APP005.TXT  TestPoint Application Note


APP005.TST  Associated Source File 


PID.TST  Associated Source File 


(c) Capital Equipment Corporation 1995





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Closed Loop Control Using PID


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TestPoint can perform closed loop control using the PID algorithm.  





Closed loop control under Windows is limited in ways that 


pertain to accuracy and safety.  Mouse movement and key presses 


or any user initiated activity takes precedence over the 


currently running application.  These events introduce a time 


lag in the control system that could result in bad data, 


improper control and system instability.  Therefore, no other 


applications should be running and no interactive procedures are 


allowed.  This is true regardless of measurement speed.  The 


operative buzz words are preemptive multitasking.  Windows 


doesn't have preemptive multitasking and cannot assign a higher 


priority to TestPoint than user initiated events.