CNC Machine with Resolver (7i49)

Hello,

everything is working right now actually, except of multiple Analog outputs. We just get 1 Analog output at once working, just PWMGEN06=Aout0 from mesa 7i49 is working as intended. All other Aouts generates no signal.

We set the enable pin of each pwmgen from 7i48 and 7i49 but just pwmgen06=Aout0 from mesa 7i49 is working, all others still send out 0V with the same settings as pwmgen06.

Maybe there are signals somewhere which overwrite all the other pwmgens, so that just pwmgen06 is useable?

Hope you can understand our problem^^

EDIT: We solved that one, Pwmgen06 has to be enabled to get all other pwmgens working -.-


Best regards

Simon N.

Hello,

we got some problems with our resolvers, we get the 7i49 Resdrv00+ and - sending out a proper sinus wave with 3V peak. But the resolver sends back sinus and cosinus with very low voltage of 0,6V peak-voltage, in Linuxcnc the rawcounts always swings.

But in the frontpanel the values of x,y,z axis dont rise when we move the axis, it just stays at the same value it is when we start linuxcnc. These values seems to raise up slowly but steady and we dont know why it is that way, because the axis didn't move but the resolvers send a steady growing diffrence in position.

Is the 5V of the ATX power supply maybe not enough power to support the 7i49? or do we have to amplify the sinus and cosinus wave from the resolver?

greetings

Simon N.

Are you voltages peak or peak-peak?

You may get more voltage out of the resolvers
at a lower frequency so I would try 2.5 KHz and 5 KHz

.6V peak should be OK (but noisy)

Does the angle pin on the resolver interface follow the resolver position?

Hi,

we use Ubuntu Version 10.04 and EMC 2.5.

We found out, that our resolver expects a sinus and cosinus wave (receiver resolver) as input and would send out a err wave as reference, we got an old resolver here i guess. It is a receiver resolver but our 7i49 seems to expect that its a differential resolver which works the opposite way.

the differential resolver is energized with one signal and expects 2 waves, a sinus and a cos wave to calculate the angle.
the receiver resolver is energized by two waves, a sinus wave and a cosinus wave and reads the angle in the input of err

Is there a possibility to switch the mode of the resolvers in the 7i49, so that it can work as a receiver resolver or do we have to buy a new resolver now?

@PCW: the angle in HAL scope does not react actually it doesn't move much its almost not there. the 3V is just one peak, it would be 6V peak to peak then. We also tried an other frequenzy, we tested it with 2,5kHz,5kHz and 10kHz non of them generates a proper feedback to work with.

here the link:
en.wikipedia.org/wiki/Resolver_%28electrical%29

Greetings

Simon N.

The 7I49 is designed for standard resolvers (one excitation coil and sine/cosine outputs)

If you drive your resolver backwards (drive the single feedback coil) and measure the two drive coils do you get the exitation waveform varying in sine/cosine magnitude when you rotate the shaft?

Hi,

I'll upload the measured sinus and cosinus inputs from the 7i49 while the drive voltage is active with +- ~1,5V into the resolver.



Sinus Wave pick-up coil 1:10


Cosinus Wave pick-up coil 1:10


seems to be just noise!?


greetings

Simon N.

The outputs will be close to 0 at null positions so you need to rotate the
shaft while watching the 'scope to see if the outputs make sense

In any case the outputs have much too low an amplitude to be useful as is.
(is the resolver error pin set?)

It might be fixable by using a gain of ~100 preamp (or hacking the 7I49 to change its input amp gains), but this is just guessing...