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26 • Chapter 2 Getting Started DMC-1700/1800
For stepper motor operation, an encoder is optional.
For servo motor operation, if you have a preferred definition of the forward and reverse
directions, make sure that the encoder wiring is consistent with that definition.
The DMC-1700/1800 accepts single-ended or differential encoder feedback with or without
an index pulse. If you are not using the AMP-19x0 or the ICM-1900 you will need to
consult the appendix for the encoder pinouts for connection to the motion controller. The
AMP-19x0 and the ICM-1900 can accept encoder feedback from a 10-pin ribbon cable or
individual signal leads. For a 10-pin ribbon cable encoder, connect the cable to the
protected header connector labeled X ENCODER (repeat for each axis necessary). For
individual wires, simply match the leads from the encoder you are using to the encoder
feedback inputs on the interconnect board. The signal leads are labeled CHA (channel
A), CHB (channel B), and INDEX. For differential encoders, the complement signals are
labeled CHA-, CHB-, and INDEX-.
Note: When using pulse and direction encoders, the pulse signal is connected to CHA and the
direction signal is connected to CHB. The controller must be configured for pulse and
direction with the command CE. See the command summary for further information on
the command CE.
Step D. Verify proper encoder operation.
Start with the X encoder first. Once it is connected, turn the motor shaft and interrogate the
position with the instruction TPX <return>. The controller response will vary as the
motor is turned.
At this point, if TPX does not vary with encoder rotation, there are three possibilities:
1. The encoder connections are incorrect - check the wiring as necessary.
2. The encoder has failed - using an oscilloscope, observe the encoder signals. Verify
that both channels A and B have a peak magnitude between 5 and 12 volts. Note
that if only one encoder channel fails, the position reporting varies by one count
only. If the encoder failed, replace the encoder. If you cannot observe the encoder
signals, try a different encoder.
3. There is a hardware failure in the controller - connect the same encoder to a different
axis. If the problem disappears, you probably have a hardware failure. Consult the
factory for help.
Step E. Connect Hall Sensors if available.
Hall sensors are only used with sinusoidal commutation and are not necessary for proper
operation. The use of hall sensors allows the controller to automatically estimate the
commutation phase upon reset and also provides the controller the ability to set a more
precise commutation phase. Without hall sensors, the commutation phase must be
determined manually.
The hall effect sensors are connected to the digital inputs of the controller. These inputs can
be used with the general use inputs (bits 1-8), the auxiliary encoder inputs (bits 81-96), or
the extended I/O inputs of the DMC-17x8 controller (bits 17-80). Note: The general use
inputs are optoisolated and require a voltage connection at the INCOM point - for more
information regarding the digital inputs, see Chapter 3, Connecting Hardware.
Each set of sensors must use inputs that are in consecutive order. The input lines are specified
with the command, BI. For example, if the Hall sensors of the Z axis are connected to
inputs 6, 7 and 8, use the instruction:
BI ,, 6
or
BIZ = 6