error in Simple PID

[macsmith]

The LabVIEW supplied "Simple PID" vi contains an error which disables
the Integral function.  The "First Call?" node is located outside of
the main loop and is therefore only evaluated once.  Consequently,
each time around the loop the value selected for "prev error sum" is
always 0.  Moving the "First Call?" node to the inside of the loop
cures the problem.