Manual

EFB-Quad and PID-Quad Adjustments:
There are two adjustments available on each of the four channels on an EFB-Quad, and eight
adjustments per channel on an PID-Quad. These are:
1) Proportional (‘P’) or Gain: This controls how much the valve will be opened for a given distance
between the commanded and actual positions of a movement. This control is bypassed when
there is an error condition in the feedback transducer wiring or on power-up.
Turning this control clockwise will increase its effect. Turning it counterclockwise reduces its
effect. When turned fully counter clockwise, it has no effect at all.
When the Proportional control is turned too high, the movement will oscillate
uncontrollably. Set it too low and the movement will move sluggishly.
2) Integral (PID-Quad only): This is the control that sets the final ‘suck in’ to the commanded
position. When a motion stops near the commanded position, but not exactly on it, the Integral
comes into play. When the position error is small, the voltage sent to the valve is usually too
small to overcome the valve/cylinder ‘stiction’ to get the movement to reach the final position.
What the integral does is to provide a gradually increasing voltage to the valve until it
overcomes the valve/cylinder stiction and the movement moves that last little bit to reach the
final position.
Turning this control clockwise will increase its effect. Turning it counterclockwise reduces its
effect. When turned fully counter clockwise, it has no effect at all.
When the Integral on a movement is set too low, the movement will not reach the
commanded position when the distance between the commanded position and the actual
position is small. This will widen the deadband of the movement. If the Integral is turned too high,
you will see the movement constantly ‘seeking’ the commanded position. This looks like a low
speed oscillation on the movement.
3) Derivative (PID-Quad only): This controls the PID feedback loop’s ability to respond to quickly
changing commands. Think of the derivative as the accelerator pump in an automobiles’
carburetor. When you step on the gas quickly, it gives an extra little squirt of gas to the engine to
get it to accelerate quickly. When you accelerate slowly, the accelerator pump (and the
Derivative term of the PID loop) have no effect.
Turning this control clockwise will increase its effect. Turning it counterclockwise reduces its
effect. When turned fully counter clockwise, it has no effect at all.
The Proportional (Gain) control and the Derivative must be adjusted interactively. When the
Derivative is set too low, the movement won’t follow fast changes in commands as quickly as it
would otherwise. If the Derivative is set too high, then the movement may start quite quickly, but
then get ahead of the commanded position and will have to decelerate to allow the
Proportional term to catch it.
4) Dither (PID-Quad only): This control adds an approximately 60 Hertz ‘triangular’ signal to the
output sent to the valve. Some valves can benefit from such a signal in that by keeping moving,
they will then respond to actual commands much more quickly.
Turning this control clockwise will increase its effect. Turning it counterclockwise reduces its
effect. When turned fully counter clockwise, it has no effect at all.
If the valve you are using will benefit from a dither signal, the specification sheet will usually
indicate this. If there is no indication whether a dither signal will help your valve, adjust the
movement as usual, but keep it a little more sluggish than you want the final speed. Then crank
in some dither. If the speed of the movement increases, then there is probably some benefit to
keep it in. If there is no change, then there is no reason to use it.
5) Null (PID-Quad only): Nulling is used to set the valve so that when it has no voltage being sent
to it, there is no movement in the cylinder.
Ideally the valve should be adjusted mechanically with the wires from the feedback card
GILDERFLUKE & CO. • 205 SOUTH FLOWER ST. • BURBANK, CALIF. 91502-2102 • 818/840-9484 • FAX[phone]
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