Negative PID control gains possible?

[beginner]

When seeting the control gain of a PID controller, it allows me to type a negative gain; but it doesn't seem to respond properly. Is it really taking the negative number or it's just internally truncating to zero?

[Chad_H]

Which VI were you using? Which version of LabVIEW are you using?

With General PID Simulator.VI found in "C:\Program Files\National Instruments\LabVIEW 6\examples\pid\Prctrlex.llb" negative gains can be used (causing instability).

Regards,

Chad H.
Application Engineer
National Instruments
http://www.ni.com/ask