Galil Motion Control DMC-42 0 Series, User Manual

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Amplifier (Driver)
For each axis, the power amplifier converts a ±10 volt signal from the controller into current to drive the motor.
For stepper motors, the amplifier converts step and direction signals into current. The amplifier should be sized
properly to meet the power requirements of the motor. For brushless motors, an amplifier that provides electronic
commutation is required or the controller must be configured to provide sinusoidal commutation. The amplifiers
may be either pulse-width-modulated (PWM) or linear. They may also be configured for operation with or without
a tachometer. For current amplifiers, the amplifier gain should be set such that a 10 volt command generates the
maximum required current. For example, if the motor peak current is 10A, the amplifier gain should be 1 A/V. For
velocity mode amplifiers, 10 volts should run the motor at the maximum speed.
Galil offers amplifiers that are integrated into the same enclosure as the DMC-42x0. See the section in the
Appendices or
http://galilmc.com/products/accelera/dmc42x0.html for more information.
Encoder
An encoder translates motion into electrical pulses which are fed back into the controller. The DMC-42x0 accepts
feedback from either a rotary or linear encoder. Typical encoders provide two channels in quadrature, known as
MA and MB. This type of encoder is known as a quadrature encoder. Quadrature encoders may be either single-
ended (MA+ and MB+) or differential (MA+, MA-, MB+, and MB-). The DMC-42x0 decodes either type into
quadrature states or four times the number of cycles. Encoders may also have a third channel (or index) for
synchronization.
The DMC-42x0 can be ordered with 120 Ω termination resistors installed on the encoder inputs. See the Ordering
Options in the Appendix for more information.
The DMC-42x0 can also interface to encoders with pulse and direction signals. Refer to the “CE” command in the
command reference for details.
There is no limit on encoder line density; however, the input frequency to the controller must not exceed 5,500,000
full encoder cycles/second (22,000,000 quadrature counts/sec). For example, if the encoder line density is 10,000
cycles per inch, the maximum speed is 300 inches/second. If higher encoder frequency is required, please consult
the factory.
The standard encoder voltage level is TTL (0-5v), however, voltage levels up to 12 Volts are acceptable. (If using
differential signals, 12 Volts can be input directly to the DMC-42x0. Single-ended 12 Volt signals require a bias
voltage input to the complementary inputs).
The DMC-42x0 can accept analog feedback (±10v) instead of an encoder for any axis. For more information see the
command AF in the command reference.
To interface with other types of position sensors such as absolute encoders, Galil can customize the controller and
command set. Please contact Galil to talk to one of our applications engineers about your particular system
requirements.
Watch Dog Timer
The DMC-42x0 provides an internal watch dog timer which checks for proper microprocessor operation. The timer
toggles the Amplifier Enable Output (AMPEN) which can be used to switch the amplifiers off in the event of a
serious DMC-42x0 failure. The AMPEN output is normally high. During power-up and if the microprocessor ceases
to function properly, the AMPEN output will go low. The error light will also turn on at this stage. A reset is
required to restore the DMC-42x0 to normal operation. Consult the factory for a Return Materials Authorization
(RMA) Number if your DMC-42x0 is damaged.
Chapter 1 Overview ▫ 7 DMC-42x0 User Manual