M301L 65
76 FB @ MAX (MAXIMUM FEEDBACK VALUE)
This parameter should be set to the value of the process variable that corresponds to the
maximum transducer feedback signal (10 VDC or 20 mA).
NOTE: If a reverse acting feedback device is being used, FB @ MIN should be set
to the maximum process variable value, and FB @ MAX should be set to
the minimum process variable value.
77 P GAIN (PROPORTIONAL GAIN)
This parameter setting represents the speed command output (in % of maximum speed)
that results from each 1% of error (1% of Parameter 75 - FB @ MIN or 76 - FB @ MAX,
whichever is larger).
Example: If P GAIN is programmed for 5%, and the error (difference between setpoint
and feedback) is 10%, the speed command output of the Proportional term
is 50% (10 x 5 = 50) of maximum speed.
78 I GAIN (INTEGRAL GAIN)
This parameter setting represents the ramp rate of the speed command output (in % of
maximum speed per second) that results from each 1% of error.
Example: If I GAIN is programmed for 0.5 seconds, and the error is 5%, the rate of rise
of the speed command output of the Integral term is 2.5% (0.5 x 5 = 2.5) of
maximum speed per second.
79 D GAIN (DIFFERENTIAL GAIN)
This parameter setting represents the speed command output (in % of maximum speed)
that results from each 1% per second change in the error.
Example: If D GAIN is programmed for 5 seconds, and the error is increasing at 2%
per second, the speed command output of the Differential term is 10% (5 x
2 = 10) of maximum speed.
NOTE: Differential gain is used as a “shock-absorber” to dampen overshoots in fast-
acting systems. However, it can be very sensitive to “noise” on the feedback
signal and to digitizing errors, so it must be used with caution.
80 PID ACC (PID ACCEL/DECEL)
This parameter sets the acceleration and deceleration rate of the setpoint reference into
the PID unit. When the setpoint changes, this function will “filter” the input to the PID unit
by ramping the setpoint reference from the previous value to the new value. This will
help prevent overshoots that can occur when the PID control attempts to respond to step
changes in setpoint, resulting in smoother operation. If PID ACC is set to 0.0 seconds,
it is effectively disabled.
81 MIN ALRM (PID MINIMUM ALARM)
This parameter setting represents the value that the feedback signal (in PID mode) or
speed reference signal (in open-loop speed mode) must fall below to activate the MIN/
MAX ALARM output (refer to Parameters 52, 53, and 54).
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