Dynomotion

Group: DynoMotion Message: 7143 From: funncarsmi Date: 3/31/2013
Subject: DAC output voltages
I read that DAC outputs 0-3 have a 10V output, while 4-7 are limited to 5V. In another section it seems that all DAC 0-7 are 10V output. Which is it suppose to be? I decided to measure it:

When trying to set my spindle speeds, I was working with DAC4 and noticed a nice linear relationship where every 20 counts added 0.20V ....until I hit 1990 counts (9.62V). 1997 counts = 9.65 volts and adding any additional counts made no difference in the output voltage. (2000 counts = 9.65Vm 2046 counts = 9.65V). This is pretty far off from 10V, but if it is suppose to only be providing 5V that is a lot of headroom. What should DAC4 provide?

I then switched to DAC3 (which is planned for my 4th axis that in't complete yet). DAC3 continues to increase voltage to 9.99V which equates to 2046 counts. (entering 2047, 2048, 2049, 2050 does not provide 10.0V ....but I have no complaints about 9.99V, that seems within tolerance to call it 10V). I just find it odd that DAC4 has 4.6V of headroom and DAC3 has -.01V.

I have the spindle speed working well using DAC4, but I am giving up top RPM speed. My spindle only runs 3300 max RPM with 10V, so I would rather not give up any top RPM by limiting myself to 9.65. More importantly, I definitely don't want to be running 9.65 volts out of DAC4 if it should be limited to 5V.

Should all the DAC voltages support +/-10V? If not, what are the lower voltages and for which DACs?

Regards,
Gregg
Group: DynoMotion Message: 7144 From: funncarsmi Date: 3/31/2013
Subject: DAC output voltages
I read that DAC outputs 0-3 have a 10V output, while 4-7 are limited to 5V. In another section it seems that all DAC 0-7 are 10V output. Which is it suppose to be? I decided to measure it:

When trying to set my spindle speeds, I was working with DAC4 and noticed a nice linear relationship where every 20 counts added 0.20V ....until I hit 1990 counts (9.62V). 1997 counts = 9.65 volts and adding any additional counts made no difference in the output voltage. (2000 counts = 9.65Vm 2046 counts = 9.65V). This is pretty far off from 10V, but if it is suppose to only be providing 5V that is a lot of headroom. What should DAC4 provide?

I then switched to DAC3 (which is planned for my 4th axis that in't complete yet). DAC3 continues to increase voltage to 9.99V which equates to 2046 counts. (entering 2047, 2048, 2049, 2050 does not provide 10.0V ....but I have no complaints about 9.99V, that seems within tolerance to call it 10V). I just find it odd that DAC4 has 4.6V of headroom and DAC3 has -.01V.

I have the spindle speed working well using DAC4, but I am giving up top RPM speed. My spindle only runs 3300 max RPM with 10V, so I would rather not give up any top RPM by limiting myself to 9.65. More importantly, I definitely don't want to be running 9.65 volts out of DAC4 if it should be limited to 5V.

Should all the DAC voltages support +/-10V? If not, what are the lower voltages and for which DACs?

Regards,
Gregg
Group: DynoMotion Message: 7145 From: funncarsmi Date: 3/31/2013
Subject: DAC output voltages
I read that DAC outputs 0-3 have a 10V output, while 4-7 are limited to 5V. In another section it seems that all DAC 0-7 are 10V output. Which is it suppose to be? I decided to measure it:

When trying to set my spindle speeds, I was working with DAC4 and noticed a nice linear relationship where every 20 counts added 0.20V ....until I hit 1990 counts (9.62V). 1997 counts = 9.65 volts and adding any additional counts made no difference in the output voltage. (2000 counts = 9.65Vm 2046 counts = 9.65V). This is pretty far off from 10V, but if it is suppose to only be providing 5V that is a lot of headroom. What should DAC4 provide?

I then switched to DAC3 (which is planned for my 4th axis that in't complete yet). DAC3 continues to increase voltage to 9.99V which equates to 2046 counts. (entering 2047, 2048, 2049, 2050 does not provide 10.0V ....but I have no complaints about 9.99V, that seems within tolerance to call it 10V). I just find it odd that DAC4 has 4.6V of headroom and DAC3 has -.01V.

I have the spindle speed working well using DAC4, but I am giving up top RPM speed. My spindle only runs 3300 max RPM with 10V, so I would rather not give up any top RPM by limiting myself to 9.65. More importantly, I definitely don't want to be running 9.65 volts out of DAC4 if it should be limited to 5V.

Should all the DAC voltages support +/-10V? If not, what are the lower voltages and for which DACs?

Regards,
Gregg
Group: DynoMotion Message: 7146 From: funncarsmi Date: 3/31/2013
Subject: Re: DAC output voltages
After 5 minutes I received a message of "timed out message not sent". I retry, and now I have 3 posts of the same message?

