switch feedback on the fly

[varmih]

Hello.

My application uses an encoder feedback for the initial positioning of the DC motor. However, in the latter part of the test, an analog signal from a force sensor must be the positioning feedback.

Is it possible to switch between encoder and analog feedback devices on the fly without reinitializing the controller (PCI-7344, LabVIEW 7.1)?

Is there any example code for on-board programming?

Thank you.

[Jochen]

This a quote from an answer from Rodj that he posted in another context:

"The NI-735x motion controllers does support changing feedback on the fly. This is a new feature in the NI-Motion 6.1.5 update. You no longer have to disable the axis to change the feedback source. The only requirement now is that you are not performing a move. I have seen this used successfully in another application."

Unfortunately the 734x motion controllers don't support this feature. Still you won't have to reinitialize the controller to change the feedback source. You will just have to disable the axis, change the feedback source and reenable the axis again.

Best regards,

Jochen Klier
National Instruments Germany

[varmih]

Jochen,

Is it possible to do this feedback switch with disabling/enabling axis in an on-board program? Is there any available example code, or this is the straight-forward operation without any underwater stones?

Thank you.

[varmih]

Should I download NI-Motion 6.1.5 update, or 6.1.2 version is enough if in any event I have to disable/enable the axis?

[Jochen]

I haven't found examples doing the feedback source change but as you state this is a straight forward process and yes it should work in an onboard program.

6.1.5 contains some desirable bugfixes so I would recommend installing this version.

[Rodj]

Changing feedback on the fly without disabling/enabling the axis is only supported on the NI-735x series motion controllers. This can be done in an onboard program, but we do not have examples of this yet.

The NI-733x/4x series motion controllers will require the axis to be disabled/enabled whether you do in from the host or in an onboard program.

Rodger S.