AD2S1210 looking at COS and SIN in x-y mode on a scope

HI Philip314159,

   Kindly share scope shots of what you observe. Thanks.

Regards,

Jonathan

Well I figured out that I get the circle that I expect when I go to x-y

mode if I do not try to center the display.

COS and SIN have a DC offset so the circle appears in the upper right

hand corner of my display.

I have scope photos of SIN SINLO and (SIN - SINLO)

The attached photo shows these signals raw but if I average them the

trace is much thinner.  So I am wondering why the trace is so wide.  I

see the same width on the exc output as well.

I attached a picture of SIN - COS and it should be a straight line but

instead I get two lines which means there is some jitter that I cannot

explain.

thanks for your help.

Phil

Also I notice that the SIN COS inputs have a high impedance.  I have the

same circuit as the AD2S1210 eval board (attached) and I am wondering if

this circuit is the best one for working with a servo motor that has a

switching power supply.

I have it operational and it is working fine but I was just wondering

about the high impedance inputs.

Maybe there is a better circuit for working with switching servo drives.

Phil

Hi Jonathan,

Please see my attached scope photos.

The scope photos are for a two foot cable between the resolver and the

AD2S1210.

I put a 345 foot cable between the resolve and the AD2s1210 and I see a

voltage Increase

between SIN - SINLO of about 0.5 volts.  Do you have any idea why the

voltage would increase ?

thank you

Phil

Hi Phil,

   Some impedance will surely contribute offset with the system. The long cable and the traces can be a source of offsets. Have you tried using a resolver with a shorter cable? Switching power supply can contribute noise in to the system.

Regards,

Jonathan