VXi VT1529A/B 用户手册

To set up the algorithms for this example:

1. Define the global variable <cold_setpoint>.

ALG:DEF 'GLOBALS','static float cold_setpoint;'

2. Define the following algorithm language code as ALG1, the ratio 

station algorithm.

static float hot_flow, cold_hot_ratio;
static float cold_temp = 55, hot_temp = 180, product_temp = 120;
hot_flow = I108;

/* get flow rate of cold supply */

/* following line calculates cold to hot ratio from supply and product temps */
cold_hot_ratio = (hot_temp - product_temp) / (cold_temp - product_temp);
cold_setpoint = hot_flow * cold_hot_ratio;  /* output flow setpoint for ALG2 */

3. Modify a PIDA algorithm so its setpoint variable is the global 

variable cold_setpoint, its input channel is I109 and its output channel 
is O116 and Define as ALG2, the cold supply flow controller.

/*  Modified PIDA Algorithm; comments stripped out, setpoint from global,
    inchan = I109, outchan = O116
*/
     /* the setpoint is not declared so it will be global */

  

    static float P_factor = 1;

 

    static float I_factor = 0;
    static float D_factor = 0;
    static float I_out;
    static float Error;
    static float Error_old;

flow transmitter

flow transmitter

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GLOBAL

I108

O116

I109

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