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PIDB Listing
/****************************************************************************/
/*
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 E1415A controller module.
/* once per scan trigger by main().
/* 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.
/* 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.)
/* output will persist for the duration of all alarm conditions.
/* Status word bits will also persist for the alarm duration.
/* 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.
/* user can change the output by changing the Man_out variable.
/* 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
Appendix D
It performs Proportional, Integral
The alarm condition will cause
The output will be held at its last value.
This algorithm is called
The alarm channel digital
PID Algorithm Listings
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