Campbell Scientific CR1000KD CR800 and CR850 Measurement and Control Systems - Page 189

Section 7. Installation CRBasic Example 37. Subroutine with Global and Local Variables 'Global variables are those declared anywhere in the program as Public or Dim. 'Local variables are those declared in the Sub() instruction. 'Program Purpose: Demonstrates use of global and local variables with subroutines 'Program Function: Passes 2 variables to subroutine. Subroutine increments each 'variable once per second, multiplies each by pi, then passes results back to 'the main program for storage in a data table. 'Global variables (Used only outside subroutine by choice) 'Declare Counter in the Main Scan. Public counter(2) As Long 'Declare Product of PI * counter(2). Public pi_product(2) As Float 'Global variable (Used only in subroutine by choice) 'For / Next incrementor used in the subroutine. Public i_sub As Long 'Declare Data Table DataTable(pi_results,True,-1) Sample(1,counter(),IEEE4) EndTable 'Declare Subroutine 'Declares j(4) as local array (can only be used in subroutine) Sub ProcessSub (j(2) As Long,OutVar(2) As Float) For i_sub = 1 To 2 j(i_sub) = j(i_sub) + 1 'Processing to show functionality OutVar(i_sub) = j(i_sub) * 4 * ATN(1) '(Tip: 4 * ATN(1) = pi to IEEE4 precision) Next i_sub EndSub BeginProg counter(1) = 1 counter(2) = 2 Scan(1,Sec,0,0) 'Pass Counter() array to j() array, pi_pruduct() to OutVar() Call ProcessSub (counter(),pi_product()) CallTable pi_results NextScan EndProg 7.8.5 Wind Vector The WindVector() instruction processes wind-speed and direction measurements to calculate mean speed, mean vector magnitude, and mean vector direction over a data storage interval. Measurements from polar (wind speed and direction) or orthogonal (fixed East and North propellers) sensors are supported. Vector direction and standard deviation of vector direction can be calculated weighted or unweighted for wind speed. 189