vneg = vpos -1
if output ok then low = vpos
else if output not ok then high = vpos
count = count -1
Next count
output vpos
I have started to implement in TestStand up to, please see attachment.
Any suggestion are very welcome.
Thank you for your time.
Marken
11-10-2010 04:02 PM
I'd recommend doing this algorithm in LabVIEW as this is will be significantly slower in TestStand.
11-11-2010 02:08 AM
Hi Snowpunter,
Thanks for your replay.
I will try to do it in LaVIEW but I am not that skilled. So if I get stuck can I post the vi and maybe you can give me some hints?
Regards
Marken