User manual

IEC61131 User and Reference Manual
April 22, 2008
331
Deadband
The deadband parameter is used by the PID algorithm to determine if the process requires
the control outputs to be changed. If the absolute value of the error is less than the
deadband, then the function block skips execution of the control algorithm. This prevents
changes to the output when the process value is near the setpoint and can reduce wear on
the control elements. Valid range is any value greater than 0.
Full Scale Output
The full% setting is the full-scale output limit in percent of cycle time. For example if the
cycle time is 10 seconds and the full% value is 100 then the maximum duty cycle of the
output% is 100 percent or 10 seconds.
When the zero% value is 0 or greater then the increase output is turned on for the duty cycle
of the output%. When the zero% value is less than zero the decrease output is turned on for
the duty cycle of the output% when the output% is negative.
Zero Scale Output
The zero% setting is the zero scale output limit in percent of cycle time. When the zero%
value is 0 or greater then the increase output is turned on for the duty cycle of the output%.
When the zero% value is less than zero the decrease output is turned on for the duty cycle
of the output% when the output% is negative.
Cycle Time
The cycle time is the floating-point value of the PID algorithm execution period measured in
seconds. Any value greater than or equal to 0.001 seconds (1 ms) may be specified. If the
cycle time specified is less than the scan time of the TelePACE program, the program scan
time becomes the PID cycle time.
Manual Mode Output
The manual mode output% is the value that the output% is set to when the PIDD function
is in manual mode.
Motor Output
When the motor output is set to enabled the increase and decrease outputs are de-
energized when error is within the deadband. When the motor output is set to disabled the
increase and decrease outputs operate continuously based on the output%.
See Also
pida