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TECHNICAL REFERENCE
SERVICE
MANUAL
VF-SERIES
corner. The corner will be rounded. It also means that if the two motions are parallel or nearly parallel, there will be a smooth
transition from one stroke to the next.
Rapid moves have a slightly different operation when continuous cutter mode is active. Acceleration for the next motion is
started when the axes being moved all fall within the In Position Limit Parameters 101, 102, 103, and 104. These
parameters have units of encoder steps. Rapid moves will also decelerate at the constant accel/decel limit until the speed
drops below that for exponential accel/decel (see example above giving 159 inches per minute). Parameter 57 can be used
to override this.
To prevent the rounding of corners, you can specify exact stop either with G09 (non-modal) or with G61 (modal). When
either of these is active in a motion, all of the axes are brought to an exact stop, at zero speed, before the next motion is
started.
The tool path in a circular move (G02 or G03) is not changed by the exponential acceleration/deceleration so there is no error
introduced in the radius of the cut unless the speed exceeds that for exponential accel/decel (see example above giving 159
inches per minute).
4.3 SERVO DRIVE ASSEMBLY (BRUSH)
The servo drive assembly is on the left side of the main control cabinet and about halfway down. Never work on the servo
drive assembly until the small red CHARGE light goes out. This light is at the top of the circuit card at the center of the
assembly. Until this light goes out, there are dangerous voltages in the assembly EVEN WHEN POWER IS SHUT OFF. This
assembly contains four servo drive cards, a Servo Distribution card, and a fan.
4.4 160 VOLT DC POWER SUPPLY (BRUSH)
The Servo Distribution card contains a DC power supply that produces an unregulated voltage between 145 and 175 volts.
This is derived from the three-phase 115V AC coming from transformer T1. The nominal 160V DC is supplied to the four
servo drive cards for the X, Y, Z, and A axes and to the tool changer. This supply is filtered by two capacitors in parallel for
a total of 4000 Mfd. A soft charge-up of these capacitors is provided by a small resistor that is bypassed by a relay when the
servos are on.
The negative side of the 160V power supply is always connected to chassis ground. This means that when the relays on
SDIST are released, all DC power is disconnected and the drives are safe. This also includes the tool changer that uses the
160V buss to drive the tool changer motors.
The minimum DC buss voltage is 145V and anything lower will result in an alarm. The maximum voltage is 185V and
anything above this will cause heating of the servo regen load resistor. Anything above 190V will cause an alarm.
4.5 SERVO COOLING FAN (BRUSH)
There is a cooling fan on the servo drive assembly to help cool the servo drive cards. It blows air up past the servo drive
cards in order to support convection cooling. The fan power is supplied from SDIST by P7.
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