Option Wiring; Basic Operating Instructions; Control Algorithm Discussion; Pulse-Accumulation Loop Pi Tuning - DART Controls MDP CONTROL Series Instruction Manual

-1 Option Wiring

The -1 option board is a module which allows external up and down push buttons to be wired to the
unit. These buttons operate exactly like the Up and Down buttons on the user interface. This module
is commonly used to allow PLCs or hand-held pendants to operate the front-panel remotely. Wire for
the external buttons are attached via a 3mm European terminal block on the -1 option board. The
buttons are activated by shorting the terminal labeled Com to either the Up or Down terminal.

Control Algorithm Discussion

The MDP series controls are based on a pulse-accumulation algorithm. The advantage to this type of
algorithm is that it allows the control to follow a master process with exceptional long-term accuracy.
The MD10P and MD3P controls have three parameters which allow the user to adjust how aggressively
the units drive the motor to achieve the target speed. These 3 parameters are as follows:
P Gain - This is the proportional gain for the control loop. In pure pulse-accumulation algorithms, there
is no loop error to base a 'P' factor on; therefore, these units must estimate error based on several
control loop factors. Those who are familiar with PID control tuning should be aware that the MD10P
and MD3P control's P Gain is somewhat different than that of standard velocity-form PID algorithms.
The P Gain is a function of instantaneous error, a measure of the difference between the target (desired)
speed and the current speed of the motor.
I Gain -This is the integral gain for the control loop. The I Gain is a function of accumulated error, a
measure of the difference between the target (desired) speed and the current speed of the motor.
Pulse Accumulation Limit - This parameter allows the user to limit the maximum number of pulses
the drive will accumulate prior to intentionally losing count and therefore long-term accuracy. See the
details for parameter 29 in the Parameter Description section.

Pulse-Accumulation Loop PI Tuning

Many applications do not require tuning of the P and I Gain parameters beyond the supplied factory
default settings. If more responsiveness is desired or if the motor oscillates an unacceptable amount when
changing speeds, it may be necessary to adjust the P and I gains to obtain optimal performance.
Increasing the P and/or I gains will cause the control to drive the motor more aggressively. Decreasing
the P and/or I gains will cause the control to perform more sluggishly. Properly tuning the P and I
gains encompasses more than independently adjusting the P and I. The ratio between the two is
very important as well. Although initial tuning can be a time-consuming task, here is a basic outline
of how to proceed:
MICROPROCESSOR
SERIES PC BOARD
-1 OPTION
BOARD
COMMON

Basic Operating Instructions

REMOTE SWITCHING
DOWN UP
-3
-2 -1
UP
DOWN
10