reverse analog feedback direction

[wayne g]

Dear All

I have a motion system, where I switch between position control (encoder) and load control (analog feedback).  I have many transducers that are wired and to use on the system.

My problem is, that when in analog feedback, the transducers drive the motor the wrong direction and thus without any control and as a consequence the system becomes unstable and drive to infinity and max velocity.  If I simply swap the output signal from the transducer the system works fine.

Is there a way that I can do this in software either Labview or MAX.  I have not been able to find how and it is not a simple switch of polarity as the system is controlled at a low level by the PID parameters

Thanks for any help and I hope this question makes sense.

wayne

[Jochen]

Wayne,

unfortunately there is no way to reverse the analog feedback on the board. The best solution I can think of would be to subtract the analog feedback signals from a reference voltage by adding an analog subtracter to the signal path of your feedback signal.

E. g. if the voltage range of your feedback signal is 0 - 5 V you could subtract this voltage from a 5 V reference voltage. The result is the reversed voltage.

Best regards,

Jochen Klier
National Instruments Germany