Rockwell Automation DeviceLogix System User Manual - Manual (Page 31)

Publication RA-UM003B-EN-P - February 2010 31
Navigate the Function Block Editor Interface Chapter 2
The PID function block scales the process variable, using the
following formula:
The setpoint and zero-crossing deadband should be scaled to
engineering units.
Status Parameters
Status parameters allow you to monitor the control algorithm running
status, using the Alarm parameter's bit field as described here:
• Bit 0: CV is below minimum output limit (0=no; 1=yes)
• Bit 1: CV is above maximum output limit (0=no; 1=yes)
• Bit 2: Error is within deadband (0=no; 1=yes)
• Bit 3: Deviation is alarmed high (0=no; 1=yes)
• Bit 4: Deviation is alarmed low (0=no; 1=yes)
• Bit 5: SP is out of range (0=no; 1=yes)
• Bit 6: PV is out of range (0=no; 1=yes)
• Bit 7~15: Reserved
CV Min (at 0%) REAL 0.0 Minimum value for the unscaled Control
Variable (CV).
This parameter cannot be configured when the
DeviceLogix logic is in the Run mode.
Positive Deviation
Alarm Limit REAL 0.0 High deviation alarm from the set point.
Negative Deviation
Alarm Limit REAL 0.0 Low deviation alarm from the set point.