Encoder; Watch Dog Timer - Galil Motion Control DMC-1600 Series User Manual

Encoder

An encoder translates motion into electrical pulses which are fed back into the controller. The
DMC-1600 accepts feedback from either a rotary or linear encoder. Typical encoders provide two
channels in quadrature, known as CHA and CHB. This type of encoder is known as a quadrature
encoder. Quadrature encoders may be either single-ended (CHA and CHB) or differential
(CHA,CHA-,CHB,CHB-). The DMC-1600 decodes either type into quadrature states or four times
the number of cycles. Encoders may also have a third channel (or index) for synchronization.
For stepper motors, the DMC-1600 can also interface to encoders with pulse and direction signals.
There is no limit on encoder line density, however, the input frequency to the controller must not
exceed 3,000,000 full encoder cycles/second (12,000,000 quadrature counts/sec). For example, if
the encoder line density is 10000 cycles per inch, the maximum speed is 300 inches/second. If
higher encoder frequency is required, please consult the factory.
The standard voltage level is TTL (zero to five volts), however, voltage levels up to 12 Volts are
acceptable. (If using differential signals, 12 Volts can be input directly to the DMC-1600. Single-
ended 12 Volt signals require a bias voltage input to the complementary inputs).
The DMC-1600 can accept analog feedback instead of an encoder for any axis. For more
information see description of analog feedback in Chapter 2 under section entitled "Test the
encoder operation".
To interface with other types of position sensors such as resolvers or 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-1600 provides an internal watch dog timer which checks for proper microprocessor
operation. The timer toggles the Amplifier Enable Output (AEN) which can be used to switch the
amplifiers off in the event of a serious DMC-1600 failure. The AEN output is normally high.
During power-up and if the microprocessor ceases to function properly, the AEN output will go
low. The error light for each axis will also turn on at this stage. A reset is required to restore the
DMC-1600 to normal operation. Consult the factory for a Return Materials Authorization (RMA)
Number if your DMC-1600 is damaged.
Chapter 1 Overview • 5
DMC-1600