Справочник Пользователя для VXi VT1422A

/********************************************************************************************/
/*  PID_B

*/

/********************************************************************************************/
/*  I/O Channels

*/

/*  Must be defined by the user

*/

/*

*/

/* inchan - Input channel name

*/

/* outchan - Output channel name

*/

/* alarmchan  - Alarm channel name

*/

/*

*/

/********************************************************************************************/
/*

*/

/********************************************************************************************/
/* PID algorithm for VT1422A controller module.  This algorithm is called */
/* once per scan trigger by main().  It performs Proportional, Integral

*/

/* and Derivative control.

*/

/*

*/

/*

*/

/* The output is derived from the following equations:

*/

/* */
/* PID_out = P_out + I_out + D_out + SD_out 

*/

/* P_out = Error * P_factor

*/

/* I_out = I_out + (Error * I_factor) 

*/

/* D_out = ((PV_old - PV) * D_factor) 

*/

/* SD_out = (Setpoint - Setpoint_old) * SD_factor    

*/

/* Error = Setpoint - PV

*/

/*

*/

/* where:

*/

/*   Setpoint is the desired value of the process variable (user supplied) */
/*   PV is the process variable measured on the input channel

*/

/*   PID_out is the algorithm result sent to the output channel

*/

/*   P_factor, I_factor, D_factor and SD_factor are the PID constants

*/

/*  (user supplied)       

*/

/*      

*/

/* Alarms may be generated when either the Process Variable or the

*/

/* error exceeds user supplied limits. The alarm condition will cause

*/

/* an interrupt to the host computer, set the (user-specified) alarm

*/

/* channel output to one (1) and set a bit in the Status variable to

*/

/* one (1). The interrupt is edge-sensitive. ( It will be asserted only

*/

/* on the transition into the alarm state.) The alarm channel digital

*/

/* output will persist for the duration of all alarm conditions. The

*/

/* Status word bits will also persist for the alarm duration. No user

*/

/* intervention is required to clear the alarm outputs. 

*/

/*

*/

/* This version provides for limiting (or clipping) of the Integral,

*/

/* Derivative, Setpoint Derivative and output to user specified limits.

*/

/* The Status Variable indicates when terms are being clipped.

*/

/*   

*/

/* Manual control is activated when the user sets the Man_state variable */
/* to a non-zero value.  The output will be held at its last value.  The

*/

/* user can change the output by changing the Man_out variable.  User */
/* initiated changes in Man_out will cause the output to slew to the

*/

/* Man_out value at a rate of Man_inc per scan trigger.

*/

/* */
/* Manual control causes the Setpoint to continually change to match

*/

/* the Process Variable and the Integral term to be constantly updated     */
/* to the output value such that a return to automatic control will

*/

/* be bumpless and will use the current Process Variable value as the

*/

/* new setpoint.

*/

/* The Status variable indicates when the Manual control mode is active. */
/*  

*/

/* At startup in the Manual control mode, the output will slew to Man_out */
/* at a rate of Man_inc per scan trigger.

*/

/*     

*/

/* At startup, in the Automatic control mode, the output will abruptly

*/

/* change to P_factor * Error. 

*/

/*       

*/

/* For process monitoring, data may be sent to the FIFO and current 

*/

/* value table (CVT).  There are two levels of data logging, controlled

*/

/* by the History_mode variable.  The location in the CVT is based

*/