Need Help!- Mesa 7I33 Output scale help

[flannman]

Hi All

I am in the middle of doing an EMC retrofit of a Cincinnati Arrow 500 using a mesa 5i20, 7i33 combo. I am new to EMC2 and learning very fast but have come accross something I just cant figure out. Using the pncconf I calculated the output scale to be 40. To get to this I have 3000 rpm analogue servos with a 8mm pitch ballscrew and at full speed this gives 24,000mm/min rapid or 400mm/sec. The servo drive is +-10v analogue driven so therefore the output scale is 1v=40mm/sec. The problem is that when I test the axis it does not go anywhere near the speed it should and at rapid it only does 100mm/sec and not 400. Please can anyone help me on this or point me in the right direction.

Thanks

Flannman

[cncbasher]

check that infact 10v gives you full speed , you may well find the servo drive has been calibrated for a different voltage scale

have you checked that you have 10v from the card and also at the input terminals of the servo drive , you could have losses in the cable , therfore reducing the voltage reaching the servo drive , adjusting the input of the servo drive to compensate to give you full speed , if thats the case .

the easy way is to use one or 2 1.5v battery in series

[flannman]

Cncbasher

Thanks for your reply. The servo drive is set to +-10v and using the open loop control when i put 1v into it the velocity is approximately 40mm/sec which is correct. Also when I set the output scale to 10 i can 9.6v from the card but when set to 40 i can only get 3.5v. Its baffling me.

Flannmann

[PCW_MESA]

Originally Posted by flannman Cncbasher Thanks for your reply. The servo drive is set to +-10v and using the open loop control when i put 1v into it the velocity is approximately 40mm/sec which is correct. Also when I set the output scale to 10 i can 9.6v from the card but when set to 40 i can only get 3.5v. Its baffling me. Flannmann

Perhaps this is just a pncconf limitation. Have you tried closing the loop, so the 7I33 is driven by the output of the PID loop, not pncconf?

[flannman]

PCW_MESA

I have been using the pid loop and configuring the ini file manually due to the limitations of pncconf. I can get very good motion with the output scale set to 10 and i have been doing some pid tuning. Its just when the output scale is set to 40 it is very slow.

Flannman

[PCW_MESA]

Originally Posted by flannman PCW_MESA I have been using the pid loop and configuring the ini file manually due to the limitations of pncconf. I can get very good motion with the output scale set to 10 and i have been doing some pid tuning. Its just when the output scale is set to 40 it is very slow. Flannman

Is it possible the PID components output limit is set to something less than 40? That would account for the output limit

(that said there's no particular reason the output scale needs to be in machine units/sec (output scale of 10 for 10V FS makes sense also). The only advantage I see in setting the output scale to machine units/sec is that it would make the PID loop tuning parameters independent of machine units.