I am trying to find a programming example that relates to my situation.  I need to adjust pump speed thru the use of VFD.  The speed of the pump will be dictated by a pressure.  The pump will only be able to operate between a pre-set range of speeds.  The pressure is being read by an analog output pressure transmitter.

Any help is greatly appreciated! 

Thanks for the quick reply!  This is a great start.  To help clarify, there would be a pressure set point of say 50 bar.  An analog pressure sensor would continuously monitor the pump discharge to try and maintain the 50 bar set point.  If the pressure is below 50 bar, the pump would speed up to try and achieve the 50 bar set point.  Once the set point is reached, the pump would maintain that speed.  The pump can only operate between 1000 RPM and 2000 RPM.  If the pump operates outside of those speeds, it will need to shut down.

Does this help you tailor the exmple a bit more?

For the pressure sensor, the physical pressure range of the transmitters are 0 to 100 psig and they are 4-20 mA analog output.

For the speed control, it is being controlled by a VFD.  The VFD sends a 4-20mA signal out.

I agree, the controller can only tell the VFD more or less speed within speed max/min set points.  It would be nice if the controller knew what speed the motor and pump were running at via a feedback or speed monitoring input.

I apologize for lack of information.