Sorry!! Tom I don't know if you have the control to wipe out the duplicates.
Group: DynoMotion Message: 7147 From: Bengt Sjoelund Date: 3/31/2013
Subject: Re: DAC output voltages
--- In DynoMotion@yahoogroups.com, "funncarsmi" <funncars@...> wrote:
>
> After 5 minutes I received a message of "timed out message not sent". I retry, and now I have 3 posts of the same message?
>
> Sorry!! Tom I don't know if you have the control to wipe out the duplicates.
>

You as a thread starter can DELETE the messages, lower left corner within the message.
Cheers
Bengt
Group: DynoMotion Message: 7151 From: funncarsmi Date: 3/31/2013
Subject: Re: DAC output voltages
Bengt,
Thank you. I never realized that.

Gregg


> You as a thread starter can DELETE the messages, lower left corner within the message.
> Cheers
> Bengt
>
Group: DynoMotion Message: 7154 From: Tom Kerekes Date: 3/31/2013
Subject: Re: DAC output voltages
Hi Gregg,

I think you are confusing our old KMotion Controller with a KFLOP+Kanalog Controller.  Kanalog has 8 +/- 10V analog outputs that are all the same.  The outputs were not designed to be perfect as they usually do not need to be for a servo system.  They utilize several 1% resistors so the output can be off by several percent.  Nominally they are designed to be scaled to be a bit high so you always get the full 20V range.

You stated 4.6V but I think you meant to say 0.46V of error.  That still seems a bit high (2.3% of 20V).  It shouldn't clip either at a number less than 2047 so I don't understand that.  But usually you can scale up your amplifier anyway.  Can't you do this?  It isn't usually necessary to have full 10V to get full speed from your amplifier.

Regards
TK




Group: DynoMotion Message: 7157 From: funncarsmi Date: 4/1/2013
Subject: Re: DAC output voltages
Tom,
My biggest concern was if the output was only 5V, and if I would damage anything by driving DAC4 to 10V. You answered that question: it is a 10V output.
Scaling to 2000 (1997)instead of 2047 will not be a problem. Over the weekend someone forwarded the directions to my 1982 vintage "Spin Control" board, so now I can now adjust for the lower voltage too.

I never expected the outputs to be a perfect 10.00V. The combination of the scaling stopping at 1997 counts and not reaching the full 10 volts, made me second guess the voltage handling capability of DAC4. Figured it was better to ask than to plan to routinely drive 10 volts through a 5V circuit.

Thanks,
Gregg




--- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@...> wrote:
>
> Hi Gregg,
>
> I think you are confusing our old KMotion Controller with a KFLOP+Kanalog Controller.  Kanalog has 8 +/- 10V analog outputs that are all the same.  The outputs were not designed to be perfect as they usually do not need to be for a servo system.  They utilize several 1% resistors so the output can be off by several percent.  Nominally they are designed to be scaled to be a bit high so you always get the full 20V range.
>
> You stated 4.6V but I think you meant to say 0.46V of error.  That still seems a bit high (2.3% of 20V).  It shouldn't clip either at a number less than 2047 so I don't understand that.  But usually you can scale up your amplifier anyway.  Can't you do this?  It isn't usually necessary to have full 10V to get full speed from your amplifier.
>
> Regards
> TK
>
>
>
>
>
>
> ________________________________
> From: funncarsmi <funncars@...>
> To: DynoMotion@yahoogroups.com
> Sent: Sunday, March 31, 2013 8:39 AM
> Subject: [DynoMotion] DAC output voltages
>
>
>  
> I read that DAC outputs 0-3 have a 10V output, while 4-7 are limited to 5V. In another section it seems that all DAC 0-7 are 10V output. Which is it suppose to be? I decided to measure it:
>
> When trying to set my spindle speeds, I was working with DAC4 and noticed a nice linear relationship where every 20 counts added 0.20V ....until I hit 1990 counts (9.62V). 1997 counts = 9.65 volts and adding any additional counts made no difference in the output voltage. (2000 counts = 9.65Vm 2046 counts = 9.65V). This is pretty far off from 10V, but if it is suppose to only be providing 5V that is a lot of headroom. What should DAC4 provide?
>
> I then switched to DAC3 (which is planned for my 4th axis that in't complete yet). DAC3 continues to increase voltage to 9.99V which equates to 2046 counts. (entering 2047, 2048, 2049, 2050 does not provide 10.0V ....but I have no complaints about 9.99V, that seems within tolerance to call it 10V). I just find it odd that DAC4 has 4.6V of headroom and DAC3 has -.01V.
>
> I have the spindle speed working well using DAC4, but I am giving up top RPM speed. My spindle only runs 3300 max RPM with 10V, so I would rather not give up any top RPM by limiting myself to 9.65. More importantly, I definitely don't want to be running 9.65 volts out of DAC4 if it should be limited to 5V.
>
> Should all the DAC voltages support +/-10V? If not, what are the lower voltages and for which DACs?
>
> Regards,
> Gregg
>