VXI VT1422A - Manual (Page 187)

Creating and Running Algorithms 185 Chapter 6
Accessing the VT1422A's Resources
This section describes how algorithms access hardware and software
resources provided by the VT1422A. The resources are listed below:
•
I/O channels.
•
Remote Scan Status variables.
•
Global variables defined before algorithms are defined.
•
The constant ALG_NUM which the VT1422A makes available to the
algorithms. ALG_NUM = 1 for ALG1, 2 for ALG2, etc.
•
User defined functions defined with the ALG:FUNC:DEF command.
•
The Current Value Table (CVT) and the data FIFO buffer (FIFO) to
output algorithm data to the application program.
•
VXIbus Interrupts.
/* GLOBALS you define with ALG:DEF GLOBALS... go here */
/* global variable First_loop equals 1 until all algorithms called */
static float First_loop; /* global value set to 1 at each INIT */
/**************************** function main() ****************************/
/*The VT1422A driver creates main() at INIT time. This example
shows a main created after 2 algorithms have been defined. */
main()
{
/********* declaration of variables local to main() ********/
static float State_1, Ratio_1, Count_1; /* created if alg1 defined */
static float State_2, Ratio_2, Count_2; /* created if alg2 defined */
/********* this section created if ALG1 is defined ********/
Count_1 = Count_1 - 1; /* Count_1 used for ALG:SCAN:RATIO */
if (Count_1 <= 0) { /* test for ratio met (<=0 means execute)*/
Count_1 = Ratio_1; /* Count_1 = ALG:SCAN:RATIO setting */
if (State_1) alg1(); /* if ALG:STATE ALG1,ON, call alg1 */
}
/********* this section created if ALG2 is defined ********/
Count_2 = Count_2 - 1; /* Count_2 used for ALG:SCAN:RATIO */
if (Count_2 <= 0) { /* test for ratio met (<=0 means execute)*/
Count_2 = Ratio_2; /* Count_2 = ALG:SCAN:RATIO setting */
if (State_2) alg2(); /* if ALG:STATE ALG2,ON, call alg2 */
}
First_loop = 0; /* reset First_loop after last alg has been called */
}
/* ************************ end function main() *************************/
ALG1() /* this function shell created by ALG:DEF 'ALG1'.... */
{
const int ALG_NUM = 1; /* created by driver to ID this algorithm */
/********* Your algorithm code goes here **********/
}
ALG2() /* this function shell created by ALG:DEF 'ALG2'.... */
{
const int ALG_NUM = 2; /* created by driver to ID this algorithm */
/********* Your algorithm code goes here **********/
}
Begin algorithm "shells"
(built by VT1422A's driver)
End main() function
Begin main() function
(built by VT1422A's driver)
Global variables area
First_loop declared by
VT1422A's driver
Figure 6-1. Source Listing of Function main( )
Your algorithms go here