"configure axis resources.flx" this function confuse me by the axis setting

[dirsing]

I use 7344 control card, LabView 6.1

In the "configure axis resouces.flx" fuction,I can set the primary output,primary feedback, secondary output, secondary feedback.

If I want to use the closed loop control,
I set the primary output "DAC1" to actuate the system,
and primary feedback "ADC1" to complete the the closed loop system,is it right

[Rodj]

This is correct if your feedback device is analog based. If your feedback is an encoder then you would use Encoder1 for the primary feedback.

Most systems just need to use the primary output and feedback.

Rodger S.

[dirsing]

Thank for your reply
But,I have another question

If I want to complete the closed loop control,
I need an error signal that is "input-output"

now,I have an input signal that is "primary output=DAC1" to actuate the system
,and an output signal that is "primary feedback=ADC1"

where is the error signal "input-output"?
does it calculate in the embeded cpu "MC68331",and output from "primary output"?



Thank for your reply

[Jochen]

Sorry but I don't understand this question. What's the purpose of the error signal. Which device should send it? Which device should receive it? What's the connection to the feedback and control signals? Are you looking for a bidirectional digital signal?

"...now,I have an input signal that is "primary output=DAC1" to actuate the system
,and an output signal that is "primary feedback=ADC1" "

Is this a statement from the drive's point of view?

Best regards,

Jochen Klier
National Instruments Germany

[dirsing]

Thank for your reply

I want to use 7344 card to complete closed loop PID control to actuate the piezoactuator
I have a problem how to connect the wire to complete the closed loop control

This is my connectting picture ,am I right?

Thank for your reply

[Jochen]

No, I think your setup should look like this (sorry for the simple ASCII "graphics"):

[Setpoint]------>
............................(-)--> PID -->[Analog Output]--> [G(s)]
[Analog Input]-->
[= feedback]

Is your error signal the difference between setpoint and feedback signal? In the terms of motion control this is called following error and you can read this value with read following error.flx in LabVIEW or with flex_read_follow_err_rtn() in text based programming environments.
While moving the setup is generated dynamically by the trajectory generator on the board.

Jochen

[dirsing]

Thank for your reply

I have a little ideal about how the closed loop PID control work.
In "picture",there are some concept, is that right?
thank you

and I find a example code at

http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3DCAD56A4E034080020E74861&p_node=DZ52469&p_source=external
(Automatic Analog Feedback with FlexMotion)
and
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3E82356A4E034080020E74861&p_node=DZ52469&p_source=external
(Manual Analog Feedback with FlexMotion)

Can they achieve my purpose?
Thank for your reply

[RManion]

Hello,

If you are trying to achieve Motion with Analog feedback, these examples should be what you are looking for. The diagrams that you have attached are not exactly the way I am accustomed to seeing the system described, but are close to what's going on.

If you are trying to figure out what items to wire up, the analog input to the motion system will be the feedback from your piezoactuator, and the analog output of the motion system will be the input to your actuator.

Hope this helps,

Robert